linux 2.6.16.38 w/ vs2.0.3-rc1
[linux-2.6.git] / kernel / pid.c
index 5eeb505..a864bf8 100644 (file)
@@ -29,9 +29,8 @@
 #include <linux/vs_cvirt.h>
 
 #define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
-static struct hlist_head *pid_hash;
+static struct hlist_head *pid_hash[PIDTYPE_MAX];
 static int pidhash_shift;
-static kmem_cache_t *pid_cachep;
 
 int pid_max = PID_MAX_DEFAULT;
 int last_pid;
@@ -62,22 +61,9 @@ typedef struct pidmap {
 static pidmap_t pidmap_array[PIDMAP_ENTRIES] =
         { [ 0 ... PIDMAP_ENTRIES-1 ] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } };
 
-/*
- * Note: disable interrupts while the pidmap_lock is held as an
- * interrupt might come in and do read_lock(&tasklist_lock).
- *
- * If we don't disable interrupts there is a nasty deadlock between
- * detach_pid()->free_pid() and another cpu that does
- * spin_lock(&pidmap_lock) followed by an interrupt routine that does
- * read_lock(&tasklist_lock);
- *
- * After we clean up the tasklist_lock and know there are no
- * irq handlers that take it we can leave the interrupts enabled.
- * For now it is easier to be safe than to prove it can't happen.
- */
 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
 
-static fastcall void free_pidmap(int pid)
+fastcall void free_pidmap(int pid)
 {
        pidmap_t *map = pidmap_array + pid / BITS_PER_PAGE;
        int offset = pid & BITS_PER_PAGE_MASK;
@@ -86,7 +72,7 @@ static fastcall void free_pidmap(int pid)
        atomic_inc(&map->nr_free);
 }
 
-static int alloc_pidmap(void)
+int alloc_pidmap(void)
 {
        int i, offset, max_scan, pid, last = last_pid;
        pidmap_t *map;
@@ -104,12 +90,12 @@ static int alloc_pidmap(void)
                         * Free the page if someone raced with us
                         * installing it:
                         */
-                       spin_lock_irq(&pidmap_lock);
+                       spin_lock(&pidmap_lock);
                        if (map->page)
                                free_page(page);
                        else
                                map->page = (void *)page;
-                       spin_unlock_irq(&pidmap_lock);
+                       spin_unlock(&pidmap_lock);
                        if (unlikely(!map->page))
                                break;
                }
@@ -146,167 +132,125 @@ static int alloc_pidmap(void)
        return -1;
 }
 
-fastcall void put_pid(struct pid *pid)
-{
-       if (!pid)
-               return;
-       if ((atomic_read(&pid->count) == 1) ||
-            atomic_dec_and_test(&pid->count))
-               kmem_cache_free(pid_cachep, pid);
-}
-
-static void delayed_put_pid(struct rcu_head *rhp)
-{
-       struct pid *pid = container_of(rhp, struct pid, rcu);
-       put_pid(pid);
-}
-
-fastcall void free_pid(struct pid *pid)
-{
-       /* We can be called with write_lock_irq(&tasklist_lock) held */
-       unsigned long flags;
-
-       spin_lock_irqsave(&pidmap_lock, flags);
-       hlist_del_rcu(&pid->pid_chain);
-       spin_unlock_irqrestore(&pidmap_lock, flags);
-
-       free_pidmap(pid->nr);
-       call_rcu(&pid->rcu, delayed_put_pid);
-}
-
-struct pid *alloc_pid(void)
-{
-       struct pid *pid;
-       enum pid_type type;
-       int nr = -1;
-
-       pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
-       if (!pid)
-               goto out;
-
-       nr = alloc_pidmap();
-       if (nr < 0)
-               goto out_free;
-
-       atomic_set(&pid->count, 1);
-       pid->nr = nr;
-       for (type = 0; type < PIDTYPE_MAX; ++type)
-               INIT_HLIST_HEAD(&pid->tasks[type]);
-
-       spin_lock_irq(&pidmap_lock);
-       hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]);
-       spin_unlock_irq(&pidmap_lock);
-
-out:
-       return pid;
-
-out_free:
-       kmem_cache_free(pid_cachep, pid);
-       pid = NULL;
-       goto out;
-}
-
-struct pid * fastcall find_pid(int nr)
+struct pid * fastcall find_pid(enum pid_type type, int nr)
 {
        struct hlist_node *elem;
        struct pid *pid;
 
        hlist_for_each_entry_rcu(pid, elem,
-                       &pid_hash[pid_hashfn(nr)], pid_chain) {
+                       &pid_hash[type][pid_hashfn(nr)], pid_chain) {
                if (pid->nr == nr)
                        return pid;
        }
        return NULL;
 }
 
