RDMA: Handle PD allocations by IB/core

The PD allocations in IB/core allows us to simplify drivers and their
error flows in their .alloc_pd() paths. The changes in .alloc_pd() go hand
in had with relevant update in .dealloc_pd().

We will use this opportunity and convert .dealloc_pd() to don't fail, as
it was suggested a long time ago, failures are not happening as we have
never seen a WARN_ON print.

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/sw/rxe/rxe_pool.c

@@ -46,6 +46,7 @@ struct rxe_type_info rxe_type_info[RXE_NUM_TYPES] = {
 	[RXE_TYPE_PD] = {
 		.name		= "rxe-pd",
 		.size		= sizeof(struct rxe_pd),
+		.flags		= RXE_POOL_NO_ALLOC,
 	},
 	[RXE_TYPE_AH] = {
 		.name		= "rxe-ah",
@@ -119,8 +120,10 @@ static void rxe_cache_clean(size_t cnt)
 
 	for (i = 0; i < cnt; i++) {
 		type = &rxe_type_info[i];
-		kmem_cache_destroy(type->cache);
-		type->cache = NULL;
+		if (!(type->flags & RXE_POOL_NO_ALLOC)) {
+			kmem_cache_destroy(type->cache);
+			type->cache = NULL;
+		}
 	}
 }
 
@@ -134,14 +137,17 @@ int rxe_cache_init(void)
 	for (i = 0; i < RXE_NUM_TYPES; i++) {
 		type = &rxe_type_info[i];
 		size = ALIGN(type->size, RXE_POOL_ALIGN);
-		type->cache = kmem_cache_create(type->name, size,
-				RXE_POOL_ALIGN,
-				RXE_POOL_CACHE_FLAGS, NULL);
-		if (!type->cache) {
-			pr_err("Unable to init kmem cache for %s\n",
-			       type->name);
-			err = -ENOMEM;
-			goto err1;
+		if (!(type->flags & RXE_POOL_NO_ALLOC)) {
+			type->cache =
+				kmem_cache_create(type->name, size,
+						  RXE_POOL_ALIGN,
+						  RXE_POOL_CACHE_FLAGS, NULL);
+			if (!type->cache) {
+				pr_err("Unable to init kmem cache for %s\n",
+				       type->name);
+				err = -ENOMEM;
+				goto err1;
+			}
 		}
 	}
 
@@ -415,6 +421,37 @@ out_put_pool:
 	return NULL;
 }
 
+int rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_entry *elem)
+{
+	unsigned long flags;
+
+	might_sleep_if(!(pool->flags & RXE_POOL_ATOMIC));
+
+	read_lock_irqsave(&pool->pool_lock, flags);
+	if (pool->state != RXE_POOL_STATE_VALID) {
+		read_unlock_irqrestore(&pool->pool_lock, flags);
+		return -EINVAL;
+	}
+	kref_get(&pool->ref_cnt);
+	read_unlock_irqrestore(&pool->pool_lock, flags);
+
+	kref_get(&pool->rxe->ref_cnt);
+
+	if (atomic_inc_return(&pool->num_elem) > pool->max_elem)
+		goto out_put_pool;
+
+	elem->pool = pool;
+	kref_init(&elem->ref_cnt);
+
+	return 0;
+
+out_put_pool:
+	atomic_dec(&pool->num_elem);
+	rxe_dev_put(pool->rxe);
+	rxe_pool_put(pool);
+	return -EINVAL;
+}
+
 void rxe_elem_release(struct kref *kref)
 {
 	struct rxe_pool_entry *elem =
@@ -424,7 +461,8 @@ void rxe_elem_release(struct kref *kref)
 	if (pool->cleanup)
 		pool->cleanup(elem);
 
-	kmem_cache_free(pool_cache(pool), elem);
+	if (!(pool->flags & RXE_POOL_NO_ALLOC))
+		kmem_cache_free(pool_cache(pool), elem);
 	atomic_dec(&pool->num_elem);
 	rxe_dev_put(pool->rxe);
 	rxe_pool_put(pool);

drivers/infiniband/sw/rxe/rxe_pool.h

@@ -41,6 +41,7 @@ enum rxe_pool_flags {
 	RXE_POOL_ATOMIC		= BIT(0),
 	RXE_POOL_INDEX		= BIT(1),
 	RXE_POOL_KEY		= BIT(2),
+	RXE_POOL_NO_ALLOC	= BIT(4),
 };
 
 enum rxe_elem_type {
@@ -131,6 +132,9 @@ void rxe_pool_cleanup(struct rxe_pool *pool);
 /* allocate an object from pool */
 void *rxe_alloc(struct rxe_pool *pool);
 
+/* connect already allocated object to pool */
+int rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_entry *elem);
+
 /* assign an index to an indexed object and insert object into
  *  pool's rb tree
  */

drivers/infiniband/sw/rxe/rxe_verbs.c

@@ -191,23 +191,20 @@ static int rxe_port_immutable(struct ib_device *dev, u8 port_num,
 	return 0;
 }
 
-static struct ib_pd *rxe_alloc_pd(struct ib_device *dev,
-				  struct ib_ucontext *context,
-				  struct ib_udata *udata)
+static int rxe_alloc_pd(struct ib_pd *ibpd, struct ib_ucontext *context,
+			struct ib_udata *udata)
 {
-	struct rxe_dev *rxe = to_rdev(dev);
-	struct rxe_pd *pd;
+	struct rxe_dev *rxe = to_rdev(ibpd->device);
+	struct rxe_pd *pd = to_rpd(ibpd);
 
-	pd = rxe_alloc(&rxe->pd_pool);
-	return pd ? &pd->ibpd : ERR_PTR(-ENOMEM);
+	return rxe_add_to_pool(&rxe->pd_pool, &pd->pelem);
 }
 
-static int rxe_dealloc_pd(struct ib_pd *ibpd)
+static void rxe_dealloc_pd(struct ib_pd *ibpd)
 {
 	struct rxe_pd *pd = to_rpd(ibpd);
 
 	rxe_drop_ref(pd);
-	return 0;
 }
 
 static struct ib_ah *rxe_create_ah(struct ib_pd *ibpd,
@@ -1183,6 +1180,7 @@ static const struct ib_device_ops rxe_dev_ops = {
 	.reg_user_mr = rxe_reg_user_mr,
 	.req_notify_cq = rxe_req_notify_cq,
 	.resize_cq = rxe_resize_cq,
+	INIT_RDMA_OBJ_SIZE(ib_pd, rxe_pd, ibpd),
 };
 
 int rxe_register_device(struct rxe_dev *rxe)

drivers/infiniband/sw/rxe/rxe_verbs.h

@@ -66,8 +66,8 @@ struct rxe_ucontext {
 };
 
 struct rxe_pd {
+	struct ib_pd            ibpd;
 	struct rxe_pool_entry	pelem;
-	struct ib_pd		ibpd;
 };
 
 struct rxe_ah {