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SUNRPC: Add a separate spinlock to protect the RPC request receive list

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This further reduces contention with the transport_lock, and allows us
to convert to using a non-bh-safe spinlock, since the list is now never
accessed from a bh context.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2017-08-16 15:30:35 -04:00
parent 040249dfbe
commit ce7c252a8c
6 changed files with 41 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sunrpc/xprt.h
View File

@ -232,6 +232,7 @@ struct rpc_xprt {
*/
spinlock_t transport_lock; /* lock transport info */
spinlock_t reserve_lock; /* lock slot table */
spinlock_t recv_lock; /* lock receive list */
u32 xid; /* Next XID value to use */
struct rpc_task * snd_task; /* Task blocked in send */
struct svc_xprt *bc_xprt; /* NFSv4.1 backchannel */

6
net/sunrpc/svcsock.c
View File

@ -1001,7 +1001,7 @@ static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp)
if (!bc_xprt)
return -EAGAIN;
spin_lock_bh(&bc_xprt->transport_lock);
spin_lock(&bc_xprt->recv_lock);
req = xprt_lookup_rqst(bc_xprt, xid);
if (!req)
goto unlock_notfound;
@ -1019,7 +1019,7 @@ static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp)
memcpy(dst->iov_base, src->iov_base, src->iov_len);
xprt_complete_rqst(req->rq_task, rqstp->rq_arg.len);
rqstp->rq_arg.len = 0;
spin_unlock_bh(&bc_xprt->transport_lock);
spin_unlock(&bc_xprt->recv_lock);
return 0;
unlock_notfound:
printk(KERN_NOTICE
@ -1028,7 +1028,7 @@ unlock_notfound:
__func__, ntohl(calldir),
bc_xprt, ntohl(xid));
unlock_eagain:
spin_unlock_bh(&bc_xprt->transport_lock);
spin_unlock(&bc_xprt->recv_lock);
return -EAGAIN;
}

20
net/sunrpc/xprt.c
View File

@ -872,17 +872,17 @@ void xprt_unpin_rqst(struct rpc_rqst *req)
}
static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
__must_hold(&req->rq_xprt->transport_lock)
__must_hold(&req->rq_xprt->recv_lock)
{
struct rpc_task *task = req->rq_task;
if (task && test_bit(RPC_TASK_MSG_RECV, &task->tk_runstate)) {
spin_unlock_bh(&req->rq_xprt->transport_lock);
spin_unlock(&req->rq_xprt->recv_lock);
set_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
wait_on_bit(&task->tk_runstate, RPC_TASK_MSG_RECV,
TASK_UNINTERRUPTIBLE);
clear_bit(RPC_TASK_MSG_RECV_WAIT, &task->tk_runstate);
spin_lock_bh(&req->rq_xprt->transport_lock);
spin_lock(&req->rq_xprt->recv_lock);
}
}
@ -1008,13 +1008,13 @@ void xprt_transmit(struct rpc_task *task)
/*
* Add to the list only if we're expecting a reply
*/
spin_lock_bh(&xprt->transport_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 */
spin_lock(&xprt->recv_lock);
list_add_tail(&req->rq_list, &xprt->recv);
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
xprt_reset_majortimeo(req);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
@ -1329,15 +1329,18 @@ 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->recv_lock);
if (!list_empty(&req->rq_list)) {
list_del(&req->rq_list);
xprt_wait_on_pinned_rqst(req);
}
spin_unlock(&xprt->recv_lock);
spin_lock_bh(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
if (xprt->ops->release_request)
xprt->ops->release_request(task);
if (!list_empty(&req->rq_list))
list_del(&req->rq_list);
xprt->last_used = jiffies;
xprt_schedule_autodisconnect(xprt);
xprt_wait_on_pinned_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
if (req->rq_buffer)
xprt->ops->buf_free(task);
@ -1361,6 +1364,7 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
spin_lock_init(&xprt->transport_lock);
spin_lock_init(&xprt->reserve_lock);
spin_lock_init(&xprt->recv_lock);
INIT_LIST_HEAD(&xprt->free);
INIT_LIST_HEAD(&xprt->recv);

