Make dma_fence_enable_sw_signaling() behave like its dma_fence_add_callback() and dma_fence_default_wait() counterparts and perform the test to enable signaling under the fence->lock, along with the action to do so. This ensure that should an implementation be trying to flush the cb_list (by signaling) on retirement before freeing the fence, it can do so in a race-free manner.
See also 0fc89b6802ba ("dma-fence: Simply wrap dma_fence_signal_locked with dma_fence_signal").
v2: Refactor all 3 enable_signaling paths to use a common function.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk --- drivers/dma-buf/dma-fence.c | 78 +++++++++++++++++-------------------- 1 file changed, 35 insertions(+), 43 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 2c136aee3e79..4a1442a93f04 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -273,6 +273,30 @@ void dma_fence_free(struct dma_fence *fence) } EXPORT_SYMBOL(dma_fence_free);
+static bool __dma_fence_enable_signaling(struct dma_fence *fence) +{ + bool was_set; + + lockdep_assert_held(fence->lock); + + was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, + &fence->flags); + + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + return true; + + if (!was_set && fence->ops->enable_signaling) { + if (!fence->ops->enable_signaling(fence)) { + dma_fence_signal_locked(fence); + return true; + } + + trace_dma_fence_enable_signal(fence); + } + + return false; +} + /** * dma_fence_enable_sw_signaling - enable signaling on fence * @fence: the fence to enable @@ -285,19 +309,12 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence) { unsigned long flags;
- if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, - &fence->flags) && - !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && - fence->ops->enable_signaling) { - trace_dma_fence_enable_signal(fence); - - spin_lock_irqsave(fence->lock, flags); - - if (!fence->ops->enable_signaling(fence)) - dma_fence_signal_locked(fence); + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + return;
- spin_unlock_irqrestore(fence->lock, flags); - } + spin_lock_irqsave(fence->lock, flags); + __dma_fence_enable_signaling(fence); + spin_unlock_irqrestore(fence->lock, flags); } EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
@@ -331,7 +348,6 @@ int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb, { unsigned long flags; int ret = 0; - bool was_set;
if (WARN_ON(!fence || !func)) return -EINVAL; @@ -343,25 +359,14 @@ int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
spin_lock_irqsave(fence->lock, flags);
- 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_enable_signaling(fence)) { + INIT_LIST_HEAD(&cb->node); ret = -ENOENT; - else if (!was_set && fence->ops->enable_signaling) { - trace_dma_fence_enable_signal(fence); - - if (!fence->ops->enable_signaling(fence)) { - dma_fence_signal_locked(fence); - ret = -ENOENT; - } - } - - if (!ret) { + } else { cb->func = func; list_add_tail(&cb->node, &fence->cb_list); - } else - INIT_LIST_HEAD(&cb->node); + } + spin_unlock_irqrestore(fence->lock, flags);
return ret; @@ -461,7 +466,6 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout) struct default_wait_cb cb; unsigned long flags; signed long ret = timeout ? timeout : 1; - bool was_set;
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) return ret; @@ -473,21 +477,9 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout) goto out; }
- 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_enable_signaling(fence)) goto out;
- if (!was_set && fence->ops->enable_signaling) { - trace_dma_fence_enable_signal(fence); - - if (!fence->ops->enable_signaling(fence)) { - dma_fence_signal_locked(fence); - goto out; - } - } - if (!timeout) { ret = 0; goto out;