From eced8058c82a3a81ae480a6546e2da32100dddfa Mon Sep 17 00:00:00 2001 From: Pranjal Shrivastava Date: Tue, 28 Jul 2026 21:11:23 +0000 Subject: [PATCH] iommu/arm-smmu-v3: Convert to use atomic poll timeout The arm_smmu_write_reg_sync() helper is currently implemented using readl_relaxed_poll_timeout() (that relies on usleep_range() internally) which becomes a critical issue when used in the gerror irq handler. If the SMMU hits a gerror and enters Service Failure Mode (GERROR_SFM_ERR), the gerror handler calls arm_smmu_device_disable() in hard-irq context. This becomes a problem as arm_smmu_device_disable() inevitably calls arm_smmu_write_reg_sync() which might attempt to sleep inside a hard-irq context. Fix this by converting the arm_smmu_write_reg_sync to use the readl_relaxed_poll_timeout_atomic() polling helper. (Discovered while running Sashiko locally on another patch series). Reported-by: Sashiko Fixes: 48ec83bcbcf5 ("iommu/arm-smmu: Add initial driver support for ARM SMMUv3 devices") Signed-off-by: Pranjal Shrivastava Signed-off-by: Will Deacon --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 267dfc40919c..de5fba0b6d09 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -4618,8 +4618,9 @@ static int arm_smmu_write_reg_sync(struct arm_smmu_device *smmu, u32 val, u32 reg; writel_relaxed(val, smmu->base + reg_off); - return readl_relaxed_poll_timeout(smmu->base + ack_off, reg, reg == val, - 1, ARM_SMMU_POLL_TIMEOUT_US); + return readl_relaxed_poll_timeout_atomic(smmu->base + ack_off, reg, + reg == val, 1, + ARM_SMMU_POLL_TIMEOUT_US); } /* GBPA is "special" */