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>

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 68a15a0..541d210 100644 (file)
--- 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;
 }