4.6-stable review patch. If anyone has any objections, please let me know.
------------------ From: Maarten Lankhorst <[email protected]> commit 81e257e964268d050f8e9188becd44d50f241d72 upstream. Atomic updates may acquire more state than initially locked through drm_modeset_lock_crtc, running with heavy stress can cause a WARN_ON(crtc->acquire_ctx) in drm_modeset_lock_crtc: [ 601.491296] ------------[ cut here ]------------ [ 601.491366] WARNING: CPU: 0 PID: 2411 at drivers/gpu/drm/drm_modeset_lock.c:191 drm_modeset_lock_crtc+0xeb/0xf0 [drm] [ 601.491369] Modules linked in: drm i915 drm_kms_helper [ 601.491414] CPU: 0 PID: 2411 Comm: kms_cursor_lega Tainted: G U 4.7.0-rc4-patser+ #4798 [ 601.491417] Hardware name: Intel Corporation Skylake Client [ 601.491420] 0000000000000000 ffff88044d153c98 ffffffff812ead28 0000000000000000 [ 601.491425] 0000000000000000 ffff88044d153cd8 ffffffff810868e6 000000bf58058030 [ 601.491431] ffff880088b415e8 ffff880458058030 ffff88008a271548 ffff88008a271568 [ 601.491436] Call Trace: [ 601.491443] [<ffffffff812ead28>] dump_stack+0x4d/0x65 [ 601.491447] [<ffffffff810868e6>] __warn+0xc6/0xe0 [ 601.491452] [<ffffffff81086968>] warn_slowpath_null+0x18/0x20 [ 601.491472] [<ffffffffc00d4ffb>] drm_modeset_lock_crtc+0xeb/0xf0 [drm] [ 601.491491] [<ffffffffc00c5526>] drm_mode_cursor_common+0x66/0x180 [drm] [ 601.491509] [<ffffffffc00c91cc>] drm_mode_cursor_ioctl+0x3c/0x40 [drm] [ 601.491524] [<ffffffffc00bc94d>] drm_ioctl+0x14d/0x530 [drm] [ 601.491540] [<ffffffffc00c9190>] ? drm_mode_setcrtc+0x520/0x520 [drm] [ 601.491545] [<ffffffff81176aeb>] ? handle_mm_fault+0x106b/0x1430 [ 601.491550] [<ffffffff81108441>] ? stop_one_cpu+0x61/0x70 [ 601.491556] [<ffffffff811bb71d>] do_vfs_ioctl+0x8d/0x570 [ 601.491560] [<ffffffff81290d7e>] ? security_file_ioctl+0x3e/0x60 [ 601.491565] [<ffffffff811bbc74>] SyS_ioctl+0x74/0x80 [ 601.491571] [<ffffffff810e321c>] ? posix_get_monotonic_raw+0xc/0x10 [ 601.491576] [<ffffffff8175b11b>] entry_SYSCALL_64_fastpath+0x13/0x8f [ 601.491581] ---[ end trace 56f3d3d85f000d00 ]--- For good measure, test mode_config.acquire_ctx too, although this should never happen. Testcase: kms_cursor_legacy Signed-off-by: Maarten Lankhorst <[email protected]> Reviewed-by: Daniel Vetter <[email protected]> Signed-off-by: Dave Airlie <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/gpu/drm/drm_atomic.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -1288,14 +1288,39 @@ EXPORT_SYMBOL(drm_atomic_add_affected_pl */ void drm_atomic_legacy_backoff(struct drm_atomic_state *state) { + struct drm_device *dev = state->dev; + unsigned crtc_mask = 0; + struct drm_crtc *crtc; int ret; + bool global = false; + + drm_for_each_crtc(crtc, dev) { + if (crtc->acquire_ctx != state->acquire_ctx) + continue; + + crtc_mask |= drm_crtc_mask(crtc); + crtc->acquire_ctx = NULL; + } + + if (WARN_ON(dev->mode_config.acquire_ctx == state->acquire_ctx)) { + global = true; + + dev->mode_config.acquire_ctx = NULL; + } retry: drm_modeset_backoff(state->acquire_ctx); - ret = drm_modeset_lock_all_ctx(state->dev, state->acquire_ctx); + ret = drm_modeset_lock_all_ctx(dev, state->acquire_ctx); if (ret) goto retry; + + drm_for_each_crtc(crtc, dev) + if (drm_crtc_mask(crtc) & crtc_mask) + crtc->acquire_ctx = state->acquire_ctx; + + if (global) + dev->mode_config.acquire_ctx = state->acquire_ctx; } EXPORT_SYMBOL(drm_atomic_legacy_backoff);
