* to allow signals to be sent reliably.
*/
+#include <linux/config.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
+#include <linux/posix-timers.h>
#include <linux/signal.h>
+#include <linux/audit.h>
#include <linux/capability.h>
+#include <linux/vs_cvirt.h>
#include <asm/param.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/siginfo.h>
-#include "audit.h" /* audit_signal_info() */
/*
* SLAB caches for signal bits.
#define sig_kernel_stop(sig) \
(((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
-#define sig_needs_tasklist(sig) ((sig) == SIGCONT)
-
#define sig_user_defined(t, signr) \
(((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
kmem_cache_free(sigqueue_cachep, q);
}
-void flush_sigqueue(struct sigpending *queue)
+static void flush_sigqueue(struct sigpending *queue)
{
struct sigqueue *q;
/*
* Flush all pending signals for a task.
*/
-void flush_signals(struct task_struct *t)
+
+void
+flush_signals(struct task_struct *t)
{
unsigned long flags;
spin_unlock_irqrestore(&t->sighand->siglock, flags);
}
+/*
+ * This function expects the tasklist_lock write-locked.
+ */
+void __exit_sighand(struct task_struct *tsk)
+{
+ struct sighand_struct * sighand = tsk->sighand;
+
+ /* Ok, we're done with the signal handlers */
+ tsk->sighand = NULL;
+ if (atomic_dec_and_test(&sighand->count))
+ sighand_free(sighand);
+}
+
+void exit_sighand(struct task_struct *tsk)
+{
+ write_lock_irq(&tasklist_lock);
+ rcu_read_lock();
+ if (tsk->sighand != NULL) {
+ struct sighand_struct *sighand = rcu_dereference(tsk->sighand);
+ spin_lock(&sighand->siglock);
+ __exit_sighand(tsk);
+ spin_unlock(&sighand->siglock);
+ }
+ rcu_read_unlock();
+ write_unlock_irq(&tasklist_lock);
+}
+
+/*
+ * This function expects the tasklist_lock write-locked.
+ */
+void __exit_signal(struct task_struct *tsk)
+{
+ struct signal_struct * sig = tsk->signal;
+ struct sighand_struct * sighand;
+
+ if (!sig)
+ BUG();
+ if (!atomic_read(&sig->count))
+ BUG();
+ rcu_read_lock();
+ sighand = rcu_dereference(tsk->sighand);
+ spin_lock(&sighand->siglock);
+ posix_cpu_timers_exit(tsk);
+ if (atomic_dec_and_test(&sig->count)) {
+ posix_cpu_timers_exit_group(tsk);
+ tsk->signal = NULL;
+ __exit_sighand(tsk);
+ spin_unlock(&sighand->siglock);
+ flush_sigqueue(&sig->shared_pending);
+ } else {
+ /*
+ * If there is any task waiting for the group exit
+ * then notify it:
+ */
+ if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
+ wake_up_process(sig->group_exit_task);
+ sig->group_exit_task = NULL;
+ }
+ if (tsk == sig->curr_target)
+ sig->curr_target = next_thread(tsk);
+ tsk->signal = NULL;
+ /*
+ * Accumulate here the counters for all threads but the
+ * group leader as they die, so they can be added into
+ * the process-wide totals when those are taken.
+ * The group leader stays around as a zombie as long
+ * as there are other threads. When it gets reaped,
+ * the exit.c code will add its counts into these totals.
+ * We won't ever get here for the group leader, since it
+ * will have been the last reference on the signal_struct.
+ */
+ sig->utime = cputime_add(sig->utime, tsk->utime);
+ sig->stime = cputime_add(sig->stime, tsk->stime);
+ sig->min_flt += tsk->min_flt;
+ sig->maj_flt += tsk->maj_flt;
+ sig->nvcsw += tsk->nvcsw;
+ sig->nivcsw += tsk->nivcsw;
+ sig->sched_time += tsk->sched_time;
+ __exit_sighand(tsk);
+ spin_unlock(&sighand->siglock);
+ sig = NULL; /* Marker for below. */
+ }
+ rcu_read_unlock();
+ clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
+ flush_sigqueue(&tsk->pending);
+ if (sig) {
+ /*
+ * We are cleaning up the signal_struct here.
+ */
+ exit_thread_group_keys(sig);
+ kmem_cache_free(signal_cachep, sig);
+ }
+}
+
+void exit_signal(struct task_struct *tsk)
+{
+ atomic_dec(&tsk->signal->live);
+
+ write_lock_irq(&tasklist_lock);
+ __exit_signal(tsk);
+ write_unlock_irq(&tasklist_lock);
+}
+
/*
* Flush all handlers for a task.