8
net/sunrpc/xprtrdma/rpc_rdma.c
View File

@ -1051,7 +1051,7 @@ rpcrdma_reply_handler(struct work_struct *work)
* RPC completion while holding the transport lock to ensure
* the rep, rqst, and rq_task pointers remain stable.
*/
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
rqst = xprt_lookup_rqst(xprt, headerp->rm_xid);
if (!rqst)
goto out_norqst;
@ -1136,7 +1136,7 @@ out:
xprt_release_rqst_cong(rqst->rq_task);
xprt_complete_rqst(rqst->rq_task, status);
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
dprintk("RPC: %s: xprt_complete_rqst(0x%p, 0x%p, %d)\n",
__func__, xprt, rqst, status);
return;
@ -1187,12 +1187,12 @@ out_rdmaerr:
r_xprt->rx_stats.bad_reply_count++;
goto out;
/* The req was still available, but by the time the transport_lock
/* The req was still available, but by the time the recv_lock
* was acquired, the rqst and task had been released. Thus the RPC
* has already been terminated.
*/
out_norqst:
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
rpcrdma_buffer_put(req);
dprintk("RPC: %s: race, no rqst left for req %p\n",
__func__, req);

7
net/sunrpc/xprtrdma/svc_rdma_backchannel.c
View File

@ -52,7 +52,7 @@ int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
if (src->iov_len < 24)
goto out_shortreply;
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
req = xprt_lookup_rqst(xprt, xid);
if (!req)
goto out_notfound;
@ -69,17 +69,20 @@ int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
credits = r_xprt->rx_buf.rb_bc_max_requests;
spin_lock_bh(&xprt->transport_lock);
cwnd = xprt->cwnd;
xprt->cwnd = credits << RPC_CWNDSHIFT;
if (xprt->cwnd > cwnd)
xprt_release_rqst_cong(req->rq_task);
spin_unlock_bh(&xprt->transport_lock);
ret = 0;
xprt_complete_rqst(req->rq_task, rcvbuf->len);
rcvbuf->len = 0;
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
out:
return ret;

30
net/sunrpc/xprtsock.c
View File

@ -969,12 +969,12 @@ static void xs_local_data_read_skb(struct rpc_xprt *xprt,
return;
/* Look up and lock the request corresponding to the given XID */
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
rovr = xprt_lookup_rqst(xprt, *xp);
if (!rovr)
goto out_unlock;
xprt_pin_rqst(rovr);
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
task = rovr->rq_task;
copied = rovr->rq_private_buf.buflen;
@ -983,16 +983,16 @@ static void xs_local_data_read_skb(struct rpc_xprt *xprt,
if (xs_local_copy_to_xdr(&rovr->rq_private_buf, skb)) {
dprintk("RPC: sk_buff copy failed\n");
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
goto out_unpin;
}
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
xprt_complete_rqst(task, copied);
out_unpin:
xprt_unpin_rqst(rovr);
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
}
static void xs_local_data_receive(struct sock_xprt *transport)
@ -1055,12 +1055,12 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
return;
/* Look up and lock the request corresponding to the given XID */
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
rovr = xprt_lookup_rqst(xprt, *xp);
if (!rovr)
goto out_unlock;
xprt_pin_rqst(rovr);
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
task = rovr->rq_task;
if ((copied = rovr->rq_private_buf.buflen) > repsize)
@ -1069,7 +1069,7 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
/* Suck it into the iovec, verify checksum if not done by hw. */
if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb)) {
__UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
goto out_unpin;
}
@ -1077,11 +1077,13 @@ static void xs_udp_data_read_skb(struct rpc_xprt *xprt,
spin_lock_bh(&xprt->transport_lock);
xprt_adjust_cwnd(xprt, task, copied);
spin_unlock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
xprt_complete_rqst(task, copied);
out_unpin:
xprt_unpin_rqst(rovr);
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
}
static void xs_udp_data_receive(struct sock_xprt *transport)
@ -1344,24 +1346,24 @@ static inline int xs_tcp_read_reply(struct rpc_xprt *xprt,
dprintk("RPC: read reply XID %08x\n", ntohl(transport->tcp_xid));
/* Find and lock the request corresponding to this xid */
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
req = xprt_lookup_rqst(xprt, transport->tcp_xid);
if (!req) {
dprintk("RPC: XID %08x request not found!\n",
ntohl(transport->tcp_xid));
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
return -1;
}
xprt_pin_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
xs_tcp_read_common(xprt, desc, req);
spin_lock_bh(&xprt->transport_lock);
spin_lock(&xprt->recv_lock);
if (!(transport->tcp_flags & TCP_RCV_COPY_DATA))
xprt_complete_rqst(req->rq_task, transport->tcp_copied);
xprt_unpin_rqst(req);
spin_unlock_bh(&xprt->transport_lock);
spin_unlock(&xprt->recv_lock);
return 0;
}