Re: [PATCH] iommu/amd: Fix bug in put_pasid_state_wait

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Hi Joerg,
Could you please take a look at this patch ?
I want it to be included in stable asap so Fedora 22 will pick it up.

Thanks,
	Oded

On 04/16/2015 05:08 PM, Oded Gabbay wrote:
This patch fixes a bug in put_pasid_state_wait that appeared in kernel 4.0
The bug is that pasid_state->count wasn't decremented before entering the
wait_event. Thus, the condition in wait_event will never be true.

The fix is to decrement (atomically) the pasid_state->count before the
wait_event.

Signed-off-by: Oded Gabbay <oded.gabbay@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
  drivers/iommu/amd_iommu_v2.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 6d5a5c4..173e70d 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -266,6 +266,7 @@ static void put_pasid_state(struct pasid_state *pasid_state)

  static void put_pasid_state_wait(struct pasid_state *pasid_state)
  {
+	atomic_dec(&pasid_state->count);
  	wait_event(pasid_state->wq, !atomic_read(&pasid_state->count));
  	free_pasid_state(pasid_state);
  }

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