From 43cedbf0e8dfb9c5610eb7985d5f21263e313802 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 17 Jul 2011 16:01:03 -0400 Subject: SUNRPC: Ensure that we grab the XPRT_LOCK before calling xprt_alloc_slot This throttles the allocation of new slots when the socket is busy reconnecting and/or is out of buffer space. Signed-off-by: Trond Myklebust --- net/sunrpc/xprt.c | 66 +++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 42 insertions(+), 24 deletions(-) (limited to 'net/sunrpc/xprt.c') diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index fbdbaf2cd58..ccd583a46ff 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -191,10 +191,9 @@ EXPORT_SYMBOL_GPL(xprt_load_transport); * transport connects from colliding with writes. No congestion control * is provided. */ -int xprt_reserve_xprt(struct rpc_task *task) +int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task) { struct rpc_rqst *req = task->tk_rqstp; - struct rpc_xprt *xprt = req->rq_xprt; if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) { if (task == xprt->snd_task) @@ -202,8 +201,10 @@ int xprt_reserve_xprt(struct rpc_task *task) goto out_sleep; } xprt->snd_task = task; - req->rq_bytes_sent = 0; - req->rq_ntrans++; + if (req != NULL) { + req->rq_bytes_sent = 0; + req->rq_ntrans++; + } return 1; @@ -212,7 +213,7 @@ out_sleep: task->tk_pid, xprt); task->tk_timeout = 0; task->tk_status = -EAGAIN; - if (req->rq_ntrans) + if (req != NULL && req->rq_ntrans) rpc_sleep_on(&xprt->resend, task, NULL); else rpc_sleep_on(&xprt->sending, task, NULL); @@ -239,9 +240,8 @@ static void xprt_clear_locked(struct rpc_xprt *xprt) * integrated into the decision of whether a request is allowed to be * woken up and given access to the transport. */ -int xprt_reserve_xprt_cong(struct rpc_task *task) +int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task) { - struct rpc_xprt *xprt = task->tk_xprt; struct rpc_rqst *req = task->tk_rqstp; if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) { @@ -249,12 +249,14 @@ int xprt_reserve_xprt_cong(struct rpc_task *task) return 1; goto out_sleep; } + if (req == NULL) { + xprt->snd_task = task; + return 1; + } if (__xprt_get_cong(xprt, task)) { xprt->snd_task = task; - if (req) { - req->rq_bytes_sent = 0; - req->rq_ntrans++; - } + req->rq_bytes_sent = 0; + req->rq_ntrans++; return 1; } xprt_clear_locked(xprt); @@ -262,7 +264,7 @@ out_sleep: dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt); task->tk_timeout = 0; task->tk_status = -EAGAIN; - if (req && req->rq_ntrans) + if (req != NULL && req->rq_ntrans) rpc_sleep_on(&xprt->resend, task, NULL); else rpc_sleep_on(&xprt->sending, task, NULL); @@ -275,7 +277,7 @@ static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task) int retval; spin_lock_bh(&xprt->transport_lock); - retval = xprt->ops->reserve_xprt(task); + retval = xprt->ops->reserve_xprt(xprt, task); spin_unlock_bh(&xprt->transport_lock); return retval; } @@ -291,7 +293,7 @@ static void __xprt_lock_write_next(struct rpc_xprt *xprt) task = rpc_wake_up_next(&xprt->resend); if (!task) { task = rpc_wake_up_next(&xprt->sending); - if (!task) + if (task == NULL) goto out_unlock; } @@ -310,6 +312,7 @@ out_unlock: static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt) { struct rpc_task *task; + struct rpc_rqst *req; if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) return; @@ -318,16 +321,19 @@ static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt) task = rpc_wake_up_next(&xprt->resend); if (!task) { task = rpc_wake_up_next(&xprt->sending); - if (!task) + if (task == NULL) goto out_unlock; } + + req = task->tk_rqstp; + if (req == NULL) { + xprt->snd_task = task; + return; + } if (__xprt_get_cong(xprt, task)) { - struct rpc_rqst *req = task->tk_rqstp; xprt->snd_task = task; - if (req) { - req->rq_bytes_sent = 0; - req->rq_ntrans++; - } + req->rq_bytes_sent = 0; + req->rq_ntrans++; return; } out_unlock: @@ -852,7 +858,7 @@ int xprt_prepare_transmit(struct rpc_task *task) err = req->rq_reply_bytes_recvd; goto out_unlock; } - if (!xprt->ops->reserve_xprt(task)) + if (!xprt->ops->reserve_xprt(xprt, task)) err = -EAGAIN; out_unlock: spin_unlock_bh(&xprt->transport_lock); @@ -933,8 +939,6 @@ static void xprt_alloc_slot(struct rpc_task *task) struct rpc_xprt *xprt = task->tk_xprt; task->tk_status = 0; - if (task->tk_rqstp) - return; if (!list_empty(&xprt->free)) { struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list); list_del_init(&req->rq_list); @@ -944,7 +948,6 @@ static void xprt_alloc_slot(struct rpc_task *task) } dprintk("RPC: waiting for request slot\n"); task->tk_status = -EAGAIN; - task->tk_timeout = 0; rpc_sleep_on(&xprt->backlog, task, NULL); } @@ -1001,10 +1004,25 @@ void xprt_reserve(struct rpc_task *task) { struct rpc_xprt *xprt = task->tk_xprt; + task->tk_status = 0; + if (task->tk_rqstp != NULL) + return; + + /* Note: grabbing the xprt_lock_write() here is not strictly needed, + * but ensures that we throttle new slot allocation if the transport + * is congested (e.g. if reconnecting or if we're out of socket + * write buffer space). + */ + task->tk_timeout = 0; + task->tk_status = -EAGAIN; + if (!xprt_lock_write(xprt, task)) + return; + task->tk_status = -EIO; spin_lock(&xprt->reserve_lock); xprt_alloc_slot(task); spin_unlock(&xprt->reserve_lock); + xprt_release_write(xprt, task); } static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt) -- cgit v1.2.3