From edc81dcd5b7f699c4049042b35c904396642032e Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 22 Aug 2018 17:55:46 -0400 Subject: [PATCH] SUNRPC: Refactor xprt_transmit() to remove the reply queue code Separate out the action of adding a request to the reply queue so that the backchannel code can simply skip calling it altogether. Signed-off-by: Trond Myklebust --- include/linux/sunrpc/xprt.h | 1 + net/sunrpc/backchannel_rqst.c | 1 - net/sunrpc/clnt.c | 5 ++ net/sunrpc/xprt.c | 127 +++++++++++++++++++----------- net/sunrpc/xprtrdma/backchannel.c | 1 - 5 files changed, 89 insertions(+), 46 deletions(-) diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index c25d0a5fda69..0250294c904a 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -334,6 +334,7 @@ void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req); void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task); bool xprt_prepare_transmit(struct rpc_task *task); +void xprt_request_enqueue_receive(struct rpc_task *task); void xprt_transmit(struct rpc_task *task); void xprt_end_transmit(struct rpc_task *task); int xprt_adjust_timeout(struct rpc_rqst *req); diff --git a/net/sunrpc/backchannel_rqst.c b/net/sunrpc/backchannel_rqst.c index 3c15a99b9700..fa5ba6ed3197 100644 --- a/net/sunrpc/backchannel_rqst.c +++ b/net/sunrpc/backchannel_rqst.c @@ -91,7 +91,6 @@ struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags) return NULL; req->rq_xprt = xprt; - INIT_LIST_HEAD(&req->rq_list); INIT_LIST_HEAD(&req->rq_bc_list); /* Preallocate one XDR receive buffer */ diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index a858366cd15d..414966273a3f 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1962,6 +1962,11 @@ call_transmit(struct rpc_task *task) return; } } + + /* Add task to reply queue before transmission to avoid races */ + if (rpc_reply_expected(task)) + xprt_request_enqueue_receive(task); + if (!xprt_prepare_transmit(task)) return; task->tk_action = call_transmit_status; diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 6e3d4b4ee79e..2ae0a4c47d59 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -888,6 +888,62 @@ static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req) wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req)); } +static bool +xprt_request_data_received(struct rpc_task *task) +{ + return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) && + READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0; +} + +static bool +xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req) +{ + return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) && + READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0; +} + +/** + * xprt_request_enqueue_receive - Add an request to the receive queue + * @task: RPC task + * + */ +void +xprt_request_enqueue_receive(struct rpc_task *task) +{ + struct rpc_rqst *req = task->tk_rqstp; + struct rpc_xprt *xprt = req->rq_xprt; + + if (!xprt_request_need_enqueue_receive(task, req)) + return; + spin_lock(&xprt->queue_lock); + + /* Update the softirq receive buffer */ + memcpy(&req->rq_private_buf, &req->rq_rcv_buf, + sizeof(req->rq_private_buf)); + + /* Add request to the receive list */ + list_add_tail(&req->rq_list, &xprt->recv); + set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate); + spin_unlock(&xprt->queue_lock); + + xprt_reset_majortimeo(req); + /* Turn off autodisconnect */ + del_singleshot_timer_sync(&xprt->timer); +} + +/** + * xprt_request_dequeue_receive_locked - Remove a request from the receive queue + * @task: RPC task + * + * Caller must hold xprt->queue_lock. + */ +static void +xprt_request_dequeue_receive_locked(struct rpc_task *task) +{ + if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) + list_del(&task->tk_rqstp->rq_list); +} + /** * xprt_update_rtt - Update RPC RTT statistics * @task: RPC request that recently completed @@ -927,24 +983,16 @@ void xprt_complete_rqst(struct rpc_task *task, int copied) xprt->stat.recvs++; - list_del_init(&req->rq_list); req->rq_private_buf.len = copied; /* Ensure all