-int fastcall attach_pid(struct task_struct *task, enum pid_type type, int nr)
+int fastcall attach_pid(task_t *task, enum pid_type type, int nr)
 {
-       struct pid_link *link;
-       struct pid *pid;
-
-       WARN_ON(!task->pid); /* to be removed soon */
-       WARN_ON(!nr); /* to be removed soon */
-
-       link = &task->pids[type];
-       link->pid = pid = find_pid(nr);
-       hlist_add_head_rcu(&link->node, &pid->tasks[type]);
+       struct pid *pid, *task_pid;
+
+       task_pid = &task->pids[type];
+       pid = find_pid(type, nr);
+       task_pid->nr = nr;
+       if (pid == NULL) {
+               INIT_LIST_HEAD(&task_pid->pid_list);
+               hlist_add_head_rcu(&task_pid->pid_chain,
+                                  &pid_hash[type][pid_hashfn(nr)]);
+       } else {
+               INIT_HLIST_NODE(&task_pid->pid_chain);
+               list_add_tail_rcu(&task_pid->pid_list, &pid->pid_list);
+       }
 
        return 0;
 }
 
-void fastcall detach_pid(struct task_struct *task, enum pid_type type)
+static fastcall int __detach_pid(task_t *task, enum pid_type type)
 {
-       struct pid_link *link;
-       struct pid *pid;
-       int tmp;
+       struct pid *pid, *pid_next;
+       int nr = 0;
 
-       link = &task->pids[type];
-       pid = link->pid;
+       pid = &task->pids[type];
+       if (!hlist_unhashed(&pid->pid_chain)) {
 
-       hlist_del_rcu(&link->node);
-       link->pid = NULL;
+               if (list_empty(&pid->pid_list)) {
+                       nr = pid->nr;
+                       hlist_del_rcu(&pid->pid_chain);
+               } else {
+                       pid_next = list_entry(pid->pid_list.next,
+                                               struct pid, pid_list);
+                       /* insert next pid from pid_list to hash */
+                       hlist_replace_rcu(&pid->pid_chain,
+                                         &pid_next->pid_chain);
+               }
+       }
 
-       for (tmp = PIDTYPE_MAX; --tmp >= 0; )
-               if (!hlist_empty(&pid->tasks[tmp]))
-                       return;
+       list_del_rcu(&pid->pid_list);
+       pid->nr = 0;
 
-       free_pid(pid);
+       return nr;
 }
 
-struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
+void fastcall detach_pid(task_t *task, enum pid_type type)
 {
-       struct task_struct *result = NULL;
-       if (pid) {
-               struct hlist_node *first;
-               first = rcu_dereference(pid->tasks[type].first);
-               if (first)
-                       result = hlist_entry(first, struct task_struct, pids[(type)].node);
-               if (result && (pid->nr != 1) &&
-                       !vx_check(vx_task_xid(result), VX_WATCH|VX_ADMIN|VX_IDENT)) {
-                       vxwprintk((type == PIDTYPE_PID) && (current->xid),
-                               "pid_task(%d,%d): task %p[#%u,%u] did lookup %p[#%u,%u]",
-                               pid->nr, type, current, vx_current_xid(), current->pid,
-                               result, vx_task_xid(result), result->pid);
-                       result = NULL;
-               }
-       }
-       return result;
-}
+       int tmp, nr;
 
-/*
- * Must be called under rcu_read_lock() or with tasklist_lock read-held.
- */
-struct task_struct *find_task_by_pid_type(int type, int nr)
-{
-       if (type == PIDTYPE_PID)
-               nr = vx_rmap_pid(nr);
-       else if (type == PIDTYPE_REALPID)
-               type = PIDTYPE_PID;
-       return pid_task(find_pid(nr), type);
-}
+       nr = __detach_pid(task, type);
+       if (!nr)
+               return;
 
-EXPORT_SYMBOL(find_task_by_pid_type);
+       for (tmp = PIDTYPE_MAX; --tmp >= 0; )
+               if (tmp != type && find_pid(tmp, nr))
+                       return;
 
-struct task_struct *fastcall get_pid_task(struct pid *pid, enum pid_type type)
-{
-       struct task_struct *result;
-       rcu_read_lock();
-       result = pid_task(pid, type);
-       if (result)
-               get_task_struct(result);
-       rcu_read_unlock();
-       return result;
+       free_pidmap(nr);
 }
 