*/
}
}
-EXPORT_SYMBOL_GPL(flush_signal_handlers);
/* Notify the system that a driver wants to block all signals for this
* process, and wants to be notified if any signals at all were to be
if (user && !vx_check(vx_task_xid(t), VX_ADMIN|VX_IDENT))
return error;
- error = security_task_kill(t, info, sig, 0);
+ error = security_task_kill(t, info, sig);
if (!error)
audit_signal_info(sig, t); /* Let audit system see the signal */
return error;
}
/* forward decl */
-static void do_notify_parent_cldstop(struct task_struct *tsk, int why);
+static void do_notify_parent_cldstop(struct task_struct *tsk,
+ int to_self,
+ int why);
/*
* Handle magic process-wide effects of stop/continue signals.
p->signal->group_stop_count = 0;
p->signal->flags = SIGNAL_STOP_CONTINUED;
spin_unlock(&p->sighand->siglock);
- do_notify_parent_cldstop(p, CLD_STOPPED);
+ do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED);
spin_lock(&p->sighand->siglock);
}
rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
p->signal->flags = SIGNAL_STOP_CONTINUED;
p->signal->group_exit_code = 0;
spin_unlock(&p->sighand->siglock);
- do_notify_parent_cldstop(p, CLD_CONTINUED);
+ do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED);
spin_lock(&p->sighand->siglock);
} else {
/*
#define LEGACY_QUEUE(sigptr, sig) \
(((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
-int print_fatal_signals = 0;
-
-static void print_fatal_signal(struct pt_regs *regs, int signr)
-{
- printk("%s/%d: potentially unexpected fatal signal %d.\n",
- current->comm, current->pid, signr);
-
-#ifdef __i386__
- printk("code at %08lx: ", regs->eip);
- {
- int i;
- for (i = 0; i < 16; i++) {
- unsigned char insn;
-
- __get_user(insn, (unsigned char *)(regs->eip + i));
- printk("%02x ", insn);
- }
- }
-#endif
- printk("\n");
- show_regs(regs);
-}
-
-static int __init setup_print_fatal_signals(char *str)
-{
- get_option (&str, &print_fatal_signals);
-
- return 1;
-}
-
-__setup("print-fatal-signals=", setup_print_fatal_signals);
static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
int ret = 0;
- BUG_ON(!irqs_disabled());
+ if (!irqs_disabled())
+ BUG();
assert_spin_locked(&t->sighand->siglock);
/* Short-circuit ignored signals. */
/*
* Force a signal that the process can't ignore: if necessary
* we unblock the signal and change any SIG_IGN to SIG_DFL.
- *
- * Note: If we unblock the signal, we always reset it to SIG_DFL,
- * since we do not want to have a signal handler that was blocked
- * be invoked when user space had explicitly blocked it.
- *
- * We don't want to have recursive SIGSEGV's etc, for example.
*/
+
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
unsigned long int flags;
- int ret, blocked, ignored;
- struct k_sigaction *action;
+ int ret;
spin_lock_irqsave(&t->sighand->siglock, flags);
- action = &t->sighand->action[sig-1];
- ignored = action->sa.sa_handler == SIG_IGN;
- blocked = sigismember(&t->blocked, sig);
- if (blocked || ignored) {
- action->sa.sa_handler = SIG_DFL;
- if (blocked) {
- sigdelset(&t->blocked, sig);
- recalc_sigpending_tsk(t);
- }
+ if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
+ t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
}
+ if (sigismember(&t->blocked, sig)) {
+ sigdelset(&t->blocked, sig);
+ }
+ recalc_sigpending_tsk(t);
ret = specific_send_sig_info(sig, info, t);
spin_unlock_irqrestore(&t->sighand->siglock, flags);
/*
* Must be called under rcu_read_lock() or with tasklist_lock read-held.
