--- /dev/null
+/*
+ * kernel/lockdep.c
+ *
+ * Runtime locking correctness validator
+ *
+ * Started by Ingo Molnar:
+ *
+ * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * this code maps all the lock dependencies as they occur in a live kernel
+ * and will warn about the following classes of locking bugs:
+ *
+ * - lock inversion scenarios
+ * - circular lock dependencies
+ * - hardirq/softirq safe/unsafe locking bugs
+ *
+ * Bugs are reported even if the current locking scenario does not cause
+ * any deadlock at this point.
+ *
+ * I.e. if anytime in the past two locks were taken in a different order,
+ * even if it happened for another task, even if those were different
+ * locks (but of the same class as this lock), this code will detect it.
+ *
+ * Thanks to Arjan van de Ven for coming up with the initial idea of
+ * mapping lock dependencies runtime.
+ */
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+#include <linux/stacktrace.h>
+#include <linux/debug_locks.h>
+#include <linux/irqflags.h>
+#include <linux/utsname.h>
+
+#include <asm/sections.h>
+
+#include "lockdep_internals.h"
+
+/*
+ * hash_lock: protects the lockdep hashes and class/list/hash allocators.
+ *
+ * This is one of the rare exceptions where it's justified
+ * to use a raw spinlock - we really dont want the spinlock
+ * code to recurse back into the lockdep code.
+ */
+static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+static int lockdep_initialized;
+
+unsigned long nr_list_entries;
+static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
+
+/*
+ * Allocate a lockdep entry. (assumes hash_lock held, returns
+ * with NULL on failure)
+ */
+static struct lock_list *alloc_list_entry(void)
+{
+ if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ return NULL;
+ }
+ return list_entries + nr_list_entries++;
+}
+
+/*
+ * All data structures here are protected by the global debug_lock.
+ *
+ * Mutex key structs only get allocated, once during bootup, and never
+ * get freed - this significantly simplifies the debugging code.
+ */
+unsigned long nr_lock_classes;
+static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
+
+/*
+ * We keep a global list of all lock classes. The list only grows,
+ * never shrinks. The list is only accessed with the lockdep
+ * spinlock lock held.
+ */
+LIST_HEAD(all_lock_classes);
+
+/*
+ * The lockdep classes are in a hash-table as well, for fast lookup:
+ */
+#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
+#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
+#define CLASSHASH_MASK (CLASSHASH_SIZE - 1)
+#define __classhashfn(key) ((((unsigned long)key >> CLASSHASH_BITS) + (unsigned long)key) & CLASSHASH_MASK)
+#define classhashentry(key) (classhash_table + __classhashfn((key)))
+
+static struct list_head classhash_table[CLASSHASH_SIZE];
+
+unsigned long nr_lock_chains;
+static struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
+
+/*
+ * We put the lock dependency chains into a hash-table as well, to cache
+ * their existence:
+ */
+#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
+#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
+#define CHAINHASH_MASK (CHAINHASH_SIZE - 1)
+#define __chainhashfn(chain) \
+ (((chain >> CHAINHASH_BITS) + chain) & CHAINHASH_MASK)
+#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
+
+static struct list_head chainhash_table[CHAINHASH_SIZE];
+
+/*
+ * The hash key of the lock dependency chains is a hash itself too:
+ * it's a hash of all locks taken up to that lock, including that lock.
+ * It's a 64-bit hash, because it's important for the keys to be
+ * unique.
+ */
+#define iterate_chain_key(key1, key2) \
+ (((key1) << MAX_LOCKDEP_KEYS_BITS/2) ^ \
+ ((key1) >> (64-MAX_LOCKDEP_KEYS_BITS/2)) ^ \
+ (key2))
+
+void lockdep_off(void)
+{
+ current->lockdep_recursion++;
+}
+
+EXPORT_SYMBOL(lockdep_off);
+
+void lockdep_on(void)
+{
+ current->lockdep_recursion--;
+}
+
+EXPORT_SYMBOL(lockdep_on);
+
+int lockdep_internal(void)
+{
+ return current->lockdep_recursion != 0;
+}
+
+EXPORT_SYMBOL(lockdep_internal);
+
+/*
+ * Debugging switches:
+ */
+
+#define VERBOSE 0
+#ifdef VERBOSE
+# define VERY_VERBOSE 0
+#endif
+
+#if VERBOSE
+# define HARDIRQ_VERBOSE 1
+# define SOFTIRQ_VERBOSE 1
+#else
+# define HARDIRQ_VERBOSE 0
+# define SOFTIRQ_VERBOSE 0
+#endif
+
+#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
+/*
+ * Quick filtering for interesting events:
+ */
+static int class_filter(struct lock_class *class)
+{
+#if 0
+ /* Example */
+ if (class->name_version == 1 &&
+ !strcmp(class->name, "lockname"))
+ return 1;
+ if (class->name_version == 1 &&
+ !strcmp(class->name, "&struct->lockfield"))
+ return 1;
+#endif
+ /* Allow everything else. 0 would be filter everything else */
+ return 1;
+}
+#endif
+
+static int verbose(struct lock_class *class)
+{
+#if VERBOSE
+ return class_filter(class);
+#endif
+ return 0;
+}
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+static int hardirq_verbose(struct lock_class *class)
+{
+#if HARDIRQ_VERBOSE
+ return class_filter(class);
+#endif
+ return 0;
+}
+
+static int softirq_verbose(struct lock_class *class)
+{
+#if SOFTIRQ_VERBOSE
+ return class_filter(class);
+#endif
+ return 0;
+}
+
+#endif
+
+/*
+ * Stack-trace: tightly packed array of stack backtrace
+ * addresses. Protected by the hash_lock.
+ */
+unsigned long nr_stack_trace_entries;
+static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
+
+static int save_trace(struct stack_trace *trace)
+{
+ trace->nr_entries = 0;
+ trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
+ trace->entries = stack_trace + nr_stack_trace_entries;
+
+ trace->skip = 3;
+ trace->all_contexts = 0;
+
+ /* Make sure to not recurse in case the the unwinder needs to tak
+e locks. */
+ lockdep_off();
+ save_stack_trace(trace, NULL);
+ lockdep_on();
+
+ trace->max_entries = trace->nr_entries;
+
+ nr_stack_trace_entries += trace->nr_entries;
+ if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES))
+ return 0;
+
+ if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
+ __raw_spin_unlock(&hash_lock);
+ if (debug_locks_off()) {
+ printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ dump_stack();
+ }
+ return 0;
+ }
+
+ return 1;
+}
+
+unsigned int nr_hardirq_chains;
+unsigned int nr_softirq_chains;
+unsigned int nr_process_chains;
+unsigned int max_lockdep_depth;
+unsigned int max_recursion_depth;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+/*
+ * We cannot printk in early bootup code. Not even early_printk()
+ * might work. So we mark any initialization errors and printk
+ * about it later on, in lockdep_info().
+ */
+static int lockdep_init_error;
+
+/*
+ * Various lockdep statistics:
+ */
+atomic_t chain_lookup_hits;
+atomic_t chain_lookup_misses;
+atomic_t hardirqs_on_events;
+atomic_t hardirqs_off_events;
+atomic_t redundant_hardirqs_on;
+atomic_t redundant_hardirqs_off;
+atomic_t softirqs_on_events;
+atomic_t softirqs_off_events;
+atomic_t redundant_softirqs_on;
+atomic_t redundant_softirqs_off;
+atomic_t nr_unused_locks;
+atomic_t nr_cyclic_checks;
+atomic_t nr_cyclic_check_recursions;
+atomic_t nr_find_usage_forwards_checks;
+atomic_t nr_find_usage_forwards_recursions;
+atomic_t nr_find_usage_backwards_checks;
+atomic_t nr_find_usage_backwards_recursions;
+# define debug_atomic_inc(ptr) atomic_inc(ptr)
+# define debug_atomic_dec(ptr) atomic_dec(ptr)
+# define debug_atomic_read(ptr) atomic_read(ptr)
+#else
+# define debug_atomic_inc(ptr) do { } while (0)
+# define debug_atomic_dec(ptr) do { } while (0)
+# define debug_atomic_read(ptr) 0
+#endif
+
+/*
+ * Locking printouts:
+ */
+
+static const char *usage_str[] =
+{
+ [LOCK_USED] = "initial-use ",
+ [LOCK_USED_IN_HARDIRQ] = "in-hardirq-W",
+ [LOCK_USED_IN_SOFTIRQ] = "in-softirq-W",
+ [LOCK_ENABLED_SOFTIRQS] = "softirq-on-W",
+ [LOCK_ENABLED_HARDIRQS] = "hardirq-on-W",
+ [LOCK_USED_IN_HARDIRQ_READ] = "in-hardirq-R",
+ [LOCK_USED_IN_SOFTIRQ_READ] = "in-softirq-R",
+ [LOCK_ENABLED_SOFTIRQS_READ] = "softirq-on-R",
+ [LOCK_ENABLED_HARDIRQS_READ] = "hardirq-on-R",
+};
+
+const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
+{
+ unsigned long offs, size;
+ char *modname;
+
+ return kallsyms_lookup((unsigned long)key, &size, &offs, &modname, str);
+}
+
+void
+get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4)
+{
+ *c1 = '.', *c2 = '.', *c3 = '.', *c4 = '.';
+
+ if (class->usage_mask & LOCKF_USED_IN_HARDIRQ)
+ *c1 = '+';
+ else
+ if (class->usage_mask & LOCKF_ENABLED_HARDIRQS)
+ *c1 = '-';
+
+ if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ)
+ *c2 = '+';
+ else
+ if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS)
