[Qemu-devel] [PATCH] Make qemu_shutdown_requested signal-safe

[Jan Kiszka <jan.kiszka@web.de>]

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From: Jan Kiszka <jan.kiszka@siemens.com>

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.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 vl.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/vl.c b/vl.c
index 2f81384..f6b3546 100644
--- a/vl.c
+++ b/vl.c
@@ -1609,9 +1609,7 @@ 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)
-- 
1.8.4.5


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