From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:55813) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SrTjp-0002aX-Hy for qemu-devel@nongnu.org; Wed, 18 Jul 2012 08:52:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SrTjg-00061u-3C for qemu-devel@nongnu.org; Wed, 18 Jul 2012 08:52:21 -0400 Received: from mail-yx0-f173.google.com ([209.85.213.173]:45710) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SrTjf-00061q-VL for qemu-devel@nongnu.org; Wed, 18 Jul 2012 08:52:12 -0400 Received: by yenl1 with SMTP id l1so1582885yen.4 for ; Wed, 18 Jul 2012 05:52:11 -0700 (PDT) From: Alexey Kardashevskiy Date: Wed, 18 Jul 2012 22:52:04 +1000 Message-Id: <1342615924-20925-1-git-send-email-aik@ozlabs.ru> In-Reply-To: <1342613333-20239-1-git-send-email-aik@ozlabs.ru> References: <1342613333-20239-1-git-send-email-aik@ozlabs.ru> Subject: [Qemu-devel] [PATCH] eventfd: making it thread safe List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S . Tsirkin" Cc: Alexey Kardashevskiy , qemu-devel@nongnu.org QEMU uses IO handlers to run select() in the main loop. The handlers list is managed by qemu_set_fd_handler() helper which works fine when called from the main thread as it is called when select() is not waiting. However IO handlers list can be changed in the thread other than the main one doing os_host_main_loop_wait(), for example, as a result of a hypercall which changes PCI config space (VFIO on POWER is the case) and enables/disabled MSI/MSIX which closes/creates eventfd handles. As the main loop should be waiting on the newly created eventfds, it has to be restarted. The patch adds the qemu_notify_event() call to interrupt select() to make main_loop() restart select() with the updated IO handlers list. Signed-off-by: Alexey Kardashevskiy Reviewed-by: Paolo Bonzini --- iohandler.c | 1 + 1 file changed, 1 insertion(+) diff --git a/iohandler.c b/iohandler.c index 3c74de6..dea4355 100644 --- a/iohandler.c +++ b/iohandler.c @@ -77,6 +77,7 @@ int qemu_set_fd_handler2(int fd, ioh->fd_write = fd_write; ioh->opaque = opaque; ioh->deleted = 0; + qemu_notify_event(); } return 0; } -- 1.7.10.4