+ *c2 = '-';
+
+ if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
+ *c3 = '-';
+ if (class->usage_mask & LOCKF_USED_IN_HARDIRQ_READ) {
+ *c3 = '+';
+ if (class->usage_mask & LOCKF_ENABLED_HARDIRQS_READ)
+ *c3 = '?';
+ }
+
+ if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
+ *c4 = '-';
+ if (class->usage_mask & LOCKF_USED_IN_SOFTIRQ_READ) {
+ *c4 = '+';
+ if (class->usage_mask & LOCKF_ENABLED_SOFTIRQS_READ)
+ *c4 = '?';
+ }
+}
+
+static void print_lock_name(struct lock_class *class)
+{
+ char str[128], c1, c2, c3, c4;
+ const char *name;
+
+ get_usage_chars(class, &c1, &c2, &c3, &c4);
+
+ name = class->name;
+ if (!name) {
+ name = __get_key_name(class->key, str);
+ printk(" (%s", name);
+ } else {
+ printk(" (%s", name);
+ if (class->name_version > 1)
+ printk("#%d", class->name_version);
+ if (class->subclass)
+ printk("/%d", class->subclass);
+ }
+ printk("){%c%c%c%c}", c1, c2, c3, c4);
+}
+
+static void print_lockdep_cache(struct lockdep_map *lock)
+{
+ const char *name;
+ char str[128];
+
+ name = lock->name;
+ if (!name)
+ name = __get_key_name(lock->key->subkeys, str);
+
+ printk("%s", name);
+}
+
+static void print_lock(struct held_lock *hlock)
+{
+ print_lock_name(hlock->class);
+ printk(", at: ");
+ print_ip_sym(hlock->acquire_ip);
+}
+
+static void lockdep_print_held_locks(struct task_struct *curr)
+{
+ int i, depth = curr->lockdep_depth;
+
+ if (!depth) {
+ printk("no locks held by %s/%d.\n", curr->comm, curr->pid);
+ return;
+ }
+ printk("%d lock%s held by %s/%d:\n",
+ depth, depth > 1 ? "s" : "", curr->comm, curr->pid);
+
+ for (i = 0; i < depth; i++) {
+ printk(" #%d: ", i);
+ print_lock(curr->held_locks + i);
+ }
+}
+
+static void print_lock_class_header(struct lock_class *class, int depth)
+{
+ int bit;
+
+ printk("%*s->", depth, "");
+ print_lock_name(class);
+ printk(" ops: %lu", class->ops);
+ printk(" {\n");
+
+ for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
+ if (class->usage_mask & (1 << bit)) {
+ int len = depth;
+
+ len += printk("%*s %s", depth, "", usage_str[bit]);
+ len += printk(" at:\n");
+ print_stack_trace(class->usage_traces + bit, len);
+ }
+ }
+ printk("%*s }\n", depth, "");
+
+ printk("%*s ... key at: ",depth,"");
+ print_ip_sym((unsigned long)class->key);
+}
+
+/*
+ * printk all lock dependencies starting at <entry>:
+ */
+static void print_lock_dependencies(struct lock_class *class, int depth)
+{
+ struct lock_list *entry;
+
+ if (DEBUG_LOCKS_WARN_ON(depth >= 20))
+ return;
+
+ print_lock_class_header(class, depth);
+
+ list_for_each_entry(entry, &class->locks_after, entry) {
+ DEBUG_LOCKS_WARN_ON(!entry->class);
+ print_lock_dependencies(entry->class, depth + 1);
+
+ printk("%*s ... acquired at:\n",depth,"");
+ print_stack_trace(&entry->trace, 2);
+ printk("\n");
+ }
+}
+
+/*
+ * Add a new dependency to the head of the list:
+ */
+static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
+ struct list_head *head, unsigned long ip)
+{
+ struct lock_list *entry;
+ /*
+ * Lock not present yet - get a new dependency struct and
+ * add it to the list:
+ */
+ entry = alloc_list_entry();
+ if (!entry)
+ return 0;
+
+ entry->class = this;
+ save_trace(&entry->trace);
+
+ /*
+ * Since we never remove from the dependency list, the list can
+ * be walked lockless by other CPUs, it's only allocation
+ * that must be protected by the spinlock. But this also means
+ * we must make new entries visible only once writes to the
+ * entry become visible - hence the RCU op:
+ */
+ list_add_tail_rcu(&entry->entry, head);
+
+ return 1;
+}
+
+/*
+ * Recursive, forwards-direction lock-dependency checking, used for
+ * both noncyclic checking and for hardirq-unsafe/softirq-unsafe
+ * checking.
+ *
+ * (to keep the stackframe of the recursive functions small we
+ * use these global variables, and we also mark various helper
+ * functions as noinline.)
+ */
+static struct held_lock *check_source, *check_target;
+
+/*
+ * Print a dependency chain entry (this is only done when a deadlock
+ * has been detected):
+ */
+static noinline int
+print_circular_bug_entry(struct lock_list *target, unsigned int depth)
+{
+ if (debug_locks_silent)
+ return 0;
+ printk("\n-> #%u", depth);
+ print_lock_name(target->class);
+ printk(":\n");
+ print_stack_trace(&target->trace, 6);
+
+ return 0;
+}
+
+static void print_kernel_version(void)
+{
+ printk("%s %.*s\n", system_utsname.release,
+ (int)strcspn(system_utsname.version, " "),
+ system_utsname.version);
+}
+
+/*
+ * When a circular dependency is detected, print the
+ * header first:
+ */
+static noinline int
+print_circular_bug_header(struct lock_list *entry, unsigned int depth)
+{
+ struct task_struct *curr = current;
+
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ if (debug_locks_silent)
+ return 0;
+
+ printk("\n=======================================================\n");
+ printk( "[ INFO: possible circular locking dependency detected ]\n");
+ print_kernel_version();
+ printk( "-------------------------------------------------------\n");
+ printk("%s/%d is trying to acquire lock:\n",
+ curr->comm, curr->pid);
+ print_lock(check_source);
+ printk("\nbut task is already holding lock:\n");
+ print_lock(check_target);
+ printk("\nwhich lock already depends on the new lock.\n\n");
+ printk("\nthe existing dependency chain (in reverse order) is:\n");
+
+ print_circular_bug_entry(entry, depth);
+
+ return 0;
+}
+
+static noinline int print_circular_bug_tail(void)
+{
+ struct task_struct *curr = current;
+ struct lock_list this;
+
+ if (debug_locks_silent)
+ return 0;
+
+ this.class = check_source->class;
+ save_trace(&this.trace);
+ print_circular_bug_entry(&this, 0);
+
+ printk("\nother info that might help us debug this:\n\n");
+ lockdep_print_held_locks(curr);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+
+ return 0;
+}
+
+static int noinline print_infinite_recursion_bug(void)
+{
+ __raw_spin_unlock(&hash_lock);
+ DEBUG_LOCKS_WARN_ON(1);
+
+ return 0;
+}
+
+/*
+ * Prove that the dependency graph starting at <entry> can not
+ * lead to <target>. Print an error and return 0 if it does.
+ */
+static noinline int
+check_noncircular(struct lock_class *source, unsigned int depth)
+{
+ struct lock_list *entry;
+
+ debug_atomic_inc(&nr_cyclic_check_recursions);
+ if (depth > max_recursion_depth)
+ max_recursion_depth = depth;
+ if (depth >= 20)
+ return print_infinite_recursion_bug();
+ /*
+ * Check this lock's dependency list:
+ */
+ list_for_each_entry(entry, &source->locks_after, entry) {
+ if (entry->class == check_target->class)
+ return print_circular_bug_header(entry, depth+1);
+ debug_atomic_inc(&nr_cyclic_checks);
+ if (!check_noncircular(entry->class, depth+1))
+ return print_circular_bug_entry(entry, depth+1);
+ }
+ return 1;
+}
+
+static int very_verbose(struct lock_class *class)
+{
+#if VERY_VERBOSE
+ return class_filter(class);
+#endif
+ return 0;
+}
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+/*
+ * Forwards and backwards subgraph searching, for the purposes of
+ * proving that two subgraphs can be connected by a new dependency
+ * without creating any illegal irq-safe -> irq-unsafe lock dependency.
+ */
+static enum lock_usage_bit find_usage_bit;
+static struct lock_class *forwards_match, *backwards_match;
+
+/*
+ * Find a node in the forwards-direction dependency sub-graph starting
+ * at <source> that matches <find_usage_bit>.
+ *
+ * Return 2 if such a node exists in the subgraph, and put that node
+ * into <forwards_match>.
+ *
+ * Return 1 otherwise and keep <forwards_match> unchanged.
+ * Return 0 on error.
+ */
+static noinline int
+find_usage_forwards(struct lock_class *source, unsigned int depth)
+{
+ struct lock_list *entry;
+ int ret;
+
+ if (depth > max_recursion_depth)
+ max_recursion_depth = depth;
+ if (depth >= 20)
+ return print_infinite_recursion_bug();
+
+ debug_atomic_inc(&nr_find_usage_forwards_checks);
+ if (source->usage_mask & (1 << find_usage_bit)) {
+ forwards_match = source;
+ return 2;
+ }
+
+ /*
+ * Check this lock's dependency list:
+ */
+ list_for_each_entry(entry, &source->locks_after, entry) {
+ debug_atomic_inc(&nr_find_usage_forwards_recursions);
+ ret = find_usage_forwards(entry->class, depth+1);
+ if (ret == 2 || ret == 0)
+ return ret;
+ }
+ return 1;
+}
+
+/*
+ * Find a node in the backwards-direction dependency sub-graph starting
+ * at <source> that matches <find_usage_bit>.
+ *
+ * Return 2 if such a node exists in the subgraph, and put that node
+ * into <backwards_match>.
+ *
+ * Return 1 otherwise and keep <backwards_match> unchanged.
+ * Return 0 on error.
