7.1-stable review patch. If anyone has any objections, please let me know.
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From: Tvrtko Ursulin tvrtko.ursulin@igalia.com
[ Upstream commit e94b9f01543cc6a83538c2c2cc645a424d3015ca ]
Trace_dma_fence_signaled, trace_dma_fence_wait_end and trace_dma_fence_destroy can all currently dereference a null fence->ops pointer after it has been reset on fence signalling.
Lets use the safe string getters for most tracepoints to avoid this class of a problem, while for the signal tracepoint we move it to before ops are cleared to avoid losing the driver and timeline name information. Apart from moving it we also need to add a new tracepoint class to bypass the safe name getters since the signaled bit is already set.
For dma_fence_init we also need to use the new tracepoint class since the rcu read lock is not held there, and we can do the same for the enable signaling since there we are certain the fence cannot be signaled while we are holding the lock and have even validated the fence->ops.
Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@igalia.com Fixes: 541c8f2468b9 ("dma-buf: detach fence ops on signal v3") Cc: Christian König christian.koenig@amd.com Cc: Philipp Stanner phasta@kernel.org Cc: Boris Brezillon boris.brezillon@collabora.com Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Christian König christian.koenig@amd.com Signed-off-by: Tvrtko Ursulin tursulin@ursulin.net Link: https://lore.kernel.org/r/20260415083207.40513-2-tvrtko.ursulin@igalia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma-buf/dma-fence.c | 3 ++- include/trace/events/dma_fence.h | 40 +++++++++++++++++++++++++++----- 2 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index a2aa82f4eedd49..b3bfa6943a8e13 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -363,6 +363,8 @@ void dma_fence_signal_timestamp_locked(struct dma_fence *fence, &fence->flags))) return;
+ trace_dma_fence_signaled(fence); + /* * When neither a release nor a wait operation is specified set the ops * pointer to NULL to allow the fence structure to become independent @@ -377,7 +379,6 @@ void dma_fence_signal_timestamp_locked(struct dma_fence *fence,
fence->timestamp = timestamp; set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); - trace_dma_fence_signaled(fence);
list_for_each_entry_safe(cur, tmp, &cb_list, node) { INIT_LIST_HEAD(&cur->node); diff --git a/include/trace/events/dma_fence.h b/include/trace/events/dma_fence.h index 3abba45c0601a4..5b10a9e06fb4ec 100644 --- a/include/trace/events/dma_fence.h +++ b/include/trace/events/dma_fence.h @@ -9,12 +9,40 @@
struct dma_fence;
+DECLARE_EVENT_CLASS(dma_fence, + + TP_PROTO(struct dma_fence *fence), + + TP_ARGS(fence), + + TP_STRUCT__entry( + __string(driver, dma_fence_driver_name(fence)) + __string(timeline, dma_fence_timeline_name(fence)) + __field(unsigned int, context) + __field(unsigned int, seqno) + ), + + TP_fast_assign( + __assign_str(driver); + __assign_str(timeline); + __entry->context = fence->context; + __entry->seqno = fence->seqno; + ), + + TP_printk("driver=%s timeline=%s context=%u seqno=%u", + __get_str(driver), __get_str(timeline), __entry->context, + __entry->seqno) +); + /* * Safe only for call sites which are guaranteed to not race with fence - * signaling,holding the fence->lock and having checked for not signaled, or the - * signaling path itself. + * signaling, holding the fence->lock and having checked for not signaled, or + * the signaling path itself. + * + * TODO: Remove the need for this event class when drivers switch to independent + * fences. */ -DECLARE_EVENT_CLASS(dma_fence, +DECLARE_EVENT_CLASS(dma_fence_ops,
TP_PROTO(struct dma_fence *fence),
@@ -46,7 +74,7 @@ DEFINE_EVENT(dma_fence, dma_fence_emit, TP_ARGS(fence) );
-DEFINE_EVENT(dma_fence, dma_fence_init, +DEFINE_EVENT(dma_fence_ops, dma_fence_init,
TP_PROTO(struct dma_fence *fence),
@@ -60,14 +88,14 @@ DEFINE_EVENT(dma_fence, dma_fence_destroy, TP_ARGS(fence) );
-DEFINE_EVENT(dma_fence, dma_fence_enable_signal, +DEFINE_EVENT(dma_fence_ops, dma_fence_enable_signal,
TP_PROTO(struct dma_fence *fence),
TP_ARGS(fence) );
-DEFINE_EVENT(dma_fence, dma_fence_signaled, +DEFINE_EVENT(dma_fence_ops, dma_fence_signaled,
TP_PROTO(struct dma_fence *fence),