All of lore.kernel.org
 help / color / mirror / Atom feed
From: Trond Myklebust <Trond.Myklebust@netapp.com>
To: stable@vger.kernel.org
Cc: linux-nfs@vger.kernel.org, Bryan Schumaker <bjschuma@netapp.com>
Subject: [PATCH] SUNRPC: Fix a UDP transport regression
Date: Mon, 22 Oct 2012 12:56:58 -0400	[thread overview]
Message-ID: <1350925018-12926-1-git-send-email-Trond.Myklebust@netapp.com> (raw)

commit f39c1bfb5a03e2d255451bff05be0d7255298fa4 and
commit 84e28a307e376f271505af65a7b7e212dd6f61f4 upstream.

Commit 43cedbf0e8dfb9c5610eb7985d5f21263e313802 (SUNRPC: Ensure that
we grab the XPRT_LOCK before calling xprt_alloc_slot) is causing
hangs in the case of NFS over UDP mounts.

Since neither the UDP or the RDMA transport mechanism use dynamic slot
allocation, we can skip grabbing the socket lock for those transports.
Add a new rpc_xprt_op to allow switching between the TCP and UDP/RDMA
case.

Note that the NFSv4.1 back channel assigns the slot directly
through rpc_run_bc_task, so we can ignore that case.

Reported-by: Dick Streefland <dick.streefland@altium.nl>
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
Please apply to all stable kernels >= 3.1 and <=3.5

Thanks!
   Trond

 include/linux/sunrpc/xprt.h     |  3 +++
 net/sunrpc/xprt.c               | 34 ++++++++++++++++++++--------------
 net/sunrpc/xprtrdma/transport.c |  1 +
 net/sunrpc/xprtsock.c           |  4 ++++
 4 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 77d278d..005b507 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -114,6 +114,7 @@ struct rpc_xprt_ops {
 	void		(*set_buffer_size)(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize);
 	int		(*reserve_xprt)(struct rpc_xprt *xprt, struct rpc_task *task);
 	void		(*release_xprt)(struct rpc_xprt *xprt, struct rpc_task *task);
+	void		(*alloc_slot)(struct rpc_xprt *xprt, struct rpc_task *task);
 	void		(*rpcbind)(struct rpc_task *task);
 	void		(*set_port)(struct rpc_xprt *xprt, unsigned short port);
 	void		(*connect)(struct rpc_task *task);
@@ -279,6 +280,8 @@ void			xprt_connect(struct rpc_task *task);
 void			xprt_reserve(struct rpc_task *task);
 int			xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
 int			xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
+void			xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task);
+void			xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task);
 int			xprt_prepare_transmit(struct rpc_task *task);
 void			xprt_transmit(struct rpc_task *task);
 void			xprt_end_transmit(struct rpc_task *task);
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index da72492..176a24f 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -969,11 +969,11 @@ static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 	return false;
 }
 
-static void xprt_alloc_slot(struct rpc_task *task)
+void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
 {
-	struct rpc_xprt	*xprt = task->tk_xprt;
 	struct rpc_rqst *req;
 
+	spin_lock(&xprt->reserve_lock);
 	if (!list_empty(&xprt->free)) {
 		req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
 		list_del(&req->rq_list);
@@ -994,12 +994,29 @@ static void xprt_alloc_slot(struct rpc_task *task)
 	default:
 		task->tk_status = -EAGAIN;
 	}
+	spin_unlock(&xprt->reserve_lock);
 	return;
 out_init_req:
 	task->tk_status = 0;
 	task->tk_rqstp = req;
 	xprt_request_init(task, xprt);
+	spin_unlock(&xprt->reserve_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_alloc_slot);
+
+void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+	/* Note: grabbing the xprt_lock_write() ensures that we throttle
+	 * new slot allocation if the transport is congested (i.e. when
+	 * reconnecting a stream transport or when out of socket write
+	 * buffer space).
+	 */
+	if (xprt_lock_write(xprt, task)) {
+		xprt_alloc_slot(xprt, task);
+		xprt_release_write(xprt, task);
+	}
 }
+EXPORT_SYMBOL_GPL(xprt_lock_and_alloc_slot);
 
 static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
 {
@@ -1083,20 +1100,9 @@ void xprt_reserve(struct rpc_task *task)
 	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;
-
-	spin_lock(&xprt->reserve_lock);
-	xprt_alloc_slot(task);
-	spin_unlock(&xprt->reserve_lock);
-	xprt_release_write(xprt, task);
+	xprt->ops->alloc_slot(xprt, task);
 }
 
 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 06cdbff..5d9202d 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -713,6 +713,7 @@ static void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 static struct rpc_xprt_ops xprt_rdma_procs = {
 	.reserve_xprt		= xprt_rdma_reserve_xprt,
 	.release_xprt		= xprt_release_xprt_cong, /* sunrpc/xprt.c */
+	.alloc_slot		= xprt_alloc_slot,
 	.release_request	= xprt_release_rqst_cong,       /* ditto */
 	.set_retrans_timeout	= xprt_set_retrans_timeout_def, /* ditto */
 	.rpcbind		= rpcb_getport_async,	/* sunrpc/rpcb_clnt.c */
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 00ff343..a4a6586 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2444,6 +2444,7 @@ static void bc_destroy(struct rpc_xprt *xprt)
 static struct rpc_xprt_ops xs_local_ops = {
 	.reserve_xprt		= xprt_reserve_xprt,
 	.release_xprt		= xs_tcp_release_xprt,
+	.alloc_slot		= xprt_alloc_slot,
 	.rpcbind		= xs_local_rpcbind,
 	.set_port		= xs_local_set_port,
 	.connect		= xs_connect,
@@ -2460,6 +2461,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
 	.set_buffer_size	= xs_udp_set_buffer_size,
 	.reserve_xprt		= xprt_reserve_xprt_cong,
 	.release_xprt		= xprt_release_xprt_cong,
+	.alloc_slot		= xprt_alloc_slot,
 	.rpcbind		= rpcb_getport_async,
 	.set_port		= xs_set_port,
 	.connect		= xs_connect,
@@ -2477,6 +2479,7 @@ static struct rpc_xprt_ops xs_udp_ops = {
 static struct rpc_xprt_ops xs_tcp_ops = {
 	.reserve_xprt		= xprt_reserve_xprt,
 	.release_xprt		= xs_tcp_release_xprt,
+	.alloc_slot		= xprt_lock_and_alloc_slot,
 	.rpcbind		= rpcb_getport_async,
 	.set_port		= xs_set_port,
 	.connect		= xs_connect,
@@ -2496,6 +2499,7 @@ static struct rpc_xprt_ops xs_tcp_ops = {
 static struct rpc_xprt_ops bc_tcp_ops = {
 	.reserve_xprt		= xprt_reserve_xprt,
 	.release_xprt		= xprt_release_xprt,
+	.alloc_slot		= xprt_alloc_slot,
 	.rpcbind		= xs_local_rpcbind,
 	.buf_alloc		= bc_malloc,
 	.buf_free		= bc_free,
-- 
1.7.11.7


             reply	other threads:[~2012-10-22 16:57 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-22 16:56 Trond Myklebust [this message]
2012-10-27 23:33 ` [PATCH] SUNRPC: Fix a UDP transport regression Ben Hutchings

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1350925018-12926-1-git-send-email-Trond.Myklebust@netapp.com \
    --to=trond.myklebust@netapp.com \
    --cc=bjschuma@netapp.com \
    --cc=linux-nfs@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.