+ */
+static noinline int
+find_usage_backwards(struct lock_class *source, unsigned int depth)
+{
+ struct lock_list *entry;
+ int ret;
+
+ if (depth > max_recursion_depth)
+ max_recursion_depth = depth;
+ if (depth >= 20)
+ return print_infinite_recursion_bug();
+
+ debug_atomic_inc(&nr_find_usage_backwards_checks);
+ if (source->usage_mask & (1 << find_usage_bit)) {
+ backwards_match = source;
+ return 2;
+ }
+
+ /*
+ * Check this lock's dependency list:
+ */
+ list_for_each_entry(entry, &source->locks_before, entry) {
+ debug_atomic_inc(&nr_find_usage_backwards_recursions);
+ ret = find_usage_backwards(entry->class, depth+1);
+ if (ret == 2 || ret == 0)
+ return ret;
+ }
+ return 1;
+}
+
+static int
+print_bad_irq_dependency(struct task_struct *curr,
+ struct held_lock *prev,
+ struct held_lock *next,
+ enum lock_usage_bit bit1,
+ enum lock_usage_bit bit2,
+ const char *irqclass)
+{
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ if (debug_locks_silent)
+ return 0;
+
+ printk("\n======================================================\n");
+ printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
+ irqclass, irqclass);
+ print_kernel_version();
+ printk( "------------------------------------------------------\n");
+ printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
+ curr->comm, curr->pid,
+ curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
+ curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
+ curr->hardirqs_enabled,
+ curr->softirqs_enabled);
+ print_lock(next);
+
+ printk("\nand this task is already holding:\n");
+ print_lock(prev);
+ printk("which would create a new lock dependency:\n");
+ print_lock_name(prev->class);
+ printk(" ->");
+ print_lock_name(next->class);
+ printk("\n");
+
+ printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
+ irqclass);
+ print_lock_name(backwards_match);
+ printk("\n... which became %s-irq-safe at:\n", irqclass);
+
+ print_stack_trace(backwards_match->usage_traces + bit1, 1);
+
+ printk("\nto a %s-irq-unsafe lock:\n", irqclass);
+ print_lock_name(forwards_match);
+ printk("\n... which became %s-irq-unsafe at:\n", irqclass);
+ printk("...");
+
+ print_stack_trace(forwards_match->usage_traces + bit2, 1);
+
+ printk("\nother info that might help us debug this:\n\n");
+ lockdep_print_held_locks(curr);
+
+ printk("\nthe %s-irq-safe lock's dependencies:\n", irqclass);
+ print_lock_dependencies(backwards_match, 0);
+
+ printk("\nthe %s-irq-unsafe lock's dependencies:\n", irqclass);
+ print_lock_dependencies(forwards_match, 0);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+
+ return 0;
+}
+
+static int
+check_usage(struct task_struct *curr, struct held_lock *prev,
+ struct held_lock *next, enum lock_usage_bit bit_backwards,
+ enum lock_usage_bit bit_forwards, const char *irqclass)
+{
+ int ret;
+
+ find_usage_bit = bit_backwards;
+ /* fills in <backwards_match> */
+ ret = find_usage_backwards(prev->class, 0);
+ if (!ret || ret == 1)
+ return ret;
+
+ find_usage_bit = bit_forwards;
+ ret = find_usage_forwards(next->class, 0);
+ if (!ret || ret == 1)
+ return ret;
+ /* ret == 2 */
+ return print_bad_irq_dependency(curr, prev, next,
+ bit_backwards, bit_forwards, irqclass);
+}
+
+#endif
+
+static int
+print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
+ struct held_lock *next)
+{
+ debug_locks_off();
+ __raw_spin_unlock(&hash_lock);
+ if (debug_locks_silent)
+ return 0;
+
+ printk("\n=============================================\n");
+ printk( "[ INFO: possible recursive locking detected ]\n");
+ print_kernel_version();
+ printk( "---------------------------------------------\n");
+ printk("%s/%d is trying to acquire lock:\n",
+ curr->comm, curr->pid);
+ print_lock(next);
+ printk("\nbut task is already holding lock:\n");
+ print_lock(prev);
+
+ printk("\nother info that might help us debug this:\n");
+ lockdep_print_held_locks(curr);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+
+ return 0;
+}
+
+/*
+ * Check whether we are holding such a class already.
+ *
+ * (Note that this has to be done separately, because the graph cannot
+ * detect such classes of deadlocks.)
+ *
+ * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
+ */
+static int
+check_deadlock(struct task_struct *curr, struct held_lock *next,
+ struct lockdep_map *next_instance, int read)
+{
+ struct held_lock *prev;
+ int i;
+
+ for (i = 0; i < curr->lockdep_depth; i++) {
+ prev = curr->held_locks + i;
+ if (prev->class != next->class)
+ continue;
+ /*
+ * Allow read-after-read recursion of the same
+ * lock class (i.e. read_lock(lock)+read_lock(lock)):
+ */
+ if ((read == 2) && prev->read)
+ return 2;
+ return print_deadlock_bug(curr, prev, next);
+ }
+ return 1;
+}
+
+/*
+ * There was a chain-cache miss, and we are about to add a new dependency
+ * to a previous lock. We recursively validate the following rules:
+ *
+ * - would the adding of the <prev> -> <next> dependency create a
+ * circular dependency in the graph? [== circular deadlock]
+ *
+ * - does the new prev->next dependency connect any hardirq-safe lock
+ * (in the full backwards-subgraph starting at <prev>) with any
+ * hardirq-unsafe lock (in the full forwards-subgraph starting at
+ * <next>)? [== illegal lock inversion with hardirq contexts]
+ *
+ * - does the new prev->next dependency connect any softirq-safe lock
+ * (in the full backwards-subgraph starting at <prev>) with any
+ * softirq-unsafe lock (in the full forwards-subgraph starting at
+ * <next>)? [== illegal lock inversion with softirq contexts]
+ *
+ * any of these scenarios could lead to a deadlock.
+ *
+ * Then if all the validations pass, we add the forwards and backwards
+ * dependency.
+ */
+static int
+check_prev_add(struct task_struct *curr, struct held_lock *prev,
+ struct held_lock *next)
+{
+ struct lock_list *entry;
+ int ret;
+
+ /*
+ * Prove that the new <prev> -> <next> dependency would not
+ * create a circular dependency in the graph. (We do this by
+ * forward-recursing into the graph starting at <next>, and
+ * checking whether we can reach <prev>.)
+ *
+ * We are using global variables to control the recursion, to
+ * keep the stackframe size of the recursive functions low:
+ */
+ check_source = next;
+ check_target = prev;
+ if (!(check_noncircular(next->class, 0)))
+ return print_circular_bug_tail();
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ /*
+ * Prove that the new dependency does not connect a hardirq-safe
+ * lock with a hardirq-unsafe lock - to achieve this we search
+ * the backwards-subgraph starting at <prev>, and the
+ * forwards-subgraph starting at <next>:
+ */
+ if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ,
+ LOCK_ENABLED_HARDIRQS, "hard"))
+ return 0;
+
+ /*
+ * Prove that the new dependency does not connect a hardirq-safe-read
+ * lock with a hardirq-unsafe lock - to achieve this we search
+ * the backwards-subgraph starting at <prev>, and the
+ * forwards-subgraph starting at <next>:
+ */
+ if (!check_usage(curr, prev, next, LOCK_USED_IN_HARDIRQ_READ,
+ LOCK_ENABLED_HARDIRQS, "hard-read"))
+ return 0;
+
+ /*
+ * Prove that the new dependency does not connect a softirq-safe
+ * lock with a softirq-unsafe lock - to achieve this we search
+ * the backwards-subgraph starting at <prev>, and the
+ * forwards-subgraph starting at <next>:
+ */
+ if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ,
+ LOCK_ENABLED_SOFTIRQS, "soft"))
+ return 0;
+ /*
+ * Prove that the new dependency does not connect a softirq-safe-read
+ * lock with a softirq-unsafe lock - to achieve this we search
+ * the backwards-subgraph starting at <prev>, and the
+ * forwards-subgraph starting at <next>:
+ */
+ if (!check_usage(curr, prev, next, LOCK_USED_IN_SOFTIRQ_READ,
+ LOCK_ENABLED_SOFTIRQS, "soft"))
+ return 0;
+#endif
+ /*
+ * For recursive read-locks we do all the dependency checks,
+ * but we dont store read-triggered dependencies (only
+ * write-triggered dependencies). This ensures that only the
+ * write-side dependencies matter, and that if for example a
+ * write-lock never takes any other locks, then the reads are
+ * equivalent to a NOP.
+ */
+ if (next->read == 2 || prev->read == 2)
+ return 1;
+ /*
+ * Is the <prev> -> <next> dependency already present?
+ *
+ * (this may occur even though this is a new chain: consider
+ * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
+ * chains - the second one will be new, but L1 already has
+ * L2 added to its dependency list, due to the first chain.)
+ */
+ list_for_each_entry(entry, &prev->class->locks_after, entry) {
+ if (entry->class == next->class)
+ return 2;
+ }
+
+ /*
+ * Ok, all validations passed, add the new lock
+ * to the previous lock's dependency list:
+ */
+ ret = add_lock_to_list(prev->class, next->class,
+ &prev->class->locks_after, next->acquire_ip);
+ if (!ret)
+ return 0;
+ /*
+ * Return value of 2 signals 'dependency already added',
+ * in that case we dont have to add the backlink either.
+ */
+ if (ret == 2)
+ return 2;
+ ret = add_lock_to_list(next->class, prev->class,
+ &next->class->locks_before, next->acquire_ip);
+
+ /*
+ * Debugging printouts:
+ */
+ if (verbose(prev->class) || verbose(next->class)) {
+ __raw_spin_unlock(&hash_lock);
+ printk("\n new dependency: ");
+ print_lock_name(prev->class);
+ printk(" => ");
+ print_lock_name(next->class);
+ printk("\n");
+ dump_stack();
+ __raw_spin_lock(&hash_lock);
+ }
+ return 1;
+}
+
+/*
+ * Add the dependency to all directly-previous locks that are 'relevant'.
