From b598cb2214cbc197a7d8a677644a7ef3ea17c2c1 Mon Sep 17 00:00:00 2001 From: Alexey Kardashevskiy Date: Wed, 18 Jul 2012 22:52:04 +1000 Subject: eventfd: making it thread safe 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 Signed-off-by: Anthony Liguori (cherry picked from commit 55ce75faf253d4369670f60409c608e665e8dde9) Signed-off-by: Michael Roth --- iohandler.c | 1 + 1 file changed, 1 insertion(+) diff --git a/iohandler.c b/iohandler.c index 3c74de612..dea43552d 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; } -- cgit v1.2.3