[PATCH 19/68] XTENSA: iss/console, fix potential deadlock

From: Jiri Slaby
Date: Mon Mar 05 2012 - 08:56:41 EST


If the timer ticks while we are holding the spinlock, the system
deadlocks. It is due to synchronous del_timer.

So to fix that, use spinlocks that properly disable bottom halves.

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
---
arch/xtensa/platforms/iss/console.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/xtensa/platforms/iss/console.c b/arch/xtensa/platforms/iss/console.c
index 01842e4..94ab8ec 100644
--- a/arch/xtensa/platforms/iss/console.c
+++ b/arch/xtensa/platforms/iss/console.c
@@ -91,11 +91,10 @@ static int rs_open(struct tty_struct *tty, struct file * filp)
*/
static void rs_close(struct tty_struct *tty, struct file * filp)
{
- spin_lock(&timer_lock);
+ spin_lock_bh(&timer_lock);
if (tty->count == 1)
- /* this will cause a deadlock if the timer ticks right now */
del_timer_sync(&serial_timer);
- spin_unlock(&timer_lock);
+ spin_unlock_bh(&timer_lock);
}


--
1.7.9.2


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