+ * The ones that are relevant are (in increasing distance from curr):
+ * all consecutive trylock entries and the final non-trylock entry - or
+ * the end of this context's lock-chain - whichever comes first.
+ */
+static int
+check_prevs_add(struct task_struct *curr, struct held_lock *next)
+{
+ int depth = curr->lockdep_depth;
+ struct held_lock *hlock;
+
+ /*
+ * Debugging checks.
+ *
+ * Depth must not be zero for a non-head lock:
+ */
+ if (!depth)
+ goto out_bug;
+ /*
+ * At least two relevant locks must exist for this
+ * to be a head:
+ */
+ if (curr->held_locks[depth].irq_context !=
+ curr->held_locks[depth-1].irq_context)
+ goto out_bug;
+
+ for (;;) {
+ hlock = curr->held_locks + depth-1;
+ /*
+ * Only non-recursive-read entries get new dependencies
+ * added:
+ */
+ if (hlock->read != 2) {
+ check_prev_add(curr, hlock, next);
+ /*
+ * Stop after the first non-trylock entry,
+ * as non-trylock entries have added their
+ * own direct dependencies already, so this
+ * lock is connected to them indirectly:
+ */
+ if (!hlock->trylock)
+ break;
+ }
+ depth--;
+ /*
+ * End of lock-stack?
+ */
+ if (!depth)
+ break;
+ /*
+ * Stop the search if we cross into another context:
+ */
+ if (curr->held_locks[depth].irq_context !=
+ curr->held_locks[depth-1].irq_context)
+ break;
+ }
+ return 1;
+out_bug:
+ __raw_spin_unlock(&hash_lock);
+ DEBUG_LOCKS_WARN_ON(1);
+
+ return 0;
+}
+
+
+/*
+ * Is this the address of a static object:
+ */
+static int static_obj(void *obj)
+{
+ unsigned long start = (unsigned long) &_stext,
+ end = (unsigned long) &_end,
+ addr = (unsigned long) obj;
+#ifdef CONFIG_SMP
+ int i;
+#endif
+
+ /*
+ * static variable?
+ */
+ if ((addr >= start) && (addr < end))
+ return 1;
+
+#ifdef CONFIG_SMP
+ /*
+ * percpu var?
+ */
+ for_each_possible_cpu(i) {
+ start = (unsigned long) &__per_cpu_start + per_cpu_offset(i);
+ end = (unsigned long) &__per_cpu_end + per_cpu_offset(i);
+
+ if ((addr >= start) && (addr < end))
+ return 1;
+ }
+#endif
+
+ /*
+ * module var?
+ */
+ return is_module_address(addr);
+}
+
+/*
+ * To make lock name printouts unique, we calculate a unique
+ * class->name_version generation counter:
+ */
+static int count_matching_names(struct lock_class *new_class)
+{
+ struct lock_class *class;
+ int count = 0;
+
+ if (!new_class->name)
+ return 0;
+
+ list_for_each_entry(class, &all_lock_classes, lock_entry) {
+ if (new_class->key - new_class->subclass == class->key)
+ return class->name_version;
+ if (class->name && !strcmp(class->name, new_class->name))
+ count = max(count, class->name_version);
+ }
+
+ return count + 1;
+}
+
+extern void __error_too_big_MAX_LOCKDEP_SUBCLASSES(void);
+
+/*
+ * Register a lock's class in the hash-table, if the class is not present
+ * yet. Otherwise we look it up. We cache the result in the lock object
+ * itself, so actual lookup of the hash should be once per lock object.
+ */
+static inline struct lock_class *
+look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
+{
+ struct lockdep_subclass_key *key;
+ struct list_head *hash_head;
+ struct lock_class *class;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+ /*
+ * If the architecture calls into lockdep before initializing
+ * the hashes then we'll warn about it later. (we cannot printk
+ * right now)
+ */
+ if (unlikely(!lockdep_initialized)) {
+ lockdep_init();
+ lockdep_init_error = 1;
+ }
+#endif
+
+ /*
+ * Static locks do not have their class-keys yet - for them the key
+ * is the lock object itself:
+ */
+ if (unlikely(!lock->key))
+ lock->key = (void *)lock;
+
+ /*
+ * NOTE: the class-key must be unique. For dynamic locks, a static
+ * lock_class_key variable is passed in through the mutex_init()
+ * (or spin_lock_init()) call - which acts as the key. For static
+ * locks we use the lock object itself as the key.
+ */
+ if (sizeof(struct lock_class_key) > sizeof(struct lock_class))
+ __error_too_big_MAX_LOCKDEP_SUBCLASSES();
+
+ key = lock->key->subkeys + subclass;
+
+ hash_head = classhashentry(key);
+
+ /*
+ * We can walk the hash lockfree, because the hash only
+ * grows, and we are careful when adding entries to the end:
+ */
+ list_for_each_entry(class, hash_head, hash_entry)
+ if (class->key == key)
+ return class;
+
+ return NULL;
+}
+
+/*
+ * Register a lock's class in the hash-table, if the class is not present
+ * yet. Otherwise we look it up. We cache the result in the lock object
+ * itself, so actual lookup of the hash should be once per lock object.
+ */
+static inline struct lock_class *
+register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
+{
+ struct lockdep_subclass_key *key;
+ struct list_head *hash_head;
+ struct lock_class *class;
+
+ class = look_up_lock_class(lock, subclass);
+ if (likely(class))
+ return class;
+
+ /*
+ * Debug-check: all keys must be persistent!
+ */
+ if (!static_obj(lock->key)) {
+ debug_locks_off();
+ printk("INFO: trying to register non-static key.\n");
+ printk("the code is fine but needs lockdep annotation.\n");
+ printk("turning off the locking correctness validator.\n");
+ dump_stack();
+
+ return NULL;
+ }
+
+ key = lock->key->subkeys + subclass;
+ hash_head = classhashentry(key);
+
+ __raw_spin_lock(&hash_lock);
+ /*
+ * We have to do the hash-walk again, to avoid races
+ * with another CPU:
+ */
+ list_for_each_entry(class, hash_head, hash_entry)
+ if (class->key == key)
+ goto out_unlock_set;
+ /*
+ * Allocate a new key from the static array, and add it to
+ * the hash:
+ */
+ if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ return NULL;
+ }
+ class = lock_classes + nr_lock_classes++;
+ debug_atomic_inc(&nr_unused_locks);
+ class->key = key;
+ class->name = lock->name;
+ class->subclass = subclass;
+ INIT_LIST_HEAD(&class->lock_entry);
+ INIT_LIST_HEAD(&class->locks_before);
+ INIT_LIST_HEAD(&class->locks_after);
+ class->name_version = count_matching_names(class);
+ /*
+ * We use RCU's safe list-add method to make
+ * parallel walking of the hash-list safe:
+ */
+ list_add_tail_rcu(&class->hash_entry, hash_head);
+
+ if (verbose(class)) {
+ __raw_spin_unlock(&hash_lock);
+ printk("\nnew class %p: %s", class->key, class->name);
+ if (class->name_version > 1)
+ printk("#%d", class->name_version);
+ printk("\n");
+ dump_stack();
+ __raw_spin_lock(&hash_lock);
+ }
+out_unlock_set:
+ __raw_spin_unlock(&hash_lock);
+
+ if (!subclass || force)
+ lock->class_cache = class;
+
+ DEBUG_LOCKS_WARN_ON(class->subclass != subclass);
+
+ return class;
+}
+
+/*
+ * Look up a dependency chain. If the key is not present yet then
+ * add it and return 0 - in this case the new dependency chain is
+ * validated. If the key is already hashed, return 1.
