linux-kernel - [PATCH 1/2] iommu/amd: Make sure iommu->need

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Date:	Mon, 5 Sep 2011 16:57:00 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	<iommu@...ts.linux-foundation.org>
CC:	<linux-kernel@...r.kernel.org>,
	Joerg Roedel <joerg.roedel@....com>, <stable@...nel.org>
Subject: [PATCH 1/2] iommu/amd: Make sure iommu->need_sync contains correct value

The value is only set to true but never set back to false,
which causes to many completion-wait commands to be sent to
hardware. Fix it with this patch.

Cc: stable@...nel.org
Signed-off-by: Joerg Roedel <joerg.roedel@....com>
---
 drivers/iommu/amd_iommu.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index a14f8dc..4565223 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -605,7 +605,9 @@ static void build_inv_all(struct iommu_cmd *cmd)
  * Writes the command to the IOMMUs command buffer and informs the
  * hardware about the new command.
  */
-static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
+static int iommu_queue_command_sync(struct amd_iommu *iommu,
+				    struct iommu_cmd *cmd,
+				    bool sync)
 {
 	u32 left, tail, head, next_tail;
 	unsigned long flags;
@@ -639,13 +641,18 @@ again:
 	copy_cmd_to_buffer(iommu, cmd, tail);
 
 	/* We need to sync now to make sure all commands are processed */
-	iommu->need_sync = true;
+	iommu->need_sync = sync;
 
 	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	return 0;
 }
 
+static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
+{
+	return iommu_queue_command_sync(iommu, cmd, true);
+}
+
 /*
  * This function queues a completion wait command into the command
  * buffer of an IOMMU
@@ -661,7 +668,7 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
 
 	build_completion_wait(&cmd, (u64)&sem);
 
-	ret = iommu_queue_command(iommu, &cmd);
+	ret = iommu_queue_command_sync(iommu, &cmd, false);
 	if (ret)
 		return ret;
 
-- 
1.7.4.1


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