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authorChuck Lever <chuck.lever@oracle.com>2020-05-02 17:37:44 +0300
committerChuck Lever <chuck.lever@oracle.com>2020-05-18 17:21:21 +0300
commitca4faf543a33373bed3650812d5f0cd0bd295b1a (patch)
tree557c33f5f34050f49e27961857ba4e52ad4945da /net/sunrpc/svcsock.c
parentb9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce (diff)
downloadlinux-ca4faf543a33373bed3650812d5f0cd0bd295b1a.tar.xz
SUNRPC: Move xpt_mutex into socket xpo_sendto methods
It appears that the RPC/RDMA transport does not need serialization of calls to its xpo_sendto method. Move the mutex into the socket methods that still need that serialization. Tail latencies are unambiguously better with this patch applied. fio randrw 8KB 70/30 on NFSv3, smaller numbers are better: clat percentiles (usec): With xpt_mutex: r | 99.99th=[ 8848] w | 99.99th=[ 9634] Without xpt_mutex: r | 99.99th=[ 8586] w | 99.99th=[ 8979] Serializing the construction of RPC/RDMA transport headers is not really necessary at this point, because the Linux NFS server implementation never changes its credit grant on a connection. If that should change, then svc_rdma_sendto will need to serialize access to the transport's credit grant fields. Reported-by: kbuild test robot <lkp@intel.com> [ cel: fix uninitialized variable warning ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc/svcsock.c')
-rw-r--r--net/sunrpc/svcsock.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 023514e392b3..3e7b6445e317 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -506,6 +506,9 @@ out_free:
* svc_udp_sendto - Send out a reply on a UDP socket
* @rqstp: completed svc_rqst
*
+ * xpt_mutex ensures @rqstp's whole message is written to the socket
+ * without interruption.
+ *
* Returns the number of bytes sent, or a negative errno.
*/
static int svc_udp_sendto(struct svc_rqst *rqstp)
@@ -531,6 +534,11 @@ static int svc_udp_sendto(struct svc_rqst *rqstp)
svc_set_cmsg_data(rqstp, cmh);
+ mutex_lock(&xprt->xpt_mutex);
+
+ if (svc_xprt_is_dead(xprt))
+ goto out_notconn;
+
err = xprt_sock_sendmsg(svsk->sk_sock, &msg, xdr, 0, 0, &sent);
xdr_free_bvec(xdr);
if (err == -ECONNREFUSED) {
@@ -538,9 +546,15 @@ static int svc_udp_sendto(struct svc_rqst *rqstp)
err = xprt_sock_sendmsg(svsk->sk_sock, &msg, xdr, 0, 0, &sent);
xdr_free_bvec(xdr);
}
+
+ mutex_unlock(&xprt->xpt_mutex);
if (err < 0)
return err;
return sent;
+
+out_notconn:
+ mutex_unlock(&xprt->xpt_mutex);
+ return -ENOTCONN;
}
static int svc_udp_has_wspace(struct svc_xprt *xprt)
@@ -1063,6 +1077,9 @@ err_noclose:
* svc_tcp_sendto - Send out a reply on a TCP socket
* @rqstp: completed svc_rqst
*
+ * xpt_mutex ensures @rqstp's whole message is written to the socket
+ * without interruption.
+ *
* Returns the number of bytes sent, or a negative errno.
*/
static int svc_tcp_sendto(struct svc_rqst *rqstp)
@@ -1080,12 +1097,19 @@ static int svc_tcp_sendto(struct svc_rqst *rqstp)
svc_release_skb(rqstp);
+ mutex_lock(&xprt->xpt_mutex);
+ if (svc_xprt_is_dead(xprt))
+ goto out_notconn;
err = xprt_sock_sendmsg(svsk->sk_sock, &msg, xdr, 0, marker, &sent);
xdr_free_bvec(xdr);
if (err < 0 || sent != (xdr->len + sizeof(marker)))
goto out_close;
+ mutex_unlock(&xprt->xpt_mutex);
return sent;
+out_notconn:
+ mutex_unlock(&xprt->xpt_mutex);
+ return -ENOTCONN;
out_close:
pr_notice("rpc-srv/tcp: %s: %s %d when sending %d bytes - shutting down socket\n",
xprt->xpt_server->sv_name,
@@ -1093,6 +1117,7 @@ out_close:
(err < 0) ? err : sent, xdr->len);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
svc_xprt_enqueue(xprt);
+ mutex_unlock(&xprt->xpt_mutex);
return -EAGAIN;
}