[PATCH v2] iommu/ipmmu-vmsa: Fix allocation in atomic context

[Geert Uytterhoeven]

When attaching a device to an IOMMU group with
CONFIG_DEBUG_ATOMIC_SLEEP=y:

    BUG: sleeping function called from invalid context at mm/slab.h:421
    in_atomic(): 1, irqs_disabled(): 128, pid: 61, name: kworker/1:1
    ...
    Call trace:
     ...
     arm_lpae_alloc_pgtable+0x114/0x184
     arm_64_lpae_alloc_pgtable_s1+0x2c/0x128
     arm_32_lpae_alloc_pgtable_s1+0x40/0x6c
     alloc_io_pgtable_ops+0x60/0x88
     ipmmu_attach_device+0x140/0x334

ipmmu_attach_device() takes a spinlock, while arm_lpae_alloc_pgtable()
allocates memory using GFP_KERNEL.  Originally, the ipmmu-vmsa driver
had its own custom page table allocation implementation using
GFP_ATOMIC, hence the spinlock was fine.

Fix this by replacing the spinlock by a mutex, like the arm-smmu driver
does.

Fixes: f20ed39f53145e45 ("iommu/ipmmu-vmsa: Use the ARM LPAE page table 
allocator")
Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
---
v2:
  - Add Reviewed-by.
---
 drivers/iommu/ipmmu-vmsa.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 40ae6e87cb880223..ef566b4989d6e2f8 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -73,7 +73,7 @@ struct ipmmu_vmsa_domain {
        struct io_pgtable_ops *iop;
 
        unsigned int context_id;
-       spinlock_t lock;                        /* Protects mappings */
+       struct mutex mutex;                     /* Protects mappings */
 };
 
 static struct ipmmu_vmsa_domain *to_vmsa_domain(struct iommu_domain *dom)
@@ -595,7 +595,7 @@ static struct iommu_domain *__ipmmu_domain_alloc(unsigned 
type)
        if (!domain)
                return NULL;
 
-       spin_lock_init(&domain->lock);
+       mutex_init(&domain->mutex);
 
        return &domain->io_domain;
 }
@@ -641,7 +641,6 @@ static int ipmmu_attach_device(struct iommu_domain 
*io_domain,
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;
        struct ipmmu_vmsa_device *mmu = to_ipmmu(dev);
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);
-       unsigned long flags;
        unsigned int i;
        int ret = 0;
 
@@ -650,7 +649,7 @@ static int ipmmu_attach_device(struct iommu_domain 
*io_domain,
                return -ENXIO;
        }
 
-       spin_lock_irqsave(&domain->lock, flags);
+       mutex_lock(&domain->mutex);
 
        if (!domain->mmu) {
                /* The domain hasn't been used yet, initialize it. */
@@ -674,7 +673,7 @@ static int ipmmu_attach_device(struct iommu_domain 
*io_domain,
        } else
                dev_info(dev, "Reusing IPMMU context %u\n", domain->context_id);
 
-       spin_unlock_irqrestore(&domain->lock, flags);
+       mutex_unlock(&domain->mutex);
 
        if (ret < 0)
                return ret;
-- 
2.17.1

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