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[2603:8081:140c:1a00:bfc7:2889:1b58:2997]) by smtp.gmail.com with ESMTPSA id bf3sm2246594oib.34.2021.10.22.12.19.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Oct 2021 12:19:31 -0700 (PDT) From: Bob Pearson To: jgg@nvidia.com, zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org Cc: Bob Pearson Subject: [PATCH for-next v3 01/10] RDMA/rxe: Make rxe_alloc() take pool lock Date: Fri, 22 Oct 2021 14:18:16 -0500 Message-Id: <20211022191824.18307-2-rpearsonhpe@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211022191824.18307-1-rpearsonhpe@gmail.com> References: <20211022191824.18307-1-rpearsonhpe@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org In rxe_pool.c there are two separate pool APIs for creating a new object rxe_alloc() and rxe_alloc_locked(). Currently they are identical except for GFP_KERNEL vs GFP_ATOMIC. Make rxe_alloc() take the pool lock which is in line with the other APIs in the library and was the original intent. Keep kzalloc() outside of the lock to avoid using GFP_ATOMIC. Make similar change to rxe_add_to_pool. The code checking the pool limit is potentially racy without a lock. The lock around finishing the pool element provides a memory barrier before 'publishing' the object. Signed-off-by: Bob Pearson --- v3 Kept rxe_alloc and rxe_alloc_locked separate to allow use of GFP_KERNEL in rxe_alloc drivers/infiniband/sw/rxe/rxe_pool.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c index 7b4cb46edfd9..8138e459b6c1 100644 --- a/drivers/infiniband/sw/rxe/rxe_pool.c +++ b/drivers/infiniband/sw/rxe/rxe_pool.c @@ -356,39 +356,51 @@ void *rxe_alloc(struct rxe_pool *pool) { struct rxe_type_info *info = &rxe_type_info[pool->type]; struct rxe_pool_entry *elem; + unsigned long flags; u8 *obj; + write_lock_irqsave(&pool->pool_lock, flags); if (atomic_inc_return(&pool->num_elem) > pool->max_elem) goto out_cnt; + write_unlock_irqrestore(&pool->pool_lock, flags); obj = kzalloc(info->size, GFP_KERNEL); - if (!obj) - goto out_cnt; + if (!obj) { + atomic_dec(&pool->num_elem); + return NULL; + } + write_lock_irqsave(&pool->pool_lock, flags); elem = (struct rxe_pool_entry *)(obj + info->elem_offset); - elem->pool = pool; kref_init(&elem->ref_cnt); + write_unlock_irqrestore(&pool->pool_lock, flags); return obj; out_cnt: atomic_dec(&pool->num_elem); + write_unlock_irqrestore(&pool->pool_lock, flags); return NULL; } int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_entry *elem) { + unsigned long flags; + + write_lock_irqsave(&pool->pool_lock, flags); if (atomic_inc_return(&pool->num_elem) > pool->max_elem) goto out_cnt; elem->pool = pool; kref_init(&elem->ref_cnt); + write_unlock_irqrestore(&pool->pool_lock, flags); return 0; out_cnt: atomic_dec(&pool->num_elem); + write_unlock_irqrestore(&pool->pool_lock, flags); return -EINVAL; } -- 2.30.2