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

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Message-Id: <1330955575-26641-20-git-send-email-jslaby@suse.cz>
Date:	Mon,  5 Mar 2012 14:52:06 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	gregkh@...uxfoundation.org
Cc:	alan@...ux.intel.com, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, jirislaby@...il.com,
	Chris Zankel <chris@...kel.net>
Subject: [PATCH 19/68] XTENSA: iss/console, fix potential deadlock

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@...e.cz>
Cc: Chris Zankel <chris@...kel.net>
---
 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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