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Commit 88531f72 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[PATCH] do_sigaction: don't take tasklist_lock 



do_sigaction() does not need tasklist_lock anymore, we can simplify the code.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent aacc9094

kernel/signal.c

+3 −19
Original line number Diff line number Diff line
@@ -2301,8 +2301,7 @@ sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo) 
	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;
@@ -2328,6 +2327,7 @@ do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 
	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
@@ -2340,19 +2340,8 @@ do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 
		 *   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))) {

			/*

			 * 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.

			 */

		   (act->sa.sa_handler == SIG_DFL && sig_kernel_ignore(sig))) {

			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);
@@ -2361,12 +2350,7 @@ do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) 
				recalc_sigpending_tsk(t);

				t = next_thread(t);

			} while (t != current);

			spin_unlock_irq(&current->sighand->siglock);

			read_unlock(&tasklist_lock);

			return 0;

		}



		*k = *act;

	}



	spin_unlock_irq(&current->sighand->siglock);