-struct pid *find_get_pid(pid_t nr)
+task_t *find_task_by_pid_type(int type, int nr)
 {
        struct pid *pid;
 
-       rcu_read_lock();
-       pid = get_pid(find_pid(nr));
-       rcu_read_unlock();
+       if (type == PIDTYPE_REALPID)
+               type = PIDTYPE_PID;
+       else if (type == PIDTYPE_PID)
+               nr = vx_rmap_pid(nr);
+
+       pid = find_pid(type, nr);
+       if (!pid)
+               return NULL;
+
+       return pid_task(&pid->pid_list, type);
+}
+
+EXPORT_SYMBOL(find_task_by_pid_type);
 
-       return pid;
+/*
+ * This function switches the PIDs if a non-leader thread calls
+ * sys_execve() - this must be done without releasing the PID.
+ * (which a detach_pid() would eventually do.)
+ */
+void switch_exec_pids(task_t *leader, task_t *thread)
+{
+       __detach_pid(leader, PIDTYPE_PID);
+       __detach_pid(leader, PIDTYPE_TGID);
+       __detach_pid(leader, PIDTYPE_PGID);
+       __detach_pid(leader, PIDTYPE_SID);
+
+       __detach_pid(thread, PIDTYPE_PID);
+       __detach_pid(thread, PIDTYPE_TGID);
+
+       leader->pid = leader->tgid = thread->pid;
+       thread->pid = thread->tgid;
+
+       attach_pid(thread, PIDTYPE_PID, thread->pid);
+       attach_pid(thread, PIDTYPE_TGID, thread->tgid);
+       attach_pid(thread, PIDTYPE_PGID, thread->signal->pgrp);
+       attach_pid(thread, PIDTYPE_SID, thread->signal->session);
+       list_add_tail(&thread->tasks, &init_task.tasks);
+
+       attach_pid(leader, PIDTYPE_PID, leader->pid);
+       attach_pid(leader, PIDTYPE_TGID, leader->tgid);
+       attach_pid(leader, PIDTYPE_PGID, leader->signal->pgrp);
+       attach_pid(leader, PIDTYPE_SID, leader->signal->session);
 }
 
 /*
@@ -316,7 +260,7 @@ struct pid *find_get_pid(pid_t nr)
  */
 void __init pidhash_init(void)
 {
-       int i, pidhash_size;
+       int i, j, pidhash_size;
        unsigned long megabytes = nr_kernel_pages >> (20 - PAGE_SHIFT);
 
        pidhash_shift = max(4, fls(megabytes * 4));
@@ -325,23 +269,30 @@ void __init pidhash_init(void)
 
        printk("PID hash table entries: %d (order: %d, %Zd bytes)\n",
                pidhash_size, pidhash_shift,
-               pidhash_size * sizeof(struct hlist_head));
-
-       pid_hash = alloc_bootmem(pidhash_size * sizeof(*(pid_hash)));
-       if (!pid_hash)
-               panic("Could not alloc pidhash!\n");
-       for (i = 0; i < pidhash_size; i++)
-               INIT_HLIST_HEAD(&pid_hash[i]);
+               PIDTYPE_MAX * pidhash_size * sizeof(struct hlist_head));
+
+       for (i = 0; i < PIDTYPE_MAX; i++) {
+               pid_hash[i] = alloc_bootmem(pidhash_size *
+                                       sizeof(*(pid_hash[i])));
+               if (!pid_hash[i])
+                       panic("Could not alloc pidhash!\n");
+               for (j = 0; j < pidhash_size; j++)
+                       INIT_HLIST_HEAD(&pid_hash[i][j]);
+       }
 }
 
 void __init pidmap_init(void)
 {
+       int i;
+
        pidmap_array->page = (void *)get_zeroed_page(GFP_KERNEL);
-       /* Reserve PID 0. We never call free_pidmap(0) */
        set_bit(0, pidmap_array->page);
        atomic_dec(&pidmap_array->nr_free);
 
-       pid_cachep = kmem_cache_create("pid", sizeof(struct pid),
-                                       __alignof__(struct pid),
-                                       SLAB_PANIC, NULL, NULL);
+       /*
+        * Allocate PID 0, and hash it via all PID types:
+        */
+
+       for (i = 0; i < PIDTYPE_MAX; i++)
+               attach_pid(current, i, 0);
 }