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dma-fence: Serialise signal enabling (dma_fence_enable_sw_signaling)

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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 0fc89b6802 ("dma-fence: Simply wrap dma_fence_signal_locked
with dma_fence_signal").

v2: Refactor all 3 enable_signaling paths to use a common function.
v3: Don't argue, just keep the tracepoint in the existing spot.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004101140.32713-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-10-04 11:11:40 +01:00
parent bebf00512c
commit 9c98f021e4
1 changed files with 35 additions and 43 deletions
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78
drivers/dma-buf/dma-fence.c
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@ -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 false;
if (!was_set && fence->ops->enable_signaling) {
trace_dma_fence_enable_signal(fence);
if (!fence->ops->enable_signaling(fence)) {
dma_fence_signal_locked(fence);
return false;
}
}
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);
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return;
spin_lock_irqsave(fence->lock, flags);
if (!fence->ops->enable_signaling(fence))
dma_fence_signal_locked(fence);
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;