intel-iommu: Remove superfluous iova_alloc_lock from IOVA code

We only ever obtain this lock immediately before the iova_rbtree_lock,
and release it immediately after the iova_rbtree_lock. So ditch it and
just use iova_rbtree_lock.

[v2: Remove the lockdep bits this time too]
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

3 files changed, 4 insertions, 16 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index c5f7c73cbb55..d6a857397ec3 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -1309,7 +1309,6 @@ static void iommu_detach_domain(struct dmar_domain *domain,
 }
 
 static struct iova_domain reserved_iova_list;
-static struct lock_class_key reserved_alloc_key;
 static struct lock_class_key reserved_rbtree_key;
 
 static void dmar_init_reserved_ranges(void)
@@ -1320,8 +1319,6 @@ static void dmar_init_reserved_ranges(void)
 
         init_iova_domain(&reserved_iova_list, DMA_32BIT_PFN);
 
-        lockdep_set_class(&reserved_iova_list.iova_alloc_lock,
-                &reserved_alloc_key);
         lockdep_set_class(&reserved_iova_list.iova_rbtree_lock,
                 &reserved_rbtree_key);
 
diff --git a/drivers/pci/iova.c b/drivers/pci/iova.c
index 46dd440e2315..7914951ef29a 100644
--- a/drivers/pci/iova.c
+++ b/drivers/pci/iova.c
@@ -22,7 +22,6 @@
 void
 init_iova_domain(struct iova_domain *iovad, unsigned long pfn_32bit)
 {
-        spin_lock_init(&iovad->iova_alloc_lock);
         spin_lock_init(&iovad->iova_rbtree_lock);
         iovad->rbroot = RB_ROOT;
         iovad->cached32_node = NULL;
@@ -205,7 +204,6 @@ alloc_iova(struct iova_domain *iovad, unsigned long size,
         unsigned long limit_pfn,
         bool size_aligned)
 {
-        unsigned long flags;
         struct iova *new_iova;
         int ret;
 
@@ -219,11 +217,9 @@ alloc_iova(struct iova_domain *iovad, unsigned long size,
         if (size_aligned)
                 size = __roundup_pow_of_two(size);
 
-        spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
         ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn,
                         new_iova, size_aligned);
 
-        spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
         if (ret) {
                 free_iova_mem(new_iova);
                 return NULL;
@@ -381,8 +377,7 @@ reserve_iova(struct iova_domain *iovad,
         struct iova *iova;
         unsigned int overlap = 0;
 
-        spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
-        spin_lock(&iovad->iova_rbtree_lock);
+        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
         for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
                 if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
                         iova = container_of(node, struct iova, node);
@@ -402,8 +397,7 @@ reserve_iova(struct iova_domain *iovad,
         iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
 finish:
 
-        spin_unlock(&iovad->iova_rbtree_lock);
-        spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
+        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
         return iova;
 }
 
@@ -420,8 +414,7 @@ copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
         unsigned long flags;
         struct rb_node *node;
 
-        spin_lock_irqsave(&from->iova_alloc_lock, flags);
-        spin_lock(&from->iova_rbtree_lock);
+        spin_lock_irqsave(&from->iova_rbtree_lock, flags);
         for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
                 struct iova *iova = container_of(node, struct iova, node);
                 struct iova *new_iova;
@@ -430,6 +423,5 @@ copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
                         printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
                                 iova->pfn_lo, iova->pfn_lo);
         }
-        spin_unlock(&from->iova_rbtree_lock);
-        spin_unlock_irqrestore(&from->iova_alloc_lock, flags);
+        spin_unlock_irqrestore(&from->iova_rbtree_lock, flags);
 }
diff --git a/include/linux/iova.h b/include/linux/iova.h
index 228f6c94b69c..76a0759e88ec 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -28,7 +28,6 @@ struct iova {
 
 /* holds all the iova translations for a domain */
 struct iova_domain {
-        spinlock_t      iova_alloc_lock;/* Lock to protect iova  allocation */
         spinlock_t      iova_rbtree_lock; /* Lock to protect update of rbtree */
         struct rb_root  rbroot;         /* iova domain rbtree root */
         struct rb_node  *cached32_node; /* Save last alloced node */