linux-kernel - [PATCH 4.0 003/148] iommu/amd: Fix bug in put_pasid_state

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Message-Id: <20150603114205.476704048@linuxfoundation.org>
Date:	Wed,  3 Jun 2015 21:07:53 +0900
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Oded Gabbay <oded.gabbay@....com>,
	Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 4.0 003/148] iommu/amd: Fix bug in put_pasid_state_wait

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oded Gabbay <oded.gabbay@....com>

commit 1bf1b431d98d7e5b5419876d4c219469e60693e1 upstream.

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@....com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iommu/amd_iommu_v2.c |    1 +
 1 file changed, 1 insertion(+)

--- 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
 
 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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