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SUNRPC: Clean up transport write space handling 

Treat socket write space handling in the same way we now treat transport
congestion: by denying the XPRT_LOCK until the transport signals that it
has free buffer space.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2018-09-03 23:39:27 -04:00
parent 36bd7de949
commit c544577dad
8 changed files with 73 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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

@ -84,7 +84,6 @@ struct svc_xprt {
struct sockaddr_storage xpt_remote; /* remote peer's address */
size_t xpt_remotelen; /* length of address */
char xpt_remotebuf[INET6_ADDRSTRLEN + 10];
struct rpc_wait_queue xpt_bc_pending; /* backchannel wait queue */
struct list_head xpt_users; /* callbacks on free */
struct net *xpt_net;

5
include/linux/sunrpc/xprt.h
View File

@ -387,8 +387,8 @@ int xprt_load_transport(const char *);
void xprt_set_retrans_timeout_def(struct rpc_task *task);
void xprt_set_retrans_timeout_rtt(struct rpc_task *task);
void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status);
void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action);
void xprt_write_space(struct rpc_xprt *xprt);
void xprt_wait_for_buffer_space(struct rpc_xprt *xprt);
bool xprt_write_space(struct rpc_xprt *xprt);
void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result);
struct rpc_rqst * xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid);
void xprt_update_rtt(struct rpc_task *task);
@ -416,6 +416,7 @@ void xprt_unlock_connect(struct rpc_xprt *, void *);
#define XPRT_CLOSING (6)
#define XPRT_CONGESTED (9)
#define XPRT_CWND_WAIT (10)
#define XPRT_WRITE_SPACE (11)
static inline void xprt_set_connected(struct rpc_xprt *xprt)
{

28
net/sunrpc/clnt.c
View File

@ -1964,13 +1964,14 @@ call_transmit(struct rpc_task *task)
{
dprint_status(task);
task->tk_status = 0;
if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) {
if (!xprt_prepare_transmit(task))
return;
xprt_transmit(task);
}
task->tk_action = call_transmit_status;
if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
return;
if (!xprt_prepare_transmit(task))
return;
xprt_transmit(task);
xprt_end_transmit(task);
}
/*
@ -1986,7 +1987,6 @@ call_transmit_status(struct rpc_task *task)
* test first.
*/
if (task->tk_status == 0) {
xprt_end_transmit(task);
xprt_request_wait_receive(task);
return;
}
@ -1994,15 +1994,8 @@ call_transmit_status(struct rpc_task *task)
switch (task->tk_status) {
default:
dprint_status(task);
xprt_end_transmit(task);
break;
case -EBADSLT:
xprt_end_transmit(task);
task->tk_action = call_transmit;
task->tk_status = 0;
break;
case -EBADMSG:
xprt_end_transmit(task);
task->tk_status = 0;
task->tk_action = call_encode;
break;
@ -2015,6 +2008,7 @@ call_transmit_status(struct rpc_task *task)
case -ENOBUFS:
rpc_delay(task, HZ>>2);
/* fall through */
case -EBADSLT:
case -EAGAIN:
task->tk_action = call_transmit;
task->tk_status = 0;
@ -2026,7 +2020,6 @@ call_transmit_status(struct rpc_task *task)
case -ENETUNREACH:
case -EPERM:
if (RPC_IS_SOFTCONN(task)) {
xprt_end_transmit(task);
if (!task->tk_msg.rpc_proc->p_proc)
trace_xprt_ping(task->tk_xprt,
task->tk_status);
@ -2069,9 +2062,6 @@ call_bc_transmit(struct rpc_task *task)
xprt_transmit(task);
if (task->tk_status == -EAGAIN)
goto out_retry;
xprt_end_transmit(task);
dprint_status(task);
switch (task->tk_status) {
@ -2087,6 +2077,8 @@ call_bc_transmit(struct rpc_task *task)
case -ENOTCONN:
case -EPIPE:
break;
case -EAGAIN:
goto out_retry;
case -ETIMEDOUT:
/*
* Problem reaching the server. Disconnect and let the

2
net/sunrpc/svc_xprt.c
View File

@ -171,7 +171,6 @@ void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl,
mutex_init(&xprt->xpt_mutex);
spin_lock_init(&xprt->xpt_lock);
set_bit(XPT_BUSY, &xprt->xpt_flags);
rpc_init_wait_queue(&xprt->xpt_bc_pending, "xpt_bc_pending");
xprt->xpt_net = get_net(net);
strcpy(xprt->xpt_remotebuf, "uninitialized");
}
@ -895,7 +894,6 @@ int svc_send(struct svc_rqst *rqstp)
else
len = xprt->xpt_ops->xpo_sendto(rqstp);
mutex_unlock(&xprt->xpt_mutex);
rpc_wake_up(&xprt->xpt_bc_pending);
trace_svc_send(rqstp, len);
svc_xprt_release(rqstp);