*/
-struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
-{
- struct sighand_struct *sighand;
-
- for (;;) {
- sighand = rcu_dereference(tsk->sighand);
- if (unlikely(sighand == NULL))
- break;
-
- spin_lock_irqsave(&sighand->siglock, *flags);
- if (likely(sighand == tsk->sighand))
- break;
- spin_unlock_irqrestore(&sighand->siglock, *flags);
- }
-
- return sighand;
-}
-
int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
unsigned long flags;
+ struct sighand_struct *sp;
int ret;
+retry:
ret = check_kill_permission(sig, info, p);
-
- if (!ret && sig) {
- ret = -ESRCH;
- if (lock_task_sighand(p, &flags)) {
- ret = __group_send_sig_info(sig, info, p);
- unlock_task_sighand(p, &flags);
+ if (!ret && sig && (sp = rcu_dereference(p->sighand))) {
+ spin_lock_irqsave(&sp->siglock, flags);
+ if (p->sighand != sp) {
+ spin_unlock_irqrestore(&sp->siglock, flags);
+ goto retry;
+ }
+ if ((atomic_read(&sp->count) == 0) ||
+ (atomic_read(&p->usage) == 0)) {
+ spin_unlock_irqrestore(&sp->siglock, flags);
+ return -ESRCH;
}
+ ret = __group_send_sig_info(sig, info, p);
+ spin_unlock_irqrestore(&sp->siglock, flags);
}
return ret;
struct task_struct *p;
rcu_read_lock();
- if (unlikely(sig_needs_tasklist(sig))) {
+ if (unlikely(sig_kernel_stop(sig) || sig == SIGCONT)) {
read_lock(&tasklist_lock);
acquired_tasklist_lock = 1;
}
/* like kill_proc_info(), but doesn't use uid/euid of "current" */
int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
- uid_t uid, uid_t euid, u32 secid)
+ uid_t uid, uid_t euid)
{
int ret = -EINVAL;
struct task_struct *p;
ret = -EPERM;
goto out_unlock;
}
- ret = security_task_kill(p, info, sig, secid);
- if (ret)
- goto out_unlock;
if (sig && p->sighand) {
unsigned long flags;
spin_lock_irqsave(&p->sighand->siglock, flags);
read_lock(&tasklist_lock);
for_each_process(p) {
- if (vx_check(vx_task_xid(p), VX_ADMIN|VX_IDENT) &&
+ if (vx_check(vx_task_xid(p), VX_ADMIN|VX_IDENT)&&
p->pid > 1 && p->tgid != current->tgid) {
int err = group_send_sig_info(sig, info, p);
++count;
__sigqueue_free(q);
}
-int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
+int
+send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
{
unsigned long flags;
int ret = 0;
+ struct sighand_struct *sh;
BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
*/
rcu_read_lock();
- if (!likely(lock_task_sighand(p, &flags))) {
+ if (unlikely(p->flags & PF_EXITING)) {
ret = -1;
goto out_err;
}
+retry:
+ sh = rcu_dereference(p->sighand);
+
+ spin_lock_irqsave(&sh->siglock, flags);
+ if (p->sighand != sh) {
+ /* We raced with exec() in a multithreaded process... */
+ spin_unlock_irqrestore(&sh->siglock, flags);
+ goto retry;
+ }
+
+ /*
+ * We do the check here again to handle the following scenario:
+ *
+ * CPU 0 CPU 1
+ * send_sigqueue
+ * check PF_EXITING
+ * interrupt exit code running
+ * __exit_signal
+ * lock sighand->siglock
+ * unlock sighand->siglock
+ * lock sh->siglock
+ * add(tsk->pending) flush_sigqueue(tsk->pending)
+ *
+ */
+
+ if (unlikely(p->flags & PF_EXITING)) {
+ ret = -1;
+ goto out;
+ }
+
if (unlikely(!list_empty(&q->list))) {
/*
* If an SI_TIMER entry is already queue just increment
* the overrun count.
*/
- BUG_ON(q->info.si_code != SI_TIMER);
+ if (q->info.si_code != SI_TIMER)
+ BUG();
q->info.si_overrun++;
goto out;
}
signal_wake_up(p, sig == SIGKILL);
out:
- unlock_task_sighand(p, &flags);
+ spin_unlock_irqrestore(&sh->siglock, flags);
out_err:
rcu_read_unlock();
* the overrun count. Other uses should not try to
* send the signal multiple times.
*/
- BUG_ON(q->info.si_code != SI_TIMER);
+ if (q->info.si_code != SI_TIMER)
+ BUG();
q->info.si_overrun++;
goto out;
}
spin_unlock_irqrestore(&psig->siglock, flags);
}
-static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
+static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why)
{
struct siginfo info;
unsigned long flags;
struct task_struct *parent;
struct sighand_struct *sighand;
- if (tsk->ptrace & PT_PTRACED)
+ if (to_self)
parent = tsk->parent;
else {
tsk = tsk->group_leader;
spin_unlock_irqrestore(&sighand->siglock, flags);
}
-static inline int may_ptrace_stop(void)
-{
- if (!likely(current->ptrace & PT_PTRACED))
- return 0;
-
- if (unlikely(current->parent == current->real_parent &&
- (current->ptrace & PT_ATTACHED)))
- return 0;
-
- if (unlikely(current->signal == current->parent->signal) &&
- unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))
- return 0;
-
- /*
- * Are we in the middle of do_coredump?
