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Subject[PATCH 1/3] 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>

--- rc6-mm1/fs/proc/array.c~1_sig 2006-09-09 16:49:09.000000000 +0400
+++ rc6-mm1/fs/proc/array.c 2006-09-09 17:47:22.000000000 +0400
@@ -244,6 +244,7 @@ static void collect_sigign_sigcatch(stru

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 tas
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 tas
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);
-
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