From 5dd50aaeb1853ee0953b60fa6d1143d95429ae7b Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 5 Nov 2018 17:40:31 +0000 Subject: Make anon_inodes unconditional Make the anon_inodes facility unconditional so that it can be used by core VFS code and pidfd code. Signed-off-by: David Howells Signed-off-by: Al Viro [christian@brauner.io: adapt commit message to mention pidfds] Signed-off-by: Christian Brauner --- drivers/dma-buf/Kconfig | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/dma-buf') diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig index 2e5a0faa2cb1..3fc9c2efc583 100644 --- a/drivers/dma-buf/Kconfig +++ b/drivers/dma-buf/Kconfig @@ -3,7 +3,6 @@ menu "DMABUF options" config SYNC_FILE bool "Explicit Synchronization Framework" default n - select ANON_INODES select DMA_SHARED_BUFFER ---help--- The Sync File Framework adds explicit syncronization via -- cgit v1.2.3 From c36beba6b296b3c05a0f29753b04775e5ae23886 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 8 May 2019 12:24:52 +0100 Subject: drm/i915: Seal races between async GPU cancellation, retirement and signaling Currently there is an underlying assumption that i915_request_unsubmit() is synchronous wrt the GPU -- that is the request is no longer in flight as we remove it. In the near future that may change, and this may upset our signaling as we can process an interrupt for that request while it is no longer in flight. CPU0 CPU1 intel_engine_breadcrumbs_irq (queue request completion) i915_request_cancel_signaling ... ... i915_request_enable_signaling dma_fence_signal Hence in the time it took us to drop the lock to signal the request, a preemption event may have occurred and re-queued the request. In the process, that request would have seen I915_FENCE_FLAG_SIGNAL clear and so reused the rq->signal_link that was in use on CPU0, leading to bad pointer chasing in intel_engine_breadcrumbs_irq. A related issue was that if someone started listening for a signal on a completed but no longer in-flight request, we missed the opportunity to immediately signal that request. Furthermore, as intel_contexts may be immediately released during request retirement, in order to be entirely sure that intel_engine_breadcrumbs_irq may no longer dereference the intel_context (ce->signals and ce->signal_link), we must wait for irq spinlock. In order to prevent the race, we use a bit in the fence.flags to signal the transfer onto the signal list inside intel_engine_breadcrumbs_irq. For simplicity, we use the DMA_FENCE_FLAG_SIGNALED_BIT as it then quickly signals to any outside observer that the fence is indeed signaled. v2: Sketch out potential dma-fence API for manual signaling v3: And the test_and_set_bit() Fixes: 52c0fdb25c7c ("drm/i915: Replace global breadcrumbs with per-context interrupt tracking") Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20190508112452.18942-1-chris@chris-wilson.co.uk (cherry picked from commit 0152b3b3f49b36b0f1a1bf9f0353dc636f41d8f0) Signed-off-by: Joonas Lahtinen --- drivers/dma-buf/dma-fence.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/dma-buf') diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 3aa8733f832a..9bf06042619a 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -29,6 +29,7 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit); EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal); +EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled); static DEFINE_SPINLOCK(dma_fence_stub_lock); static struct dma_fence dma_fence_stub; -- cgit v1.2.3