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[Qemu-devel] [PATCH 1.3] aio: avoid livelock behavior for Win32
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 1.3] aio: avoid livelock behavior for Win32 |
Date: |
Fri, 23 Nov 2012 15:59:43 +0100 |
The repeated calls to WaitForMultipleObjects may cause a livelock in aio_poll,
where no progress is made on bottom halves. This patch matches the behavior
of the POSIX code.
Signed-off-by: Paolo Bonzini <address@hidden>
---
Found by the new unit tests.
aio-win32.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/aio-win32.c b/aio-win32.c
index a84eb71..cec4646 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -173,7 +173,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
}
/* wait until next event */
- for (;;) {
+ while (count > 0) {
int timeout = blocking ? INFINITE : 0;
int ret = WaitForMultipleObjects(count, events, FALSE, timeout);
@@ -209,6 +209,9 @@ bool aio_poll(AioContext *ctx, bool blocking)
g_free(tmp);
}
}
+
+ /* Try again, but only call each handler once. */
+ events[ret - WAIT_OBJECT_0] = events[--count];
}
return progress;
--
1.8.0
- [Qemu-devel] [PATCH 1.3] aio: avoid livelock behavior for Win32,
Paolo Bonzini <=