writes are done before we update */ /* req->rq_reply_bytes_recvd */ smp_wmb(); req->rq_reply_bytes_recvd = copied; - clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate); + xprt_request_dequeue_receive_locked(task); rpc_wake_up_queued_task(&xprt->pending, task); } EXPORT_SYMBOL_GPL(xprt_complete_rqst); -static bool -xprt_request_data_received(struct rpc_task *task) -{ - return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) && - task->tk_rqstp->rq_reply_bytes_recvd != 0; -} - static void xprt_timer(struct rpc_task *task) { struct rpc_rqst *req = task->tk_rqstp; @@ -1018,32 +1066,15 @@ void xprt_transmit(struct rpc_task *task) dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen); - if (!req->rq_reply_bytes_recvd) { - + if (!req->rq_bytes_sent) { + if (xprt_request_data_received(task)) + return; /* Verify that our message lies in the RPCSEC_GSS window */ - if (!req->rq_bytes_sent && rpcauth_xmit_need_reencode(task)) { + if (rpcauth_xmit_need_reencode(task)) { task->tk_status = -EBADMSG; return; } - - if (list_empty(&req->rq_list) && rpc_reply_expected(task)) { - /* - * Add to the list only if we're expecting a reply - */ - /* Update the softirq receive buffer */ - memcpy(&req->rq_private_buf, &req->rq_rcv_buf, - sizeof(req->rq_private_buf)); - /* Add request to the receive list */ - spin_lock(&xprt->queue_lock); - list_add_tail(&req->rq_list, &xprt->recv); - set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate); - spin_unlock(&xprt->queue_lock); - xprt_reset_majortimeo(req); - /* Turn off autodisconnect */ - del_singleshot_timer_sync(&xprt->timer); - } - } else if (xprt_request_data_received(task) && !req->rq_bytes_sent) - return; + } connect_cookie = xprt->connect_cookie; status = xprt->ops->send_request(task); @@ -1285,7 +1316,6 @@ xprt_request_init(struct rpc_task *task) struct rpc_xprt *xprt = task->tk_xprt; struct rpc_rqst *req = task->tk_rqstp; - INIT_LIST_HEAD(&req->rq_list); req->rq_timeout = task->tk_client->cl_timeout->to_initval; req->rq_task = task; req->rq_xprt = xprt; @@ -1355,6 +1385,26 @@ void xprt_retry_reserve(struct rpc_task *task) xprt_do_reserve(xprt, task); } +static void +xprt_request_dequeue_all(struct rpc_task *task, struct rpc_rqst *req) +{ + struct rpc_xprt *xprt = req->rq_xprt; + + if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) || + xprt_is_pinned_rqst(req)) { + spin_lock(&xprt->queue_lock); + xprt_request_dequeue_receive_locked(task); + while (xprt_is_pinned_rqst(req)) { + set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate); + spin_unlock(&xprt->queue_lock); + xprt_wait_on_pinned_rqst(req); + spin_lock(&xprt->queue_lock); + clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate); + } + spin_unlock(&xprt->queue_lock); + } +} + /** * xprt_release - release an RPC request slot * @task: task which is finished with the slot @@ -1379,18 +1429,7 @@ void xprt_release(struct rpc_task *task) task->tk_ops->rpc_count_stats(task, task->tk_calldata); else if (task->tk_client) rpc_count_iostats(task, task->tk_client->cl_metrics); - spin_lock(&xprt->queue_lock); - if (!list_empty(&req->rq_list)) { - list_del_init(&req->rq_list); - if (xprt_is_pinned_rqst(req)) { - set_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate); - spin_unlock(&xprt->queue_lock); - xprt_wait_on_pinned_rqst(req); - spin_lock(&xprt->queue_lock); - clear_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate); - } - } - spin_unlock(&xprt->queue_lock); + xprt_request_dequeue_all(task, req); spin_lock_bh(&xprt->transport_lock); xprt->ops->release_xprt(xprt, task); if (xprt->ops->release_request) diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c index 90adeff4c06b..ed58761e6b23 100644 --- a/net/sunrpc/xprtrdma/backchannel.c +++ b/net/sunrpc/xprtrdma/backchannel.c @@ -51,7 +51,6 @@ static int rpcrdma_bc_setup_reqs(struct rpcrdma_xprt *r_xprt, rqst = &req->rl_slot; rqst->rq_xprt = xprt; - INIT_LIST_HEAD(&rqst->rq_list); INIT_LIST_HEAD(&rqst->rq_bc_list); __set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); spin_lock_bh(&xprt->bc_pa_lock);