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AMD IOMMU: protect completion wait loop with iommu lock 

The unlocked polling of the ComWaitInt bit in the IOMMU completion wait
path is racy. Protect it with the iommu lock.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Joerg Roedel 2008-09-17 14:19:15 +02:00 committed by Ingo Molnar
parent ee2fa7435b
commit 7e4f88da7b
1 changed files with 8 additions and 4 deletions
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12
arch/x86/kernel/amd_iommu.c
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@ -101,10 +101,10 @@ static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
*/
static int iommu_completion_wait(struct amd_iommu *iommu)
{
int ret, ready = 0;
int ret = 0, ready = 0;
unsigned status = 0;
struct iommu_cmd cmd;
unsigned long i = 0;
unsigned long flags, i = 0;
memset(&cmd, 0, sizeof(cmd));
cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
@ -112,10 +112,12 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
iommu->need_sync = 0;
ret = iommu_queue_command(iommu, &cmd);
spin_lock_irqsave(&iommu->lock, flags);
ret = __iommu_queue_command(iommu, &cmd);
if (ret)
return ret;
goto out;
while (!ready && (i < EXIT_LOOP_COUNT)) {
++i;
@ -130,6 +132,8 @@ static int iommu_completion_wait(struct amd_iommu *iommu)
if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");
out:
spin_unlock_irqrestore(&iommu->lock, flags);
return 0;
}