+ */
+static inline int lookup_chain_cache(u64 chain_key)
+{
+ struct list_head *hash_head = chainhashentry(chain_key);
+ struct lock_chain *chain;
+
+ DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+ /*
+ * We can walk it lock-free, because entries only get added
+ * to the hash:
+ */
+ list_for_each_entry(chain, hash_head, entry) {
+ if (chain->chain_key == chain_key) {
+cache_hit:
+ debug_atomic_inc(&chain_lookup_hits);
+ /*
+ * In the debugging case, force redundant checking
+ * by returning 1:
+ */
+#ifdef CONFIG_DEBUG_LOCKDEP
+ __raw_spin_lock(&hash_lock);
+ return 1;
+#endif
+ return 0;
+ }
+ }
+ /*
+ * Allocate a new chain entry from the static array, and add
+ * it to the hash:
+ */
+ __raw_spin_lock(&hash_lock);
+ /*
+ * We have to walk the chain again locked - to avoid duplicates:
+ */
+ list_for_each_entry(chain, hash_head, entry) {
+ if (chain->chain_key == chain_key) {
+ __raw_spin_unlock(&hash_lock);
+ goto cache_hit;
+ }
+ }
+ if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ return 0;
+ }
+ chain = lock_chains + nr_lock_chains++;
+ chain->chain_key = chain_key;
+ list_add_tail_rcu(&chain->entry, hash_head);
+ debug_atomic_inc(&chain_lookup_misses);
+#ifdef CONFIG_TRACE_IRQFLAGS
+ if (current->hardirq_context)
+ nr_hardirq_chains++;
+ else {
+ if (current->softirq_context)
+ nr_softirq_chains++;
+ else
+ nr_process_chains++;
+ }
+#else
+ nr_process_chains++;
+#endif
+
+ return 1;
+}
+
+/*
+ * We are building curr_chain_key incrementally, so double-check
+ * it from scratch, to make sure that it's done correctly:
+ */
+static void check_chain_key(struct task_struct *curr)
+{
+#ifdef CONFIG_DEBUG_LOCKDEP
+ struct held_lock *hlock, *prev_hlock = NULL;
+ unsigned int i, id;
+ u64 chain_key = 0;
+
+ for (i = 0; i < curr->lockdep_depth; i++) {
+ hlock = curr->held_locks + i;
+ if (chain_key != hlock->prev_chain_key) {
+ debug_locks_off();
+ printk("hm#1, depth: %u [%u], %016Lx != %016Lx\n",
+ curr->lockdep_depth, i,
+ (unsigned long long)chain_key,
+ (unsigned long long)hlock->prev_chain_key);
+ WARN_ON(1);
+ return;
+ }
+ id = hlock->class - lock_classes;
+ DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS);
+ if (prev_hlock && (prev_hlock->irq_context !=
+ hlock->irq_context))
+ chain_key = 0;
+ chain_key = iterate_chain_key(chain_key, id);
+ prev_hlock = hlock;
+ }
+ if (chain_key != curr->curr_chain_key) {
+ debug_locks_off();
+ printk("hm#2, depth: %u [%u], %016Lx != %016Lx\n",
+ curr->lockdep_depth, i,
+ (unsigned long long)chain_key,
+ (unsigned long long)curr->curr_chain_key);
+ WARN_ON(1);
+ }
+#endif
+}
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+/*
+ * print irq inversion bug:
+ */
+static int
+print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
+ struct held_lock *this, int forwards,
+ const char *irqclass)
+{
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ if (debug_locks_silent)
+ return 0;
+
+ printk("\n=========================================================\n");
+ printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
+ print_kernel_version();
+ printk( "---------------------------------------------------------\n");
+ printk("%s/%d just changed the state of lock:\n",
+ curr->comm, curr->pid);
+ print_lock(this);
+ if (forwards)
+ printk("but this lock took another, %s-irq-unsafe lock in the past:\n", irqclass);
+ else
+ printk("but this lock was taken by another, %s-irq-safe lock in the past:\n", irqclass);
+ print_lock_name(other);
+ printk("\n\nand interrupts could create inverse lock ordering between them.\n\n");
+
+ printk("\nother info that might help us debug this:\n");
+ lockdep_print_held_locks(curr);
+
+ printk("\nthe first lock's dependencies:\n");
+ print_lock_dependencies(this->class, 0);
+
+ printk("\nthe second lock's dependencies:\n");
+ print_lock_dependencies(other, 0);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+
+ return 0;
+}
+
+/*
+ * Prove that in the forwards-direction subgraph starting at <this>
+ * there is no lock matching <mask>:
+ */
+static int
+check_usage_forwards(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit bit, const char *irqclass)
+{
+ int ret;
+
+ find_usage_bit = bit;
+ /* fills in <forwards_match> */
+ ret = find_usage_forwards(this->class, 0);
+ if (!ret || ret == 1)
+ return ret;
+
+ return print_irq_inversion_bug(curr, forwards_match, this, 1, irqclass);
+}
+
+/*
+ * Prove that in the backwards-direction subgraph starting at <this>
+ * there is no lock matching <mask>:
+ */
+static int
+check_usage_backwards(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit bit, const char *irqclass)
+{
+ int ret;
+
+ find_usage_bit = bit;
+ /* fills in <backwards_match> */
+ ret = find_usage_backwards(this->class, 0);
+ if (!ret || ret == 1)
+ return ret;
+
+ return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
+}
+
+static inline void print_irqtrace_events(struct task_struct *curr)
+{
+ printk("irq event stamp: %u\n", curr->irq_events);
+ printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
+ print_ip_sym(curr->hardirq_enable_ip);
+ printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
+ print_ip_sym(curr->hardirq_disable_ip);
+ printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
+ print_ip_sym(curr->softirq_enable_ip);
+ printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
+ print_ip_sym(curr->softirq_disable_ip);
+}
+
+#else
+static inline void print_irqtrace_events(struct task_struct *curr)
+{
+}
+#endif
+
+static int
+print_usage_bug(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
+{
+ __raw_spin_unlock(&hash_lock);
+ debug_locks_off();
+ if (debug_locks_silent)
+ return 0;
+
+ printk("\n=================================\n");
+ printk( "[ INFO: inconsistent lock state ]\n");
+ print_kernel_version();
+ printk( "---------------------------------\n");
+
+ printk("inconsistent {%s} -> {%s} usage.\n",
+ usage_str[prev_bit], usage_str[new_bit]);
+
+ printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
+ curr->comm, curr->pid,
+ trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
+ trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
+ trace_hardirqs_enabled(curr),
+ trace_softirqs_enabled(curr));
+ print_lock(this);
+
+ printk("{%s} state was registered at:\n", usage_str[prev_bit]);
+ print_stack_trace(this->class->usage_traces + prev_bit, 1);
+
+ print_irqtrace_events(curr);
+ printk("\nother info that might help us debug this:\n");
+ lockdep_print_held_locks(curr);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+
+ return 0;
+}
+
+/*
+ * Print out an error if an invalid bit is set:
+ */
+static inline int
+valid_state(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
+{
+ if (unlikely(this->class->usage_mask & (1 << bad_bit)))
+ return print_usage_bug(curr, this, bad_bit, new_bit);
+ return 1;
+}
+
+#define STRICT_READ_CHECKS 1
+
+/*
+ * Mark a lock with a usage bit, and validate the state transition:
+ */
+static int mark_lock(struct task_struct *curr, struct held_lock *this,
+ enum lock_usage_bit new_bit, unsigned long ip)
+{
+ unsigned int new_mask = 1 << new_bit, ret = 1;
+
+ /*
+ * If already set then do not dirty the cacheline,
+ * nor do any checks:
+ */
+ if (likely(this->class->usage_mask & new_mask))
+ return 1;
+
+ __raw_spin_lock(&hash_lock);
+ /*
+ * Make sure we didnt race:
+ */
+ if (unlikely(this->class->usage_mask & new_mask)) {
+ __raw_spin_unlock(&hash_lock);
+ return 1;
+ }
+
+ this->class->usage_mask |= new_mask;
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ if (new_bit == LOCK_ENABLED_HARDIRQS ||
+ new_bit == LOCK_ENABLED_HARDIRQS_READ)
+ ip = curr->hardirq_enable_ip;
+ else if (new_bit == LOCK_ENABLED_SOFTIRQS ||
+ new_bit == LOCK_ENABLED_SOFTIRQS_READ)
+ ip = curr->softirq_enable_ip;
+#endif
+ if (!save_trace(this->class->usage_traces + new_bit))
+ return 0;
+
+ switch (new_bit) {
+#ifdef CONFIG_TRACE_IRQFLAGS
+ case LOCK_USED_IN_HARDIRQ:
+ if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
+ return 0;
+ if (!valid_state(curr, this, new_bit,
+ LOCK_ENABLED_HARDIRQS_READ))
+ return 0;
+ /*
+ * just marked it hardirq-safe, check that this lock
+ * took no hardirq-unsafe lock in the past:
+ */
+ if (!check_usage_forwards(curr, this,
+ LOCK_ENABLED_HARDIRQS, "hard"))
+ return 0;
+#if STRICT_READ_CHECKS
+ /*
+ * just marked it hardirq-safe, check that this lock
+ * took no hardirq-unsafe-read lock in the past:
+ */
+ if (!check_usage_forwards(curr, this,
+ LOCK_ENABLED_HARDIRQS_READ, "hard-read"))
+ return 0;
+#endif
+ if (hardirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_USED_IN_SOFTIRQ:
+ if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
+ return 0;
+ if (!valid_state(curr, this, new_bit,
+ LOCK_ENABLED_SOFTIRQS_READ))
+ return 0;
+ /*
+ * just marked it softirq-safe, check that this lock
+ * took no softirq-unsafe lock in the past:
+ */
+ if (!check_usage_forwards(curr, this,
+ LOCK_ENABLED_SOFTIRQS, "soft"))
+ return 0;
+#if STRICT_READ_CHECKS
+ /*
+ * just marked it softirq-safe, check that this lock
+ * took no softirq-unsafe-read lock in the past:
+ */
+ if (!check_usage_forwards(curr, this,
+ LOCK_ENABLED_SOFTIRQS_READ, "soft-read"))
+ return 0;
+#endif
+ if (softirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_USED_IN_HARDIRQ_READ:
+ if (!valid_state(curr, this, new_bit, LOCK_ENABLED_HARDIRQS))
