[PATCH v2] iommu/arm-smmu: avoid calling request_irq in atomic context

[Mitchel Humpherys]

request_irq shouldn't be called from atomic context since it might
sleep, but we're calling it with a spinlock held, resulting in:

    [    9.172202] BUG: sleeping function called from invalid context at kernel/mm/slub.c:926
    [    9.182989] in_atomic(): 1, irqs_disabled(): 128, pid: 1, name: swapper/0
    [    9.189762] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W    3.10.40-gbc1b510b-38437-g55831d3bd9-dirty #97
    [    9.199757] [<c020c448>] (unwind_backtrace+0x0/0x11c) from [<c02097d0>] (show_stack+0x10/0x14)
    [    9.208346] [<c02097d0>] (show_stack+0x10/0x14) from [<c0301d74>] (kmem_cache_alloc_trace+0x3c/0x210)
    [    9.217543] [<c0301d74>] (kmem_cache_alloc_trace+0x3c/0x210) from [<c0276a48>] (request_threaded_irq+0x88/0x11c)
    [    9.227702] [<c0276a48>] (request_threaded_irq+0x88/0x11c) from [<c0931ca4>] (arm_smmu_attach_dev+0x188/0x858)
    [    9.237686] [<c0931ca4>] (arm_smmu_attach_dev+0x188/0x858) from [<c0212cd8>] (arm_iommu_attach_device+0x18/0xd0)
    [    9.247837] [<c0212cd8>] (arm_iommu_attach_device+0x18/0xd0) from [<c093314c>] (arm_smmu_test_probe+0x68/0xd4)
    [    9.257823] [<c093314c>] (arm_smmu_test_probe+0x68/0xd4) from [<c05aadd0>] (driver_probe_device+0x12c/0x330)
    [    9.267629] [<c05aadd0>] (driver_probe_device+0x12c/0x330) from [<c05ab080>] (__driver_attach+0x68/0x8c)
    [    9.277090] [<c05ab080>] (__driver_attach+0x68/0x8c) from [<c05a92d4>] (bus_for_each_dev+0x70/0x84)
    [    9.286118] [<c05a92d4>] (bus_for_each_dev+0x70/0x84) from [<c05aa3b0>] (bus_add_driver+0x100/0x244)
    [    9.295233] [<c05aa3b0>] (bus_add_driver+0x100/0x244) from [<c05ab5d0>] (driver_register+0x9c/0x124)
    [    9.304347] [<c05ab5d0>] (driver_register+0x9c/0x124) from [<c0933088>] (arm_smmu_test_init+0x14/0x38)
    [    9.313635] [<c0933088>] (arm_smmu_test_init+0x14/0x38) from [<c0200618>] (do_one_initcall+0xb8/0x160)
    [    9.322926] [<c0200618>] (do_one_initcall+0xb8/0x160) from [<c1200b7c>] (kernel_init_freeable+0x108/0x1cc)
    [    9.332564] [<c1200b7c>] (kernel_init_freeable+0x108/0x1cc) from [<c0b924b0>] (kernel_init+0xc/0xe4)
    [    9.341675] [<c0b924b0>] (kernel_init+0xc/0xe4) from [<c0205e38>] (ret_from_fork+0x14/0x3c)

Fix this by moving the request_irq out of the critical section. This
should be okay since smmu_domain->smmu is still being protected by the
critical section. Also, we still don't program the Stream Match Register
until after registering our interrupt handler so we shouldn't be missing
any interrupts.

Signed-off-by: Mitchel Humpherys <mitchelh at codeaurora.org>
---
Changelog:

  - v2: return error code from request_irq on failure
---
 drivers/iommu/arm-smmu.c | 37 +++++++++++++++++--------------------
 1 file changed, 17 insertions(+), 20 deletions(-)
---
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index f3f66416e2..8e17f8d2e4 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -868,7 +868,7 @@ static void arm_smmu_init_context_bank(struct arm_smmu_domain *smmu_domain)
 static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 					struct arm_smmu_device *smmu)
 {
-	int irq, ret, start;
+	int ret, start;
 	struct arm_smmu_domain *smmu_domain = domain->priv;
 	struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
 
@@ -900,23 +900,9 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 		cfg->irptndx = cfg->cbndx;
 	}
 
-	irq = smmu->irqs[smmu->num_global_irqs + cfg->irptndx];
-	ret = request_irq(irq, arm_smmu_context_fault, IRQF_SHARED,
-			  "arm-smmu-context-fault", domain);
-	if (IS_ERR_VALUE(ret)) {
-		dev_err(smmu->dev, "failed to request context IRQ %d (%u)\n",
-			cfg->irptndx, irq);
-		cfg->irptndx = INVALID_IRPTNDX;
-		goto out_free_context;
-	}
-
 	smmu_domain->smmu = smmu;
 	arm_smmu_init_context_bank(smmu_domain);
 	return 0;
-
-out_free_context:
-	__arm_smmu_free_bitmap(smmu->context_map, cfg->cbndx);
-	return ret;
 }
 
 static void arm_smmu_destroy_domain_context(struct iommu_domain *domain)
@@ -1172,10 +1158,11 @@ static void arm_smmu_domain_remove_master(struct arm_smmu_domain *smmu_domain,
 
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
-	int ret = -EINVAL;
+	int irq, ret = -EINVAL;
 	struct arm_smmu_domain *smmu_domain = domain->priv;
 	struct arm_smmu_device *smmu;
-	struct arm_smmu_master_cfg *cfg;
+	struct arm_smmu_master_cfg *master_cfg;
+	struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
 	unsigned long flags;
 
 	smmu = dev_get_master_dev(dev)->archdata.iommu;
@@ -1203,12 +1190,22 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	}
 	spin_unlock_irqrestore(&smmu_domain->lock, flags);
 
+	irq = smmu->irqs[smmu->num_global_irqs + cfg->irptndx];
+	ret = request_irq(irq, arm_smmu_context_fault, IRQF_SHARED,
+			  "arm-smmu-context-fault", domain);
+	if (IS_ERR_VALUE(ret)) {
+		dev_err(smmu->dev, "failed to request context IRQ %d (%u)\n",
+			cfg->irptndx, irq);
+		cfg->irptndx = INVALID_IRPTNDX;
+		return ret;
+	}
+
 	/* Looks ok, so add the device to the domain */
-	cfg = find_smmu_master_cfg(smmu_domain->smmu, dev);
-	if (!cfg)
+	master_cfg = find_smmu_master_cfg(smmu_domain->smmu, dev);
+	if (!master_cfg)
 		return -ENODEV;
 
-	return arm_smmu_domain_add_master(smmu_domain, cfg);
+	return arm_smmu_domain_add_master(smmu_domain, master_cfg);
 
 err_unlock:
 	spin_unlock_irqrestore(&smmu_domain->lock, flags);
-- 
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