[PATCH] do_signal_stop: don't take tasklist_lock
[pandora-kernel.git] / kernel / exit.c
index 8037405..44d6c6e 100644 (file)
 #include <linux/cpuset.h>
 #include <linux/syscalls.h>
 #include <linux/signal.h>
+#include <linux/posix-timers.h>
 #include <linux/cn_proc.h>
 #include <linux/mutex.h>
+#include <linux/futex.h>
+#include <linux/compat.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -52,11 +55,76 @@ static void __unhash_process(struct task_struct *p)
        if (thread_group_leader(p)) {
                detach_pid(p, PIDTYPE_PGID);
                detach_pid(p, PIDTYPE_SID);
-               if (p->pid)
-                       __get_cpu_var(process_counts)--;
+
+               list_del_init(&p->tasks);
+               __get_cpu_var(process_counts)--;
+       }
+
+       remove_parent(p);
+}
+
+/*
+ * This function expects the tasklist_lock write-locked.
+ */
+static void __exit_signal(struct task_struct *tsk)
+{
+       struct signal_struct *sig = tsk->signal;
+       struct sighand_struct *sighand;
+
+       BUG_ON(!sig);
+       BUG_ON(!atomic_read(&sig->count));
+
+       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);
+       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);
+               /*
+                * 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;
+               sig = NULL; /* Marker for below. */
        }
 
-       REMOVE_LINKS(p);
+       __unhash_process(tsk);
+
+       tsk->signal = NULL;
+       cleanup_sighand(tsk);
+       spin_unlock(&sighand->siglock);
+       rcu_read_unlock();
+
+       clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
+       flush_sigqueue(&tsk->pending);
+       if (sig) {
+               flush_sigqueue(&sig->shared_pending);
+               __cleanup_signal(sig);
+       }
 }
 
 void release_task(struct task_struct * p)
@@ -65,21 +133,14 @@ void release_task(struct task_struct * p)
        task_t *leader;
        struct dentry *proc_dentry;
 
-repeat: 
+repeat:
        atomic_dec(&p->user->processes);
        spin_lock(&p->proc_lock);
        proc_dentry = proc_pid_unhash(p);
        write_lock_irq(&tasklist_lock);
-       if (unlikely(p->ptrace))
-               __ptrace_unlink(p);
+       ptrace_unlink(p);
        BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
        __exit_signal(p);
-       /*
-        * Note that the fastpath in sys_times depends on __exit_signal having
-        * updated the counters before a task is removed from the tasklist of
-        * the process by __unhash_process.
-        */
-       __unhash_process(p);
 
        /*
         * If we are the last non-leader member of the thread
@@ -114,21 +175,6 @@ repeat:
                goto repeat;
 }
 
-/* we are using it only for SMP init */
-
-void unhash_process(struct task_struct *p)
-{
-       struct dentry *proc_dentry;
-
-       spin_lock(&p->proc_lock);
-       proc_dentry = proc_pid_unhash(p);
-       write_lock_irq(&tasklist_lock);
-       __unhash_process(p);
-       write_unlock_irq(&tasklist_lock);
-       spin_unlock(&p->proc_lock);
-       proc_pid_flush(proc_dentry);
-}
-
 /*
  * This checks not only the pgrp, but falls back on the pid if no
  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
@@ -236,10 +282,10 @@ static void reparent_to_init(void)
 
        ptrace_unlink(current);
        /* Reparent to init */
-       REMOVE_LINKS(current);
+       remove_parent(current);
        current->parent = child_reaper;
        current->real_parent = child_reaper;
-       SET_LINKS(current);
+       add_parent(current);
 
        /* Set the exit signal to SIGCHLD so we signal init on exit */
        current->exit_signal = SIGCHLD;
@@ -536,13 +582,13 @@ static void exit_mm(struct task_struct * tsk)
        mmput(mm);
 }
 
-static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper)
+static inline void choose_new_parent(task_t *p, task_t *reaper)
 {
        /*
         * Make sure we're not reparenting to ourselves and that
         * the parent is not a zombie.
         */
-       BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE);
+       BUG_ON(p == reaper || reaper->exit_state);
        p->real_parent = reaper;
 }
 
@@ -567,9 +613,9 @@ static void reparent_thread(task_t *p, task_t *father, int traced)
                 * anyway, so let go of it.
                 */
                p->ptrace = 0;
-               list_del_init(&p->sibling);
+               remove_parent(p);
                p->parent = p->real_parent;
-               list_add_tail(&p->sibling, &p->parent->children);
+               add_parent(p);
 
                /* If we'd notified the old parent about this child's death,
                 * also notify the new parent.
@@ -643,7 +689,7 @@ static void forget_original_parent(struct task_struct * father,
 
                if (father == p->real_parent) {
                        /* reparent with a reaper, real father it's us */
-                       choose_new_parent(p, reaper, child_reaper);
+                       choose_new_parent(p, reaper);
                        reparent_thread(p, father, 0);
                } else {
                        /* reparent ptraced task to its real parent */
@@ -664,7 +710,7 @@ static void forget_original_parent(struct task_struct * father,
        }
        list_for_each_safe(_p, _n, &father->ptrace_children) {
                p = list_entry(_p,struct task_struct,ptrace_list);
-               choose_new_parent(p, reaper, child_reaper);
+               choose_new_parent(p, reaper);
                reparent_thread(p, father, 1);
        }
 }
@@ -805,7 +851,7 @@ fastcall NORET_TYPE void do_exit(long code)
                panic("Aiee, killing interrupt handler!");
        if (unlikely(!tsk->pid))
                panic("Attempted to kill the idle task!");
-       if (unlikely(tsk->pid == 1))
+       if (unlikely(tsk == child_reaper))
                panic("Attempted to kill init!");
 
        if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
@@ -852,6 +898,12 @@ fastcall NORET_TYPE void do_exit(long code)
                exit_itimers(tsk->signal);
                acct_process(code);
        }
+       if (unlikely(tsk->robust_list))
+               exit_robust_list(tsk);
+#ifdef CONFIG_COMPAT
+       if (unlikely(tsk->compat_robust_list))
+               compat_exit_robust_list(tsk);
+#endif
        exit_mm(tsk);
 
        exit_sem(tsk);
@@ -1273,7 +1325,7 @@ bail_ref:
 
        /* move to end of parent's list to avoid starvation */
        remove_parent(p);
-       add_parent(p, p->parent);
+       add_parent(p);
 
        write_unlock_irq(&tasklist_lock);