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iommu/arm-smmu: Disable interrupts whilst holding the cmdq lock 

The cmdq lock is taken whenever we issue commands into the command queue,
which can occur in IRQ context (as a result of unmap) or in process
context (as a result of a threaded IRQ handler or device probe).

This can lead to a theoretical deadlock if the interrupt handler
performing the unmap hits whilst the lock is taken, so explicitly use
the {irqsave,irqrestore} spin_lock accessors for the cmdq lock.

Tested-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
hifive-unleashed-5.1
Will Deacon 2016-09-09 14:33:59 +01:00
parent bcfced1580
commit 8ded2909e2
1 changed files with 3 additions and 2 deletions
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5
drivers/iommu/arm-smmu-v3.c
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@ -893,6 +893,7 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
struct arm_smmu_cmdq_ent *ent)
{
u64 cmd[CMDQ_ENT_DWORDS];
unsigned long flags;
bool wfe = !!(smmu->features & ARM_SMMU_FEAT_SEV);
struct arm_smmu_queue *q = &smmu->cmdq.q;
@ -902,7 +903,7 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
return;
}
spin_lock(&smmu->cmdq.lock);
spin_lock_irqsave(&smmu->cmdq.lock, flags);
while (queue_insert_raw(q, cmd) == -ENOSPC) {
if (queue_poll_cons(q, false, wfe))
dev_err_ratelimited(smmu->dev, "CMDQ timeout\n");
@ -910,7 +911,7 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
if (ent->opcode == CMDQ_OP_CMD_SYNC && queue_poll_cons(q, true, wfe))
dev_err_ratelimited(smmu->dev, "CMD_SYNC timeout\n");
spin_unlock(&smmu->cmdq.lock);
spin_unlock_irqrestore(&smmu->cmdq.lock, flags);
}
/* Context descriptor manipulation functions */