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: NDavid Woodhouse <David.Woodhouse@intel.com>

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);
 

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);
 }

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 */