From 227123de3d862e691131708b7f55260bee17f2b7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Michel=20D=C3=A4nzer?= Date: Mon, 28 Jan 2019 18:24:41 +0100 Subject: Call drmHandleEvent again if it was interrupted by a signal drmHandleEvent can be interrupted by a signal in read(), in which case it doesn't process any events but returns -1, which drm_handle_event propagated to its callers. This could cause the following failure cascade: 1. drm_wait_pending_flip stopped waiting for a pending flip. 2. Its caller cleared drmmode_crtc->flip_pending before the flip completed. 3. Another flip was attempted but got an unexpected EBUSY error because the previous flip was still pending. 4. TearFree was disabled due to the error. The solution is to call drmHandleEvent if it was interrupted by a signal. We can do that in drm_handle_event, because when that is called, either it is known that there are events ready to be processed, or the caller has to wait for events to arrive anyway. Bugzilla: https://bugs.freedesktop.org/109364 (Ported from amdgpu commit 3ff2cc225f6bc08364ee007fa54e9d0150adaf11) --- src/radeon_drm_queue.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/src/radeon_drm_queue.c b/src/radeon_drm_queue.c index d8a8243c..2e2b8404 100644 --- a/src/radeon_drm_queue.c +++ b/src/radeon_drm_queue.c @@ -30,6 +30,8 @@ #include "config.h" #endif +#include + #include #include #include @@ -277,7 +279,20 @@ radeon_drm_handle_event(int fd, drmEventContext *event_context) struct radeon_drm_queue_entry *e; int r; - r = drmHandleEvent(fd, event_context); + /* Retry drmHandleEvent if it was interrupted by a signal in read() */ + do { + r = drmHandleEvent(fd, event_context); + } while (r < 0 && (errno == EINTR || errno == EAGAIN)); + + if (r < 0) { + static Bool printed; + + if (!printed) { + ErrorF("%s: drmHandleEvent returned %d, errno=%d (%s)\n", + __func__, r, errno, strerror(errno)); + printed = TRUE; + } + } while (!xorg_list_is_empty(&radeon_drm_flip_signalled)) { e = xorg_list_first_entry(&radeon_drm_flip_signalled, -- cgit v1.2.3