On 15/09/2019 19:45, Chris Wilson wrote:
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").
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
drivers/dma-buf/dma-fence.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 2c136aee3e79..587727089134 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -285,19 +285,18 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence) { unsigned long flags;
- if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return;- spin_lock_irqsave(fence->lock, flags); if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
I dare not to ask if this couldn't be the non-atomic version, but I have empirically proven to myself things are not that straightforward around here.
&fence->flags) &&
!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && fence->ops->enable_signaling) {spin_lock_irqsave(fence->lock, flags);- if (!fence->ops->enable_signaling(fence)) dma_fence_signal_locked(fence);
spin_unlock_irqrestore(fence->lock, flags);
- spin_unlock_irqrestore(fence->lock, flags); } EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com
Regards,
Tvrtko