From: Will Deacon Date: Fri, 9 Sep 2016 13:33:59 +0000 (+0100) Subject: iommu/arm-smmu: Disable interrupts whilst holding the cmdq lock X-Git-Tag: v4.14-rc1~2291^2^6^2~23 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8ded2909e2c6c34b70ebb45480f6ce68c64fbddc;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: Will Deacon --- diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index c040e24..5db6931 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -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 */