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iommu/amd: Make amd_iommu_devtable_lock a spin_lock 

Before commit 0bb6e243d7 ("iommu/amd: Support IOMMU_DOMAIN_DMA type
allocation") amd_iommu_devtable_lock had a read_lock() user but now
there are none. In fact, after the mentioned commit we had only
write_lock() user of the lock. Since there is no reason to keep it as
writer lock, change its type to a spin_lock.
I *think* that we might even be able to remove the lock because all its
current user seem to have their own protection.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Sebastian Andrzej Siewior 2018-03-22 16:22:41 +01:00 committed by Joerg Roedel
parent 993ca6e063
commit 2cd1083d79
1 changed files with 7 additions and 7 deletions
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14
drivers/iommu/amd_iommu.c
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@ -80,7 +80,7 @@
*/
#define AMD_IOMMU_PGSIZES ((~0xFFFUL) & ~(2ULL << 38))
static DEFINE_RWLOCK(amd_iommu_devtable_lock);
static DEFINE_SPINLOCK(amd_iommu_devtable_lock);
static DEFINE_SPINLOCK(pd_bitmap_lock);
static DEFINE_SPINLOCK(iommu_table_lock);
@ -2097,9 +2097,9 @@ static int attach_device(struct device *dev,
}
skip_ats_check:
write_lock_irqsave(&amd_iommu_devtable_lock, flags);
spin_lock_irqsave(&amd_iommu_devtable_lock, flags);
ret = __attach_device(dev_data, domain);
write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
/*
* We might boot into a crash-kernel here. The crashed kernel
@ -2149,9 +2149,9 @@ static void detach_device(struct device *dev)
domain = dev_data->domain;
/* lock device table */
write_lock_irqsave(&amd_iommu_devtable_lock, flags);
spin_lock_irqsave(&amd_iommu_devtable_lock, flags);
__detach_device(dev_data);
write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
if (!dev_is_pci(dev))
return;
@ -2814,7 +2814,7 @@ static void cleanup_domain(struct protection_domain *domain)
struct iommu_dev_data *entry;
unsigned long flags;
write_lock_irqsave(&amd_iommu_devtable_lock, flags);
spin_lock_irqsave(&amd_iommu_devtable_lock, flags);
while (!list_empty(&domain->dev_list)) {
entry = list_first_entry(&domain->dev_list,
@ -2822,7 +2822,7 @@ static void cleanup_domain(struct protection_domain *domain)
__detach_device(entry);
}
write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
spin_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
}
static void protection_domain_free(struct protection_domain *domain)