- * If so and our tracer is also part of the coredump stopping
- * is a deadlock situation, and pointless because our tracer
- * is dead so don't allow us to stop.
- * If SIGKILL was already sent before the caller unlocked
- * ->siglock we must see ->core_waiters != 0. Otherwise it
- * is safe to enter schedule().
- */
- if (unlikely(current->mm->core_waiters) &&
- unlikely(current->mm == current->parent->mm))
- return 0;
-
- return 1;
-}
-
/*
* This must be called with current->sighand->siglock held.
*
spin_unlock_irq(¤t->sighand->siglock);
try_to_freeze();
read_lock(&tasklist_lock);
- if (may_ptrace_stop()) {
- do_notify_parent_cldstop(current, CLD_TRAPPED);
+ if (likely(current->ptrace & PT_PTRACED) &&
+ likely(current->parent != current->real_parent ||
+ !(current->ptrace & PT_ATTACHED)) &&
+ (likely(current->parent->signal != current->signal) ||
+ !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
+ do_notify_parent_cldstop(current, 1, CLD_TRAPPED);
read_unlock(&tasklist_lock);
schedule();
} else {
static void
finish_stop(int stop_count)
{
+ int to_self;
+
/*
* If there are no other threads in the group, or if there is
* a group stop in progress and we are the last to stop,
* report to the parent. When ptraced, every thread reports itself.
*/
- if (stop_count == 0 || (current->ptrace & PT_PTRACED)) {
- read_lock(&tasklist_lock);
- do_notify_parent_cldstop(current, CLD_STOPPED);
- read_unlock(&tasklist_lock);
- }
+ if (stop_count < 0 || (current->ptrace & PT_PTRACED))
+ to_self = 1;
+ else if (stop_count == 0)
+ to_self = 0;
+ else
+ goto out;
+
+ read_lock(&tasklist_lock);
+ do_notify_parent_cldstop(current, to_self, CLD_STOPPED);
+ read_unlock(&tasklist_lock);
+out:
schedule();
/*
* Now we don't run again until continued.
* Returns nonzero if we've actually stopped and released the siglock.
* Returns zero if we didn't stop and still hold the siglock.
*/
-static int do_signal_stop(int signr)
+static int
+do_signal_stop(int signr)
{
struct signal_struct *sig = current->signal;
- int stop_count;
+ struct sighand_struct *sighand = current->sighand;
+ int stop_count = -1;
if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
return 0;
* There is a group stop in progress. We don't need to
* start another one.
*/
+ signr = sig->group_exit_code;
stop_count = --sig->group_stop_count;
- } else {
+ current->exit_code = signr;
+ set_current_state(TASK_STOPPED);
+ if (stop_count == 0)
+ sig->flags = SIGNAL_STOP_STOPPED;
+ spin_unlock_irq(&sighand->siglock);
+ }
+ else if (thread_group_empty(current)) {
+ /*
+ * Lock must be held through transition to stopped state.
+ */
+ current->exit_code = current->signal->group_exit_code = signr;
+ set_current_state(TASK_STOPPED);
+ sig->flags = SIGNAL_STOP_STOPPED;
+ spin_unlock_irq(&sighand->siglock);
+ }
+ else {
/*
* There is no group stop already in progress.
- * We must initiate one now.
+ * We must initiate one now, but that requires
+ * dropping siglock to get both the tasklist lock
+ * and siglock again in the proper order. Note that
+ * this allows an intervening SIGCONT to be posted.
+ * We need to check for that and bail out if necessary.
*/
struct task_struct *t;
- sig->group_exit_code = signr;
+ spin_unlock_irq(&sighand->siglock);
+
+ /* signals can be posted during this window */
- stop_count = 0;
- for (t = next_thread(current); t != current; t = next_thread(t))
+ read_lock(&tasklist_lock);
+ spin_lock_irq(&sighand->siglock);
+
+ if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
/*
- * Setting state to TASK_STOPPED for a group
- * stop is always done with the siglock held,
- * so this check has no races.
+ * Another stop or continue happened while we
+ * didn't have the lock. We can just swallow this
+ * signal now. If we raced with a SIGCONT, that
+ * should have just cleared it now. If we raced
+ * with another processor delivering a stop signal,
+ * then the SIGCONT that wakes us up should clear it.