+ return 0;
+ /*
+ * just marked it hardirq-read-safe, check that this lock
+ * took no hardirq-unsafe lock in the past:
+ */
+ if (!check_usage_forwards(curr, this,
+ LOCK_ENABLED_HARDIRQS, "hard"))
+ return 0;
+ if (hardirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_USED_IN_SOFTIRQ_READ:
+ if (!valid_state(curr, this, new_bit, LOCK_ENABLED_SOFTIRQS))
+ return 0;
+ /*
+ * just marked it softirq-read-safe, check that this lock
+ * took no softirq-unsafe lock in the past:
+ */
+ if (!check_usage_forwards(curr, this,
+ LOCK_ENABLED_SOFTIRQS, "soft"))
+ return 0;
+ if (softirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_ENABLED_HARDIRQS:
+ if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
+ return 0;
+ if (!valid_state(curr, this, new_bit,
+ LOCK_USED_IN_HARDIRQ_READ))
+ return 0;
+ /*
+ * just marked it hardirq-unsafe, check that no hardirq-safe
+ * lock in the system ever took it in the past:
+ */
+ if (!check_usage_backwards(curr, this,
+ LOCK_USED_IN_HARDIRQ, "hard"))
+ return 0;
+#if STRICT_READ_CHECKS
+ /*
+ * just marked it hardirq-unsafe, check that no
+ * hardirq-safe-read lock in the system ever took
+ * it in the past:
+ */
+ if (!check_usage_backwards(curr, this,
+ LOCK_USED_IN_HARDIRQ_READ, "hard-read"))
+ return 0;
+#endif
+ if (hardirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_ENABLED_SOFTIRQS:
+ if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
+ return 0;
+ if (!valid_state(curr, this, new_bit,
+ LOCK_USED_IN_SOFTIRQ_READ))
+ return 0;
+ /*
+ * just marked it softirq-unsafe, check that no softirq-safe
+ * lock in the system ever took it in the past:
+ */
+ if (!check_usage_backwards(curr, this,
+ LOCK_USED_IN_SOFTIRQ, "soft"))
+ return 0;
+#if STRICT_READ_CHECKS
+ /*
+ * just marked it softirq-unsafe, check that no
+ * softirq-safe-read lock in the system ever took
+ * it in the past:
+ */
+ if (!check_usage_backwards(curr, this,
+ LOCK_USED_IN_SOFTIRQ_READ, "soft-read"))
+ return 0;
+#endif
+ if (softirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_ENABLED_HARDIRQS_READ:
+ if (!valid_state(curr, this, new_bit, LOCK_USED_IN_HARDIRQ))
+ return 0;
+#if STRICT_READ_CHECKS
+ /*
+ * just marked it hardirq-read-unsafe, check that no
+ * hardirq-safe lock in the system ever took it in the past:
+ */
+ if (!check_usage_backwards(curr, this,
+ LOCK_USED_IN_HARDIRQ, "hard"))
+ return 0;
+#endif
+ if (hardirq_verbose(this->class))
+ ret = 2;
+ break;
+ case LOCK_ENABLED_SOFTIRQS_READ:
+ if (!valid_state(curr, this, new_bit, LOCK_USED_IN_SOFTIRQ))
+ return 0;
+#if STRICT_READ_CHECKS
+ /*
+ * just marked it softirq-read-unsafe, check that no
+ * softirq-safe lock in the system ever took it in the past:
+ */
+ if (!check_usage_backwards(curr, this,
+ LOCK_USED_IN_SOFTIRQ, "soft"))
+ return 0;
+#endif
+ if (softirq_verbose(this->class))
+ ret = 2;
+ break;
+#endif
+ case LOCK_USED:
+ /*
+ * Add it to the global list of classes:
+ */
+ list_add_tail_rcu(&this->class->lock_entry, &all_lock_classes);
+ debug_atomic_dec(&nr_unused_locks);
+ break;
+ default:
+ debug_locks_off();
+ WARN_ON(1);
+ return 0;
+ }
+
+ __raw_spin_unlock(&hash_lock);
+
+ /*
+ * We must printk outside of the hash_lock:
+ */
+ if (ret == 2) {
+ printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
+ print_lock(this);
+ print_irqtrace_events(curr);
+ dump_stack();
+ }
+
+ return ret;
+}
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+/*
+ * Mark all held locks with a usage bit:
+ */
+static int
+mark_held_locks(struct task_struct *curr, int hardirq, unsigned long ip)
+{
+ enum lock_usage_bit usage_bit;
+ struct held_lock *hlock;
+ int i;
+
+ for (i = 0; i < curr->lockdep_depth; i++) {
+ hlock = curr->held_locks + i;
+
+ if (hardirq) {
+ if (hlock->read)
+ usage_bit = LOCK_ENABLED_HARDIRQS_READ;
+ else
+ usage_bit = LOCK_ENABLED_HARDIRQS;
+ } else {
+ if (hlock->read)
+ usage_bit = LOCK_ENABLED_SOFTIRQS_READ;
+ else
+ usage_bit = LOCK_ENABLED_SOFTIRQS;
+ }
+ if (!mark_lock(curr, hlock, usage_bit, ip))
+ return 0;
+ }
+
+ return 1;
+}
+
+/*
+ * Debugging helper: via this flag we know that we are in
+ * 'early bootup code', and will warn about any invalid irqs-on event:
+ */
+static int early_boot_irqs_enabled;
+
+void early_boot_irqs_off(void)
+{
+ early_boot_irqs_enabled = 0;
+}
+
+void early_boot_irqs_on(void)
+{
+ early_boot_irqs_enabled = 1;
+}
+
+/*
+ * Hardirqs will be enabled:
+ */
+void trace_hardirqs_on(void)
+{
+ struct task_struct *curr = current;
+ unsigned long ip;
+
+ if (unlikely(!debug_locks || current->lockdep_recursion))
+ return;
+
+ if (DEBUG_LOCKS_WARN_ON(unlikely(!early_boot_irqs_enabled)))
+ return;
+
+ if (unlikely(curr->hardirqs_enabled)) {
+ debug_atomic_inc(&redundant_hardirqs_on);
+ return;
+ }
+ /* we'll do an OFF -> ON transition: */
+ curr->hardirqs_enabled = 1;
+ ip = (unsigned long) __builtin_return_address(0);
+
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return;
+ if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+ return;
+ /*
+ * We are going to turn hardirqs on, so set the
+ * usage bit for all held locks:
+ */
+ if (!mark_held_locks(curr, 1, ip))
+ return;
+ /*
+ * If we have softirqs enabled, then set the usage
+ * bit for all held locks. (disabled hardirqs prevented
+ * this bit from being set before)
+ */
+ if (curr->softirqs_enabled)
+ if (!mark_held_locks(curr, 0, ip))
+ return;
+
+ curr->hardirq_enable_ip = ip;
+ curr->hardirq_enable_event = ++curr->irq_events;
+ debug_atomic_inc(&hardirqs_on_events);
+}
+
+EXPORT_SYMBOL(trace_hardirqs_on);
+
+/*
+ * Hardirqs were disabled:
+ */
+void trace_hardirqs_off(void)
+{
+ struct task_struct *curr = current;
+
+ if (unlikely(!debug_locks || current->lockdep_recursion))
+ return;
+
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return;
+
+ if (curr->hardirqs_enabled) {
+ /*
+ * We have done an ON -> OFF transition:
+ */
+ curr->hardirqs_enabled = 0;
+ curr->hardirq_disable_ip = _RET_IP_;
+ curr->hardirq_disable_event = ++curr->irq_events;
+ debug_atomic_inc(&hardirqs_off_events);
+ } else
+ debug_atomic_inc(&redundant_hardirqs_off);
+}
+
+EXPORT_SYMBOL(trace_hardirqs_off);
+
+/*
+ * Softirqs will be enabled:
+ */
+void trace_softirqs_on(unsigned long ip)
+{
+ struct task_struct *curr = current;
+
+ if (unlikely(!debug_locks))
+ return;
+
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return;
+
+ if (curr->softirqs_enabled) {
+ debug_atomic_inc(&redundant_softirqs_on);
+ return;
+ }
+
+ /*
+ * We'll do an OFF -> ON transition:
+ */
+ curr->softirqs_enabled = 1;
+ curr->softirq_enable_ip = ip;
+ curr->softirq_enable_event = ++curr->irq_events;
+ debug_atomic_inc(&softirqs_on_events);
+ /*
+ * We are going to turn softirqs on, so set the
+ * usage bit for all held locks, if hardirqs are
+ * enabled too:
+ */
+ if (curr->hardirqs_enabled)
+ mark_held_locks(curr, 0, ip);
+}
+
+/*
+ * Softirqs were disabled:
+ */
+void trace_softirqs_off(unsigned long ip)
+{
+ struct task_struct *curr = current;
+
+ if (unlikely(!debug_locks))
+ return;
+
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return;
+
+ if (curr->softirqs_enabled) {
+ /*
+ * We have done an ON -> OFF transition:
+ */
+ curr->softirqs_enabled = 0;
+ curr->softirq_disable_ip = ip;
+ curr->softirq_disable_event = ++curr->irq_events;
+ debug_atomic_inc(&softirqs_off_events);
+ DEBUG_LOCKS_WARN_ON(!softirq_count());
+ } else
+ debug_atomic_inc(&redundant_softirqs_off);
+}
+
+#endif
+
+/*
+ * Initialize a lock instance's lock-class mapping info:
+ */
+void lockdep_init_map(struct lockdep_map *lock, const char *name,
+ struct lock_class_key *key, int subclass)
+{
+ if (unlikely(!debug_locks))
+ return;
+
+ if (DEBUG_LOCKS_WARN_ON(!key))
+ return;
+ if (DEBUG_LOCKS_WARN_ON(!name))
+ return;
+ /*
+ * Sanity check, the lock-class key must be persistent:
+ */
+ if (!static_obj(key)) {
+ printk("BUG: key %p not in .data!\n", key);
+ DEBUG_LOCKS_WARN_ON(1);
+ return;
+ }
+ lock->name = name;
+ lock->key = key;
+ lock->class_cache = NULL;
+ if (subclass)
+ register_lock_class(lock, subclass, 1);
+}
+
+EXPORT_SYMBOL_GPL(lockdep_init_map);
+
+/*
+ * This gets called for every mutex_lock*()/spin_lock*() operation.
+ * We maintain the dependency maps and validate the locking attempt:
+ */
+static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
+ int trylock, int read, int check, int hardirqs_off,
+ unsigned long ip)
+{
+ struct task_struct *curr = current;
+ struct lock_class *class = NULL;
+ struct held_lock *hlock;
+ unsigned int depth, id;
+ int chain_head = 0;
+ u64 chain_key;
+
+ if (unlikely(!debug_locks))
+ return 0;
+
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return 0;
+
+ if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
+ debug_locks_off();
+ printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ return 0;
+ }
+
+ if (!subclass)
+ class = lock->class_cache;
+ /*
+ * Not cached yet or subclass?
+ */
+ if (unlikely(!class)) {
+ class = register_lock_class(lock, subclass, 0);
+ if (!class)
+ return 0;
+ }
+ debug_atomic_inc((atomic_t *)&class->ops);
+ if (very_verbose(class)) {
+ printk("\nacquire class [%p] %s", class->key, class->name);
+ if (class->name_version > 1)
+ printk("#%d", class->name_version);
+ printk("\n");
+ dump_stack();
+ }
+
+ /*
+ * Add the lock to the list of currently held locks.
