From b022b4a44abda9b6f89777b07e538be6f8f7aacb Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 23 Nov 2012 15:59:43 +0100 Subject: [PATCH] aio: avoid livelock behavior for Win32 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 Signed-off-by: Anthony Liguori --- aio-win32.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/aio-win32.c b/aio-win32.c index a84eb71246..cec4646635 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;