From e58b4dea9054c85688c8f639ebdfc8115261dae2 Mon Sep 17 00:00:00 2001 From: Philipp Stanner Date: Mon, 1 Dec 2025 11:50:05 +0100 Subject: [PATCH] dma-buf/dma-fence: Add dma_fence_test_signaled_flag() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The dma_fence framework checks at many places whether the signaled flag of a fence is already set. The code can be simplified and made more readable by providing a helper function for that. Add dma_fence_test_signaled_flag(), which only checks whether a fence is signaled. Use it internally. Suggested-by: Tvrtko Ursulin Reviewed-by: Christian König Signed-off-by: Philipp Stanner Link: https://patch.msgid.link/20251201105011.19386-3-phasta@kernel.org --- drivers/dma-buf/dma-fence.c | 16 ++++++++-------- include/linux/dma-fence.h | 24 ++++++++++++++++++++++-- 2 files changed, 30 insertions(+), 10 deletions(-) diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 2bb18af369b99..5e96cb5f1f3b1 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -543,7 +543,7 @@ void dma_fence_release(struct kref *kref) trace_dma_fence_destroy(fence); if (!list_empty(&fence->cb_list) && - !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + !dma_fence_test_signaled_flag(fence)) { const char __rcu *timeline; const char __rcu *driver; unsigned long flags; @@ -600,7 +600,7 @@ static bool __dma_fence_enable_signaling(struct dma_fence *fence) was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (dma_fence_test_signaled_flag(fence)) return false; if (!was_set && fence->ops->enable_signaling) { @@ -664,7 +664,7 @@ int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb, if (WARN_ON(!fence || !func)) return -EINVAL; - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + if (dma_fence_test_signaled_flag(fence)) { INIT_LIST_HEAD(&cb->node); return -ENOENT; } @@ -781,7 +781,7 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout) spin_lock_irqsave(fence->lock, flags); - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (dma_fence_test_signaled_flag(fence)) goto out; if (intr && signal_pending(current)) { @@ -798,7 +798,7 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout) cb.task = current; list_add(&cb.base.node, &fence->cb_list); - while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) { + while (!dma_fence_test_signaled_flag(fence) && ret > 0) { if (intr) __set_current_state(TASK_INTERRUPTIBLE); else @@ -830,7 +830,7 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count, for (i = 0; i < count; ++i) { struct dma_fence *fence = fences[i]; - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + if (dma_fence_test_signaled_flag(fence)) { if (idx) *idx = i; return true; @@ -1108,7 +1108,7 @@ const char __rcu *dma_fence_driver_name(struct dma_fence *fence) RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "RCU protection is required for safe access to returned string"); - if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (!dma_fence_test_signaled_flag(fence)) return fence->ops->get_driver_name(fence); else return "detached-driver"; @@ -1140,7 +1140,7 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence) RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "RCU protection is required for safe access to returned string"); - if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (!dma_fence_test_signaled_flag(fence)) return fence->ops->get_driver_name(fence); else return "signaled-timeline"; diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 64639e1041102..19972f5d176f3 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -401,6 +401,26 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence); const char __rcu *dma_fence_driver_name(struct dma_fence *fence); const char __rcu *dma_fence_timeline_name(struct dma_fence *fence); +/* + * dma_fence_test_signaled_flag - Only check whether a fence is signaled yet. + * @fence: the fence to check + * + * This function just checks whether @fence is signaled, without interacting + * with the fence in any way. The user must, therefore, ensure through other + * means that fences get signaled eventually. + * + * This function uses test_bit(), which is thread-safe. Naturally, this function + * should be used opportunistically; a fence could get signaled at any moment + * after the check is done. + * + * Return: true if signaled, false otherwise. + */ +static inline bool +dma_fence_test_signaled_flag(struct dma_fence *fence) +{ + return test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags); +} + /** * dma_fence_is_signaled_locked - Return an indication if the fence * is signaled yet. @@ -418,7 +438,7 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence); static inline bool dma_fence_is_signaled_locked(struct dma_fence *fence) { - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (dma_fence_test_signaled_flag(fence)) return true; if (fence->ops->signaled && fence->ops->signaled(fence)) { @@ -448,7 +468,7 @@ dma_fence_is_signaled_locked(struct dma_fence *fence) static inline bool dma_fence_is_signaled(struct dma_fence *fence) { - if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + if (dma_fence_test_signaled_flag(fence)) return true; if (fence->ops->signaled && fence->ops->signaled(fence)) { -- 2.47.3