[PATCH] disassociate_ctty SMP fix

Rik van Riel (riel@conectiva.com.br)
Sat, 11 Jan 2003 11:41:41 -0200 (BRST)


Hi,

the following patch, against today's BK tree, fixes a small
SMP race in disassociate_ctty. This function gets called
from do_exit, without the BKL held.

However, it sets the *tty variable before grabbing the bkl,
then makes decisions on what the variable was set to before
the lock was grabbed, despite the fact that another process
could modify its ->tty pointer in this same function.

please apply

Rik

-- 
Bravely reimplemented by the knights who say "NIH".
http://www.surriel.com/		http://guru.conectiva.com/
Current spamtrap:  <a href=mailto:"october@surriel.com">october@surriel.com</a>

===== drivers/char/tty_io.c 1.50 vs edited ===== --- 1.50/drivers/char/tty_io.c Sat Dec 7 16:23:16 2002 +++ edited/drivers/char/tty_io.c Sat Jan 11 11:37:34 2003 @@ -577,7 +577,7 @@ */ void disassociate_ctty(int on_exit) { - struct tty_struct *tty = current->tty; + struct tty_struct *tty; struct task_struct *p; struct list_head *l; struct pid *pid; @@ -585,6 +585,7 @@

lock_kernel();

+ tty = current->tty; if (tty) { tty_pgrp = tty->pgrp; if (on_exit && tty->driver.type != TTY_DRIVER_TYPE_PTY) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/