+ * (we dont increase the depth just yet, up until the
+ * dependency checks are done)
+ */
+ depth = curr->lockdep_depth;
+ if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
+ return 0;
+
+ hlock = curr->held_locks + depth;
+
+ hlock->class = class;
+ hlock->acquire_ip = ip;
+ hlock->instance = lock;
+ hlock->trylock = trylock;
+ hlock->read = read;
+ hlock->check = check;
+ hlock->hardirqs_off = hardirqs_off;
+
+ if (check != 2)
+ goto out_calc_hash;
+#ifdef CONFIG_TRACE_IRQFLAGS
+ /*
+ * If non-trylock use in a hardirq or softirq context, then
+ * mark the lock as used in these contexts:
+ */
+ if (!trylock) {
+ if (read) {
+ if (curr->hardirq_context)
+ if (!mark_lock(curr, hlock,
+ LOCK_USED_IN_HARDIRQ_READ, ip))
+ return 0;
+ if (curr->softirq_context)
+ if (!mark_lock(curr, hlock,
+ LOCK_USED_IN_SOFTIRQ_READ, ip))
+ return 0;
+ } else {
+ if (curr->hardirq_context)
+ if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ, ip))
+ return 0;
+ if (curr->softirq_context)
+ if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ, ip))
+ return 0;
+ }
+ }
+ if (!hardirqs_off) {
+ if (read) {
+ if (!mark_lock(curr, hlock,
+ LOCK_ENABLED_HARDIRQS_READ, ip))
+ return 0;
+ if (curr->softirqs_enabled)
+ if (!mark_lock(curr, hlock,
+ LOCK_ENABLED_SOFTIRQS_READ, ip))
+ return 0;
+ } else {
+ if (!mark_lock(curr, hlock,
+ LOCK_ENABLED_HARDIRQS, ip))
+ return 0;
+ if (curr->softirqs_enabled)
+ if (!mark_lock(curr, hlock,
+ LOCK_ENABLED_SOFTIRQS, ip))
+ return 0;
+ }
+ }
+#endif
+ /* mark it as used: */
+ if (!mark_lock(curr, hlock, LOCK_USED, ip))
+ return 0;
+out_calc_hash:
+ /*
+ * Calculate the chain hash: it's the combined has of all the
+ * lock keys along the dependency chain. We save the hash value
+ * at every step so that we can get the current hash easily
+ * after unlock. The chain hash is then used to cache dependency
+ * results.
+ *
+ * The 'key ID' is what is the most compact key value to drive
+ * the hash, not class->key.
+ */
+ id = class - lock_classes;
+ if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
+ return 0;
+
+ chain_key = curr->curr_chain_key;
+ if (!depth) {
+ if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
+ return 0;
+ chain_head = 1;
+ }
+
+ hlock->prev_chain_key = chain_key;
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ /*
+ * Keep track of points where we cross into an interrupt context:
+ */
+ hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +
+ curr->softirq_context;
+ if (depth) {
+ struct held_lock *prev_hlock;
+
+ prev_hlock = curr->held_locks + depth-1;
+ /*
+ * If we cross into another context, reset the
+ * hash key (this also prevents the checking and the
+ * adding of the dependency to 'prev'):
+ */
+ if (prev_hlock->irq_context != hlock->irq_context) {
+ chain_key = 0;
+ chain_head = 1;
+ }
+ }
+#endif
+ chain_key = iterate_chain_key(chain_key, id);
+ curr->curr_chain_key = chain_key;
+
+ /*
+ * Trylock needs to maintain the stack of held locks, but it
+ * does not add new dependencies, because trylock can be done
+ * in any order.
+ *
+ * We look up the chain_key and do the O(N^2) check and update of
+ * the dependencies only if this is a new dependency chain.
+ * (If lookup_chain_cache() returns with 1 it acquires
+ * hash_lock for us)
+ */
+ if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
+ /*
+ * Check whether last held lock:
+ *
+ * - is irq-safe, if this lock is irq-unsafe
+ * - is softirq-safe, if this lock is hardirq-unsafe
+ *
+ * And check whether the new lock's dependency graph
+ * could lead back to the previous lock.
+ *
+ * any of these scenarios could lead to a deadlock. If
+ * All validations
+ */
+ int ret = check_deadlock(curr, hlock, lock, read);
+
+ if (!ret)
+ return 0;
+ /*
+ * Mark recursive read, as we jump over it when
+ * building dependencies (just like we jump over
+ * trylock entries):
+ */
+ if (ret == 2)
+ hlock->read = 2;
+ /*
+ * Add dependency only if this lock is not the head
+ * of the chain, and if it's not a secondary read-lock:
+ */
+ if (!chain_head && ret != 2)
+ if (!check_prevs_add(curr, hlock))
+ return 0;
+ __raw_spin_unlock(&hash_lock);
+ }
+ curr->lockdep_depth++;
+ check_chain_key(curr);
+ if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
+ debug_locks_off();
+ printk("BUG: MAX_LOCK_DEPTH too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ return 0;
+ }
+ if (unlikely(curr->lockdep_depth > max_lockdep_depth))
+ max_lockdep_depth = curr->lockdep_depth;
+
+ return 1;
+}
+
+static int
+print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
+ unsigned long ip)
+{
+ if (!debug_locks_off())
+ return 0;
+ if (debug_locks_silent)
+ return 0;
+
+ printk("\n=====================================\n");
+ printk( "[ BUG: bad unlock balance detected! ]\n");
+ printk( "-------------------------------------\n");
+ printk("%s/%d is trying to release lock (",
+ curr->comm, curr->pid);
+ print_lockdep_cache(lock);
+ printk(") at:\n");
+ print_ip_sym(ip);
+ printk("but there are no more locks to release!\n");
+ printk("\nother info that might help us debug this:\n");
+ lockdep_print_held_locks(curr);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+
+ return 0;
+}
+
+/*
+ * Common debugging checks for both nested and non-nested unlock:
+ */
+static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
+ unsigned long ip)
+{
+ if (unlikely(!debug_locks))
+ return 0;
+ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
+ return 0;
+
+ if (curr->lockdep_depth <= 0)
+ return print_unlock_inbalance_bug(curr, lock, ip);
+
+ return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks in a
+ * potentially non-nested (out of order) manner. This is a
+ * relatively rare operation, as all the unlock APIs default
+ * to nested mode (which uses lock_release()):
+ */
+static int
+lock_release_non_nested(struct task_struct *curr,
+ struct lockdep_map *lock, unsigned long ip)
+{
+ struct held_lock *hlock, *prev_hlock;
+ unsigned int depth;
+ int i;
+
+ /*
+ * Check whether the lock exists in the current stack
+ * of held locks:
+ */
+ depth = curr->lockdep_depth;
+ if (DEBUG_LOCKS_WARN_ON(!depth))
+ return 0;
+
+ prev_hlock = NULL;
+ for (i = depth-1; i >= 0; i--) {
+ hlock = curr->held_locks + i;
+ /*
+ * We must not cross into another context:
+ */
+ if (prev_hlock && prev_hlock->irq_context != hlock->irq_context)
+ break;
+ if (hlock->instance == lock)
+ goto found_it;
+ prev_hlock = hlock;
+ }
+ return print_unlock_inbalance_bug(curr, lock, ip);
+
+found_it:
+ /*
+ * We have the right lock to unlock, 'hlock' points to it.
+ * Now we remove it from the stack, and add back the other
+ * entries (if any), recalculating the hash along the way:
+ */
+ curr->lockdep_depth = i;
+ curr->curr_chain_key = hlock->prev_chain_key;
+
+ for (i++; i < depth; i++) {
+ hlock = curr->held_locks + i;
+ if (!__lock_acquire(hlock->instance,
+ hlock->class->subclass, hlock->trylock,
+ hlock->read, hlock->check, hlock->hardirqs_off,
+ hlock->acquire_ip))
+ return 0;
+ }
+
+ if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
+ return 0;
+ return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()). This is done for unlocks that nest
+ * perfectly. (i.e. the current top of the lock-stack is unlocked)
+ */
+static int lock_release_nested(struct task_struct *curr,
+ struct lockdep_map *lock, unsigned long ip)
+{
+ struct held_lock *hlock;
+ unsigned int depth;
+
+ /*
+ * Pop off the top of the lock stack:
+ */
+ depth = curr->lockdep_depth - 1;
+ hlock = curr->held_locks + depth;
+
+ /*
+ * Is the unlock non-nested:
+ */
+ if (hlock->instance != lock)
+ return lock_release_non_nested(curr, lock, ip);
+ curr->lockdep_depth--;
+
+ if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
+ return 0;
+
+ curr->curr_chain_key = hlock->prev_chain_key;
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+ hlock->prev_chain_key = 0;
+ hlock->class = NULL;
+ hlock->acquire_ip = 0;
+ hlock->irq_context = 0;
+#endif
+ return 1;
+}
+
+/*
+ * Remove the lock to the list of currently held locks - this gets
+ * called on mutex_unlock()/spin_unlock*() (or on a failed
+ * mutex_lock_interruptible()). This is done for unlocks that nest
+ * perfectly. (i.e. the current top of the lock-stack is unlocked)
+ */
+static void
+__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
+{
+ struct task_struct *curr = current;
+
+ if (!check_unlock(curr, lock, ip))
+ return;
+
+ if (nested) {
+ if (!lock_release_nested(curr, lock, ip))
+ return;
+ } else {
+ if (!lock_release_non_nested(curr, lock, ip))
+ return;
+ }
+
+ check_chain_key(curr);
+}
+
+/*
+ * Check whether we follow the irq-flags state precisely:
+ */
+static void check_flags(unsigned long flags)
+{
+#if defined(CONFIG_DEBUG_LOCKDEP) && defined(CONFIG_TRACE_IRQFLAGS)
+ if (!debug_locks)
+ return;
+
+ if (irqs_disabled_flags(flags))
+ DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled);
+ else
+ DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled);
+
+ /*
+ * We dont accurately track softirq state in e.g.
