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Mon, 26 Oct 2020 09:01:23 -0700 Subject: Re: [PATCH] RDMA: Add rdma_connect_locked() To: Jason Gunthorpe , Danil Kipnis , Doug Ledford , Christoph Hellwig , Jack Wang , Keith Busch , linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, Max Gurtovoy , netdev@vger.kernel.org, rds-devel@oss.oracle.com, Sagi Grimberg Cc: Guoqing Jiang , Leon Romanovsky References: <0-v1-75e124dbad74+b05-rdma_connect_locking_jgg@nvidia.com> From: santosh.shilimkar@oracle.com Organization: Oracle Corporation Message-ID: Date: Mon, 26 Oct 2020 09:01:20 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <0-v1-75e124dbad74+b05-rdma_connect_locking_jgg@nvidia.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9785 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 impostorscore=0 adultscore=0 bulkscore=0 spamscore=0 phishscore=0 mlxlogscore=999 suspectscore=0 clxscore=1011 mlxscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010260110 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/26/20 7:25 AM, Jason Gunthorpe wrote: > There are two flows for handling RDMA_CM_EVENT_ROUTE_RESOLVED, either the > handler triggers a completion and another thread does rdma_connect() or > the handler directly calls rdma_connect(). > > In all cases rdma_connect() needs to hold the handler_mutex, but when > handler's are invoked this is already held by the core code. This causes > ULPs using the 2nd method to deadlock. > > Provide a rdma_connect_locked() and have all ULPs call it from their > handlers. > > Reported-by: Guoqing Jiang > Fixes: 2a7cec538169 ("RDMA/cma: Fix locking for the RDMA_CM_CONNECT state" > Signed-off-by: Jason Gunthorpe > --- [....] > diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c > index 06603dd1c8aa38..b36b60668b1da9 100644 > --- a/net/rds/ib_cm.c > +++ b/net/rds/ib_cm.c > @@ -956,9 +956,10 @@ int rds_ib_cm_initiate_connect(struct rdma_cm_id *cm_id, bool isv6) > rds_ib_cm_fill_conn_param(conn, &conn_param, &dp, > conn->c_proposed_version, > UINT_MAX, UINT_MAX, isv6); > - ret = rdma_connect(cm_id, &conn_param); > + ret = rdma_connect_locked(cm_id, &conn_param); > if (ret) > - rds_ib_conn_error(conn, "rdma_connect failed (%d)\n", ret); > + rds_ib_conn_error(conn, "rdma_connect_locked failed (%d)\n", > + ret); > > out: > /* Beware - returning non-zero tells the rdma_cm to destroy > For RDS part, Acked-by: Santosh Shilimkar