*/
- if (!t->exit_state &&
- !(t->state & (TASK_STOPPED|TASK_TRACED))) {
- stop_count++;
- signal_wake_up(t, 0);
- }
- sig->group_stop_count = stop_count;
- }
+ read_unlock(&tasklist_lock);
+ return 0;
+ }
- if (stop_count == 0)
- sig->flags = SIGNAL_STOP_STOPPED;
- current->exit_code = sig->group_exit_code;
- __set_current_state(TASK_STOPPED);
+ if (sig->group_stop_count == 0) {
+ sig->group_exit_code = signr;
+ stop_count = 0;
+ for (t = next_thread(current); t != current;
+ t = next_thread(t))
+ /*
+ * Setting state to TASK_STOPPED for a group
+ * stop is always done with the siglock held,
+ * so this check has no races.
+ */
+ if (!t->exit_state &&
+ !(t->state & (TASK_STOPPED|TASK_TRACED))) {
+ stop_count++;
+ signal_wake_up(t, 0);
+ }
+ sig->group_stop_count = stop_count;
+ }
+ else {
+ /* A race with another thread while unlocked. */
+ signr = sig->group_exit_code;
+ stop_count = --sig->group_stop_count;
+ }
+
+ current->exit_code = signr;
+ set_current_state(TASK_STOPPED);
+ if (stop_count == 0)
+ sig->flags = SIGNAL_STOP_STOPPED;
+
+ spin_unlock_irq(&sighand->siglock);
+ read_unlock(&tasklist_lock);
+ }
- spin_unlock_irq(¤t->sighand->siglock);
finish_stop(stop_count);
return 1;
}
sigset_t *mask = ¤t->blocked;
int signr = 0;
- try_to_freeze();
-
relock:
spin_lock_irq(¤t->sighand->siglock);
for (;;) {
continue;
/* Init gets no signals it doesn't want. */
- if (current == child_reaper)
+ if (current->pid == 1)
continue;
/* virtual init is protected against user signals */
* Anything else is fatal, maybe with a core dump.
*/
current->flags |= PF_SIGNALED;
- if (print_fatal_signals)
- print_fatal_signal(regs, signr);
if (sig_kernel_coredump(signr)) {
/*
* If it was able to dump core, this kills all
int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
{
int error;
+ sigset_t old_block;
spin_lock_irq(¤t->sighand->siglock);
- if (oldset)
- *oldset = current->blocked;
-
+ old_block = current->blocked;
error = 0;
switch (how) {
case SIG_BLOCK:
}
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
-
+ if (oldset)
+ *oldset = old_block;
return error;
}
timeout = schedule_timeout_interruptible(timeout);
+ try_to_freeze();
spin_lock_irq(¤t->sighand->siglock);
sig = dequeue_signal(current, &these, &info);
current->blocked = current->real_blocked;
return kill_proc_info(sig, &info, pid);
}
-int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
+int
+do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
{
struct k_sigaction *k;
sigset_t mask;
if (act) {
sigdelsetmask(&act->sa.sa_mask,
sigmask(SIGKILL) | sigmask(SIGSTOP));
- *k = *act;
/*
* POSIX 3.3.1.3:
* "Setting a signal action to SIG_IGN for a signal that is
* be discarded, whether or not it is blocked"
*/
if (act->sa.sa_handler == SIG_IGN ||
- (act->sa.sa_handler == SIG_DFL && sig_kernel_ignore(sig))) {
+ (act->sa.sa_handler == SIG_DFL &&
+ sig_kernel_ignore(sig))) {
+ /*
+ * This is a fairly rare case, so we only take the
+ * tasklist_lock once we're sure we'll need it.
+ * Now we must do this little unlock and relock
+ * dance to maintain the lock hierarchy.
+ */
struct task_struct *t = current;
+ spin_unlock_irq(&t->sighand->siglock);
+ read_lock(&tasklist_lock);
+ spin_lock_irq(&t->sighand->siglock);
+ *k = *act;
sigemptyset(&mask);
sigaddset(&mask, sig);
rm_from_queue_full(&mask, &t->signal->shared_pending);
recalc_sigpending_tsk(t);
t = next_thread(t);
} while (t != current);
+ spin_unlock_irq(¤t->sighand->siglock);
+ read_unlock(&tasklist_lock);
+ return 0;
}
+
+ *k = *act;
}
spin_unlock_irq(¤t->sighand->siglock);
git://git.onelab.eu / linux-2.6.git / blobdiff