[PATCH] do_task_stat: don't take tty_mutex

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Depends on
	tty-signal-tty-locking.patch

->signal->tty is protected by ->siglock, no need to take the global tty_mutex.

Signed-off-by: Oleg Nesterov <[email protected]>

--- rc2-mm2/fs/proc/array.c~	2006-10-22 19:28:17.000000000 +0400
+++ rc2-mm2/fs/proc/array.c	2006-10-22 19:45:52.000000000 +0400
@@ -346,20 +346,13 @@ static int do_task_stat(struct task_stru
 	sigemptyset(&sigcatch);
 	cutime = cstime = utime = stime = cputime_zero;
 
-	mutex_lock(&tty_mutex);
 	rcu_read_lock();
 	if (lock_task_sighand(task, &flags)) {
 		struct signal_struct *sig = task->signal;
-		struct tty_struct *tty = sig->tty;
 
-		if (tty) {
-			/*
-			 * sig->tty is not stable, but tty_mutex
-			 * protects us from release_dev(tty)
-			 */
-			barrier();
-			tty_pgrp = tty->pgrp;
-			tty_nr = new_encode_dev(tty_devnum(tty));
+		if (sig->tty) {
+			tty_pgrp = sig->tty->pgrp;
+			tty_nr = new_encode_dev(tty_devnum(sig->tty));
 		}
 
 		num_threads = atomic_read(&sig->count);
@@ -395,7 +388,6 @@ static int do_task_stat(struct task_stru
 		unlock_task_sighand(task, &flags);
 	}
 	rcu_read_unlock();
-	mutex_unlock(&tty_mutex);
 
 	if (!whole || num_threads<2)
 		wchan = get_wchan(task);

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux