IB/rxe: Replace spinlock with rwlock

Concurrent readers which read rb tree are protected using read lock.
Concurrent writers which add element to pool are protected
using write lock.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_pool.c

@@ -207,7 +207,7 @@ int rxe_pool_init(
 
 	kref_init(&pool->ref_cnt);
 
-	spin_lock_init(&pool->pool_lock);
+	rwlock_init(&pool->pool_lock);
 
 	if (rxe_type_info[type].flags & RXE_POOL_INDEX) {
 		err = rxe_pool_init_index(pool,
@@ -245,12 +245,12 @@ int rxe_pool_cleanup(struct rxe_pool *pool)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	write_lock_irqsave(&pool->pool_lock, flags);
 	pool->state = rxe_pool_invalid;
 	if (atomic_read(&pool->num_elem) > 0)
 		pr_warn("%s pool destroyed with unfree'd elem\n",
 			pool_name(pool));
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	write_unlock_irqrestore(&pool->pool_lock, flags);
 
 	rxe_pool_put(pool);
 
@@ -336,10 +336,10 @@ void rxe_add_key(void *arg, void *key)
 	struct rxe_pool *pool = elem->pool;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	write_lock_irqsave(&pool->pool_lock, flags);
 	memcpy((u8 *)elem + pool->key_offset, key, pool->key_size);
 	insert_key(pool, elem);
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	write_unlock_irqrestore(&pool->pool_lock, flags);
 }
 
 void rxe_drop_key(void *arg)
@@ -348,9 +348,9 @@ void rxe_drop_key(void *arg)
 	struct rxe_pool *pool = elem->pool;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	write_lock_irqsave(&pool->pool_lock, flags);
 	rb_erase(&elem->node, &pool->tree);
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	write_unlock_irqrestore(&pool->pool_lock, flags);
 }
 
 void rxe_add_index(void *arg)
@@ -359,10 +359,10 @@ void rxe_add_index(void *arg)
 	struct rxe_pool *pool = elem->pool;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	write_lock_irqsave(&pool->pool_lock, flags);
 	elem->index = alloc_index(pool);
 	insert_index(pool, elem);
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	write_unlock_irqrestore(&pool->pool_lock, flags);
 }
 
 void rxe_drop_index(void *arg)
@@ -371,10 +371,10 @@ void rxe_drop_index(void *arg)
 	struct rxe_pool *pool = elem->pool;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	write_lock_irqsave(&pool->pool_lock, flags);
 	clear_bit(elem->index - pool->min_index, pool->table);
 	rb_erase(&elem->node, &pool->tree);
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	write_unlock_irqrestore(&pool->pool_lock, flags);
 }
 
 void *rxe_alloc(struct rxe_pool *pool)
@@ -384,13 +384,13 @@ void *rxe_alloc(struct rxe_pool *pool)
 
 	might_sleep_if(!(pool->flags & RXE_POOL_ATOMIC));
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	read_lock_irqsave(&pool->pool_lock, flags);
 	if (pool->state != rxe_pool_valid) {
-		spin_unlock_irqrestore(&pool->pool_lock, flags);
+		read_unlock_irqrestore(&pool->pool_lock, flags);
 		return NULL;
 	}
 	kref_get(&pool->ref_cnt);
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	read_unlock_irqrestore(&pool->pool_lock, flags);
 
 	kref_get(&pool->rxe->ref_cnt);
 
@@ -436,7 +436,7 @@ void *rxe_pool_get_index(struct rxe_pool *pool, u32 index)
 	struct rxe_pool_entry *elem = NULL;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	read_lock_irqsave(&pool->pool_lock, flags);
 
 	if (pool->state != rxe_pool_valid)
 		goto out;
@@ -458,7 +458,7 @@ void *rxe_pool_get_index(struct rxe_pool *pool, u32 index)
 		kref_get(&elem->ref_cnt);
 
 out:
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	read_unlock_irqrestore(&pool->pool_lock, flags);
 	return node ? elem : NULL;
 }
 
@@ -469,7 +469,7 @@ void *rxe_pool_get_key(struct rxe_pool *pool, void *key)
 	int cmp;
 	unsigned long flags;
 
-	spin_lock_irqsave(&pool->pool_lock, flags);
+	read_lock_irqsave(&pool->pool_lock, flags);
 
 	if (pool->state != rxe_pool_valid)
 		goto out;
@@ -494,6 +494,6 @@ void *rxe_pool_get_key(struct rxe_pool *pool, void *key)
 		kref_get(&elem->ref_cnt);
 
 out:
-	spin_unlock_irqrestore(&pool->pool_lock, flags);
+	read_unlock_irqrestore(&pool->pool_lock, flags);
 	return node ? elem : NULL;
 }

drivers/infiniband/sw/rxe/rxe_pool.h

@@ -90,7 +90,7 @@ struct rxe_pool_entry {
 
 struct rxe_pool {
 	struct rxe_dev		*rxe;
-	spinlock_t              pool_lock; /* pool spinlock */
+	rwlock_t		pool_lock; /* protects pool add/del/search */
 	size_t			elem_size;
 	struct kref		ref_cnt;
 	void			(*cleanup)(struct rxe_pool_entry *obj);