iommu/tegra: Don't call alloc_pdir with as->lock

Instead of taking as->lock before calling alloc_pdir() and
releasing it in that function to allocate memory, just take
the lock only in the alloc_pdir function and run the loop
without any lock held. This simplifies the complicated
lock->unlock->alloc->lock->unlock sequence into
alloc->lock->unlock.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 16 insertions, 13 deletions

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 68a15a0d5b8a..541d210cb421 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -553,11 +553,11 @@ static inline void put_signature(struct smmu_as *as,
 #endif
 
 /*
- * Caller must lock/unlock as
+ * Caller must not hold as->lock
  */
-static int alloc_pdir(struct smmu_as *as, unsigned long *flags)
+static int alloc_pdir(struct smmu_as *as)
 {
-        unsigned long *pdir;
+        unsigned long *pdir, flags;
         int pdn, err = 0;
         u32 val;
         struct smmu_device *smmu = as->smmu;
@@ -565,13 +565,14 @@ static int alloc_pdir(struct smmu_as *as, unsigned long *flags)
         unsigned int *cnt;
 
         /*
-         * do the allocation outside the as->lock
+         * do the allocation, then grab as->lock
          */
-        spin_unlock_irqrestore(&as->lock, *flags);
         cnt = devm_kzalloc(smmu->dev,
-                           sizeof(cnt[0]) * SMMU_PDIR_COUNT, GFP_KERNEL);
+                           sizeof(cnt[0]) * SMMU_PDIR_COUNT,
+                           GFP_KERNEL);
         page = alloc_page(GFP_KERNEL | __GFP_DMA);
-        spin_lock_irqsave(&as->lock, *flags);
+
+        spin_lock_irqsave(&as->lock, flags);
 
         if (as->pdir_page) {
                 /* We raced, free the redundant */
@@ -603,9 +604,13 @@ static int alloc_pdir(struct smmu_as *as, unsigned long *flags)
         smmu_write(smmu, val, SMMU_TLB_FLUSH);
         FLUSH_SMMU_REGS(as->smmu);
 
+        spin_unlock_irqrestore(&as->lock, flags);
+
         return 0;
 
 err_out:
+        spin_unlock_irqrestore(&as->lock, flags);
+
         devm_kfree(smmu->dev, cnt);
         if (page)
                 __free_page(page);
@@ -809,13 +814,11 @@ static int smmu_iommu_domain_init(struct iommu_domain *domain)
         /* Look for a free AS with lock held */
         for  (i = 0; i < smmu->num_as; i++) {
                 as = &smmu->as[i];
-                spin_lock_irqsave(&as->lock, flags);
                 if (!as->pdir_page) {
-                        err = alloc_pdir(as, &flags);
+                        err = alloc_pdir(as);
                         if (!err)
                                 goto found;
                 }
-                spin_unlock_irqrestore(&as->lock, flags);
                 if (err != -EAGAIN)
                         break;
         }
@@ -824,7 +827,7 @@ static int smmu_iommu_domain_init(struct iommu_domain *domain)
         return err;
 
 found:
-        spin_lock(&smmu->lock);
+        spin_lock_irqsave(&smmu->lock, flags);
 
         /* Update PDIR register */
         smmu_write(smmu, SMMU_PTB_ASID_CUR(as->asid), SMMU_PTB_ASID);
@@ -832,12 +835,12 @@ found:
                    SMMU_MK_PDIR(as->pdir_page, as->pdir_attr), SMMU_PTB_DATA);
         FLUSH_SMMU_REGS(smmu);
 
-        spin_unlock(&smmu->lock);
+        spin_unlock_irqrestore(&smmu->lock, flags);
 
-        spin_unlock_irqrestore(&as->lock, flags);
         domain->priv = as;
 
         dev_dbg(smmu->dev, "smmu_as@%p\n", as);
+
         return 0;
 }