-----Original Message----- From: Intel-gfx [mailto:intel-gfx-bounces@lists.freedesktop.org] On Behalf Of Chris Wilson Sent: Thursday, October 3, 2019 9:24 AM To: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Subject: [Intel-gfx] [PATCH v3] dma-fence: Serialise signal enabling (dma_fence_enable_sw_signaling)
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
Return false for "could not _enable_ signaling as it was already signaled"
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..b58528c1cc9d 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);
With this held...
- 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 false;
Would making these the non-atomic versions be useful (and/or reasonable)?
Mike
- if (!was_set && fence->ops->enable_signaling) {
if (!fence->ops->enable_signaling(fence)) {dma_fence_signal_locked(fence);return false;}trace_dma_fence_enable_signal(fence);- }
- return true;
+}
/**
- 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))
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) {
- if (__dma_fence_enable_signaling(fence)) { cb->func = func; list_add_tail(&cb->node, &fence->cb_list);
- } else
} else { INIT_LIST_HEAD(&cb->node);
ret = -ENOENT;}
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;
-- 2.23.0
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