Do it uncontionally, there's a separate peek function with dma_fence_is_signalled() which can be called from atomic context.
v2: Consensus calls for an unconditional might_sleep (Chris, Christian)
Full audit: - dma-fence.h: Uses MAX_SCHEDULE_TIMOUT, good chance this sleeps - dma-resv.c: Timeout always at least 1 - st-dma-fence.c: Save to sleep in testcases - amdgpu_cs.c: Both callers are for variants of the wait ioctl - amdgpu_device.c: Two callers in vram recover code, both right next to mutex_lock. - amdgpu_vm.c: Use in the vm_wait ioctl, next to _reserve/unreserve - remaining functions in amdgpu: All for test_ib implementations for various engines, caller for that looks all safe (debugfs, driver load, reset) - etnaviv: another wait ioctl - habanalabs: another wait ioctl - nouveau_fence.c: hardcoded 15*HZ ... glorious - nouveau_gem.c: hardcoded 2*HZ ... so not even super consistent, but this one does have a WARN_ON :-/ At least this one is only a fallback path for when kmalloc fails. Maybe this should be put onto some worker list instead, instead of a work per unamp ... - i915/selftests: Hardecoded HZ / 4 or HZ / 8 - i915/gt/selftests: Going up the callchain looks safe looking at nearby callers - i915/gt/intel_gt_requests.c. Wrapped in a mutex_lock - i915/gem_i915_gem_wait.c: The i915-version which is called instead for i915 fences already has a might_sleep() annotation, so all good
Cc: Alex Deucher alexander.deucher@amd.com Cc: Lucas Stach l.stach@pengutronix.de Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Ben Skeggs bskeggs@redhat.com Cc: "VMware Graphics" linux-graphics-maintainer@vmware.com Cc: Oded Gabbay oded.gabbay@gmail.com Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-rdma@vger.kernel.org Cc: amd-gfx@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Christian König christian.koenig@amd.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- drivers/dma-buf/dma-fence.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 90edf2b281b0..656e9ac2d028 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -208,6 +208,8 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) if (WARN_ON(timeout < 0)) return -EINVAL;
+ might_sleep(); + trace_dma_fence_wait_start(fence); if (fence->ops->wait) ret = fence->ops->wait(fence, intr, timeout);