[PATCH] proc: convert task_sig() to use lock_task_sighand()

lock_task_sighand() can take ->siglock without holding tasklist_lock.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/proc/array.c b/fs/proc/array.c
index c0e5549..279fbf5 100644 (file)
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -244,6 +244,7 @@ static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
 
 static inline char * task_sig(struct task_struct *p, char *buffer)
 {
+       unsigned long flags;
        sigset_t pending, shpending, blocked, ignored, caught;
        int num_threads = 0;
        unsigned long qsize = 0;
@@ -255,10 +256,8 @@ static inline char * task_sig(struct task_struct *p, char *buffer)
        sigemptyset(&ignored);
        sigemptyset(&caught);
 
-       /* Gather all the data with the appropriate locks held */
-       read_lock(&tasklist_lock);
-       if (p->sighand) {
-               spin_lock_irq(&p->sighand->siglock);
+       rcu_read_lock();
+       if (lock_task_sighand(p, &flags)) {
                pending = p->pending.signal;
                shpending = p->signal->shared_pending.signal;
                blocked = p->blocked;
@@ -266,9 +265,9 @@ static inline char * task_sig(struct task_struct *p, char *buffer)
                num_threads = atomic_read(&p->signal->count);
                qsize = atomic_read(&p->user->sigpending);
                qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
-               spin_unlock_irq(&p->sighand->siglock);
+               unlock_task_sighand(p, &flags);
        }
-       read_unlock(&tasklist_lock);
+       rcu_read_unlock();
 
        buffer += sprintf(buffer, "Threads:\t%d\n", num_threads);
        buffer += sprintf(buffer, "SigQ:\t%lu/%lu\n", qsize, qlim);