From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60450) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y9Gzz-0004AU-89 for qemu-devel@nongnu.org; Thu, 08 Jan 2015 12:36:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Y9Gzl-0006jM-4e for qemu-devel@nongnu.org; Thu, 08 Jan 2015 12:35:55 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:53173) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Y9Gzk-0006if-CD for qemu-devel@nongnu.org; Thu, 08 Jan 2015 12:35:41 -0500 Received: from /spool/local by e38.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 8 Jan 2015 10:35:39 -0700 From: Michael Roth Date: Thu, 8 Jan 2015 11:33:53 -0600 Message-Id: <1420738472-23267-50-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1420738472-23267-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1420738472-23267-1-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 49/88] Make qemu_shutdown_requested signal-safe List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org From: Jan Kiszka qemu_shutdown_requested may be interrupted by qemu_system_killed. If the latter sets shutdown_requested after qemu_shutdown_requested has read it but before it was cleared, the shutdown event is lost. Fix this by using atomic_xchg. This provides a different fix for the problem which commit 15124e142 attempts to deal with. That commit breaks use of ^C to drop into gdb, and so this approach is better (and 15124e142 can be reverted). Signed-off-by: Jan Kiszka Reviewed-by: Gonglei Reviewed-by: Paolo Bonzini [PMM: commit message tweak] Signed-off-by: Peter Maydell (cherry picked from commit 817ef04db2cfa2df04daffd6917f4ea7605f6403) Signed-off-by: Michael Roth --- vl.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/vl.c b/vl.c index 7f8bd39..3650f4f 100644 --- a/vl.c +++ b/vl.c @@ -1745,9 +1745,7 @@ int qemu_reset_requested_get(void) static int qemu_shutdown_requested(void) { - int r = shutdown_requested; - shutdown_requested = 0; - return r; + return atomic_xchg(&shutdown_requested, 0); } static void qemu_kill_report(void) -- 1.9.1