+ * hardirq contexts (such as on 4KSTACKS), so only
+ * check if not in hardirq contexts:
+ */
+ if (!hardirq_count()) {
+ if (softirq_count())
+ DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
+ else
+ DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
+ }
+
+ if (!debug_locks)
+ print_irqtrace_events(current);
+#endif
+}
+
+/*
+ * We are not always called with irqs disabled - do that here,
+ * and also avoid lockdep recursion:
+ */
+void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
+ int trylock, int read, int check, unsigned long ip)
+{
+ unsigned long flags;
+
+ if (unlikely(current->lockdep_recursion))
+ return;
+
+ raw_local_irq_save(flags);
+ check_flags(flags);
+
+ current->lockdep_recursion = 1;
+ __lock_acquire(lock, subclass, trylock, read, check,
+ irqs_disabled_flags(flags), ip);
+ current->lockdep_recursion = 0;
+ raw_local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL_GPL(lock_acquire);
+
+void lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
+{
+ unsigned long flags;
+
+ if (unlikely(current->lockdep_recursion))
+ return;
+
+ raw_local_irq_save(flags);
+ check_flags(flags);
+ current->lockdep_recursion = 1;
+ __lock_release(lock, nested, ip);
+ current->lockdep_recursion = 0;
+ raw_local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL_GPL(lock_release);
+
+/*
+ * Used by the testsuite, sanitize the validator state
+ * after a simulated failure:
+ */
+
+void lockdep_reset(void)
+{
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+ current->curr_chain_key = 0;
+ current->lockdep_depth = 0;
+ current->lockdep_recursion = 0;
+ memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
+ nr_hardirq_chains = 0;
+ nr_softirq_chains = 0;
+ nr_process_chains = 0;
+ debug_locks = 1;
+ raw_local_irq_restore(flags);
+}
+
+static void zap_class(struct lock_class *class)
+{
+ int i;
+
+ /*
+ * Remove all dependencies this lock is
+ * involved in:
+ */
+ for (i = 0; i < nr_list_entries; i++) {
+ if (list_entries[i].class == class)
+ list_del_rcu(&list_entries[i].entry);
+ }
+ /*
+ * Unhash the class and remove it from the all_lock_classes list:
+ */
+ list_del_rcu(&class->hash_entry);
+ list_del_rcu(&class->lock_entry);
+
+}
+
+static inline int within(void *addr, void *start, unsigned long size)
+{
+ return addr >= start && addr < start + size;
+}
+
+void lockdep_free_key_range(void *start, unsigned long size)
+{
+ struct lock_class *class, *next;
+ struct list_head *head;
+ unsigned long flags;
+ int i;
+
+ raw_local_irq_save(flags);
+ __raw_spin_lock(&hash_lock);
+
+ /*
+ * Unhash all classes that were created by this module:
+ */
+ for (i = 0; i < CLASSHASH_SIZE; i++) {
+ head = classhash_table + i;
+ if (list_empty(head))
+ continue;
+ list_for_each_entry_safe(class, next, head, hash_entry)
+ if (within(class->key, start, size))
+ zap_class(class);
+ }
+
+ __raw_spin_unlock(&hash_lock);
+ raw_local_irq_restore(flags);
+}
+
+void lockdep_reset_lock(struct lockdep_map *lock)
+{
+ struct lock_class *class, *next;
+ struct list_head *head;
+ unsigned long flags;
+ int i, j;
+
+ raw_local_irq_save(flags);
+
+ /*
+ * Remove all classes this lock might have:
+ */
+ for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
+ /*
+ * If the class exists we look it up and zap it:
+ */
+ class = look_up_lock_class(lock, j);
+ if (class)
+ zap_class(class);
+ }
+ /*
+ * Debug check: in the end all mapped classes should
+ * be gone.
+ */
+ __raw_spin_lock(&hash_lock);
+ for (i = 0; i < CLASSHASH_SIZE; i++) {
+ head = classhash_table + i;
+ if (list_empty(head))
+ continue;
+ list_for_each_entry_safe(class, next, head, hash_entry) {
+ if (unlikely(class == lock->class_cache)) {
+ __raw_spin_unlock(&hash_lock);
+ DEBUG_LOCKS_WARN_ON(1);
+ goto out_restore;
+ }
+ }
+ }
+ __raw_spin_unlock(&hash_lock);
+
+out_restore:
+ raw_local_irq_restore(flags);
+}
+
+void __init lockdep_init(void)
+{
+ int i;
+
+ /*
+ * Some architectures have their own start_kernel()
+ * code which calls lockdep_init(), while we also
+ * call lockdep_init() from the start_kernel() itself,
+ * and we want to initialize the hashes only once:
+ */
+ if (lockdep_initialized)
+ return;
+
+ for (i = 0; i < CLASSHASH_SIZE; i++)
+ INIT_LIST_HEAD(classhash_table + i);
+
+ for (i = 0; i < CHAINHASH_SIZE; i++)
+ INIT_LIST_HEAD(chainhash_table + i);
+
+ lockdep_initialized = 1;
+}
+
+void __init lockdep_info(void)
+{
+ printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
+
+ printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
+ printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
+ printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
+ printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
+ printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
+ printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
+ printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
+
+ printk(" memory used by lock dependency info: %lu kB\n",
+ (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
+ sizeof(struct list_head) * CLASSHASH_SIZE +
+ sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
+ sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
+ sizeof(struct list_head) * CHAINHASH_SIZE) / 1024);
+
+ printk(" per task-struct memory footprint: %lu bytes\n",
+ sizeof(struct held_lock) * MAX_LOCK_DEPTH);
+
+#ifdef CONFIG_DEBUG_LOCKDEP
+ if (lockdep_init_error)
+ printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
+#endif
+}
+
+static inline int in_range(const void *start, const void *addr, const void *end)
+{
+ return addr >= start && addr <= end;
+}
+
+static void
+print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
+ const void *mem_to, struct held_lock *hlock)
+{
+ if (!debug_locks_off())
+ return;
+ if (debug_locks_silent)
+ return;
+
+ printk("\n=========================\n");
+ printk( "[ BUG: held lock freed! ]\n");
+ printk( "-------------------------\n");
+ printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
+ curr->comm, curr->pid, mem_from, mem_to-1);
+ print_lock(hlock);
+ lockdep_print_held_locks(curr);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+}
+
+/*
+ * Called when kernel memory is freed (or unmapped), or if a lock
+ * is destroyed or reinitialized - this code checks whether there is
+ * any held lock in the memory range of <from> to <to>:
+ */
+void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
+{
+ const void *mem_to = mem_from + mem_len, *lock_from, *lock_to;
+ struct task_struct *curr = current;
+ struct held_lock *hlock;
+ unsigned long flags;
+ int i;
+
+ if (unlikely(!debug_locks))
+ return;
+
+ local_irq_save(flags);
+ for (i = 0; i < curr->lockdep_depth; i++) {
+ hlock = curr->held_locks + i;
+
+ lock_from = (void *)hlock->instance;
+ lock_to = (void *)(hlock->instance + 1);
+
+ if (!in_range(mem_from, lock_from, mem_to) &&
+ !in_range(mem_from, lock_to, mem_to))
+ continue;
+
+ print_freed_lock_bug(curr, mem_from, mem_to, hlock);
+ break;
+ }
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
+
+static void print_held_locks_bug(struct task_struct *curr)
+{
+ if (!debug_locks_off())
+ return;
+ if (debug_locks_silent)
+ return;
+
+ printk("\n=====================================\n");
+ printk( "[ BUG: lock held at task exit time! ]\n");
+ printk( "-------------------------------------\n");
+ printk("%s/%d is exiting with locks still held!\n",
+ curr->comm, curr->pid);
+ lockdep_print_held_locks(curr);
+
+ printk("\nstack backtrace:\n");
+ dump_stack();
+}
+
+void debug_check_no_locks_held(struct task_struct *task)
+{
+ if (unlikely(task->lockdep_depth > 0))
+ print_held_locks_bug(task);
+}
+
+void debug_show_all_locks(void)
+{
+ struct task_struct *g, *p;
+ int count = 10;
+ int unlock = 1;
+
+ printk("\nShowing all locks held in the system:\n");
+
+ /*
+ * Here we try to get the tasklist_lock as hard as possible,
+ * if not successful after 2 seconds we ignore it (but keep
+ * trying). This is to enable a debug printout even if a
+ * tasklist_lock-holding task deadlocks or crashes.
+ */
+retry:
+ if (!read_trylock(&tasklist_lock)) {
+ if (count == 10)
+ printk("hm, tasklist_lock locked, retrying... ");
+ if (count) {
+ count--;
+ printk(" #%d", 10-count);
+ mdelay(200);
+ goto retry;
+ }
+ printk(" ignoring it.\n");
+ unlock = 0;
+ }
+ if (count != 10)
+ printk(" locked it.\n");
+
+ do_each_thread(g, p) {
+ if (p->lockdep_depth)
+ lockdep_print_held_locks(p);
+ if (!unlock)
+ if (read_trylock(&tasklist_lock))
+ unlock = 1;
+ } while_each_thread(g, p);
+
+ printk("\n");
+ printk("=============================================\n\n");
+
+ if (unlock)
+ read_unlock(&tasklist_lock);
+}
+
+EXPORT_SYMBOL_GPL(debug_show_all_locks);
+
+void debug_show_held_locks(struct task_struct *task)
+{
+ lockdep_print_held_locks(task);
+}
+
+EXPORT_SYMBOL_GPL(debug_show_held_locks);
+
git://git.onelab.eu / linux-2.6.git / blobdiff