From: Sean Hefty Date: Wed, 13 Feb 2008 22:33:53 +0000 (-0800) Subject: RDMA/cma: Do not issue MRA if user rejects connection request X-Git-Tag: v2.6.25-rc2~8^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ead595aeb0974171eddd012df115424752413c26;p=linux-2.6 RDMA/cma: Do not issue MRA if user rejects connection request There's an undesirable interaction with issuing MRA requests to increase connection timeouts and the listen backlog. When the rdma_cm receives a connection request, it queues an MRA with the ib_cm. (The ib_cm will send an MRA if it receives a duplicate REQ.) The rdma_cm will then create a new rdma_cm_id and give that to the user, which in this case is the rdma_user_cm. If the listen backlog maintained in the rdma_user_cm is full, it destroys the rdma_cm_id, which in turns destroys the ib_cm_id. The ib_cm_id generates a REJ because the state of the ib_cm_id has changed to MRA sent, versus REQ received. When the backlog is full, we just want to drop the REQ so that it is retried later. Fix this by deferring queuing the MRA until after the user of the rdma_cm has examined the connection request. Signed-off-by: Sean Hefty Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index 1eff1b2c0e..34507daaf9 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -1107,7 +1107,6 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) event.param.ud.private_data_len = IB_CM_SIDR_REQ_PRIVATE_DATA_SIZE - offset; } else { - ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0); conn_id = cma_new_conn_id(&listen_id->id, ib_event); cma_set_req_event_data(&event, &ib_event->param.req_rcvd, ib_event->private_data, offset); @@ -1130,6 +1129,15 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) ret = conn_id->id.event_handler(&conn_id->id, &event); if (!ret) { + /* + * Acquire mutex to prevent user executing rdma_destroy_id() + * while we're accessing the cm_id. + */ + mutex_lock(&lock); + if (cma_comp(conn_id, CMA_CONNECT) && + !cma_is_ud_ps(conn_id->id.ps)) + ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0); + mutex_unlock(&lock); cma_enable_remove(conn_id); goto out; }