77
net/sunrpc/xprt.c
View File

@ -169,6 +169,17 @@ int xprt_load_transport(const char *transport_name)
}
EXPORT_SYMBOL_GPL(xprt_load_transport);
static void xprt_clear_locked(struct rpc_xprt *xprt)
{
xprt->snd_task = NULL;
if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
smp_mb__before_atomic();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_atomic();
} else
queue_work(xprtiod_workqueue, &xprt->task_cleanup);
}
/**
* xprt_reserve_xprt - serialize write access to transports
* @task: task that is requesting access to the transport
@ -188,10 +199,14 @@ int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
return 1;
goto out_sleep;
}
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
xprt->snd_task = task;
return 1;
out_unlock:
xprt_clear_locked(xprt);
out_sleep:
dprintk("RPC: %5u failed to lock transport %p\n",
task->tk_pid, xprt);
@ -208,17 +223,6 @@ int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
}
EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
static void xprt_clear_locked(struct rpc_xprt *xprt)
{
xprt->snd_task = NULL;
if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
smp_mb__before_atomic();
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_atomic();
} else
queue_work(xprtiod_workqueue, &xprt->task_cleanup);
}
static bool
xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
{
@ -267,10 +271,13 @@ int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
xprt->snd_task = task;
return 1;
}
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
if (!xprt_need_congestion_window_wait(xprt)) {
xprt->snd_task = task;
return 1;
}
out_unlock:
xprt_clear_locked(xprt);
out_sleep:
dprintk("RPC: %5u failed to lock transport %p\n", task->tk_pid, xprt);
@ -309,10 +316,12 @@ static void __xprt_lock_write_next(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
__xprt_lock_write_func, xprt))
return;
out_unlock:
xprt_clear_locked(xprt);
}
@ -320,6 +329,8 @@ static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
{
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
return;
if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
goto out_unlock;
if (xprt_need_congestion_window_wait(xprt))
goto out_unlock;
if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
@ -510,39 +521,46 @@ EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
/**
* xprt_wait_for_buffer_space - wait for transport output buffer to clear
* @task: task to be put to sleep
* @action: function pointer to be executed after wait
* @xprt: transport
*
* Note that we only set the timer for the case of RPC_IS_SOFT(), since
* we don't in general want to force a socket disconnection due to
* an incomplete RPC call transmission.
*/
void xprt_wait_for_buffer_space(struct rpc_task *task, rpc_action action)
void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
task->tk_timeout = RPC_IS_SOFT(task) ? req->rq_timeout : 0;
rpc_sleep_on(&xprt->pending, task, action);
set_bit(XPRT_WRITE_SPACE, &xprt->state);
}
EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
static bool
xprt_clear_write_space_locked(struct rpc_xprt *xprt)
{
if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
__xprt_lock_write_next(xprt);
dprintk("RPC: write space: waking waiting task on "
"xprt %p\n", xprt);
return true;
}
return false;
}
/**
* xprt_write_space - wake the task waiting for transport output buffer space
* @xprt: transport with waiting tasks
*
* Can be called in a soft IRQ context, so xprt_write_space never sleeps.
*/
void xprt_write_space(struct rpc_xprt *xprt)
bool xprt_write_space(struct rpc_xprt *xprt)
{
bool ret;
if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
return false;
spin_lock_bh(&xprt->transport_lock);
if (xprt->snd_task) {
dprintk("RPC: write space: waking waiting task on "
"xprt %p\n", xprt);
rpc_wake_up_queued_task_on_wq(xprtiod_workqueue,
&xprt->pending, xprt->snd_task);
}
ret = xprt_clear_write_space_locked(xprt);
spin_unlock_bh(&xprt->transport_lock);
return ret;
}
EXPORT_SYMBOL_GPL(xprt_write_space);
@ -653,6 +671,7 @@ void xprt_disconnect_done(struct rpc_xprt *xprt)
dprintk("RPC: disconnected transport %p\n", xprt);
spin_lock_bh(&xprt->transport_lock);
xprt_clear_connected(xprt);
xprt_clear_write_space_locked(xprt);
xprt_wake_pending_tasks(xprt, -EAGAIN);
spin_unlock_bh(&xprt->transport_lock);
}
@ -1326,9 +1345,7 @@ xprt_transmit(struct rpc_task *task)
if (!xprt_request_data_received(task) ||
test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
continue;
} else if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
rpc_wake_up_queued_task(&xprt->pending, task);
else
} else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
task->tk_status = status;
break;
}

2
net/sunrpc/xprtrdma/rpc_rdma.c
View File

@ -866,7 +866,7 @@ rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst)
out_err:
switch (ret) {
case -EAGAIN:
xprt_wait_for_buffer_space(rqst->rq_task, NULL);
xprt_wait_for_buffer_space(rqst->rq_xprt);
break;
case -ENOBUFS:
break;

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

@ -224,12 +224,7 @@ xprt_rdma_bc_send_request(struct rpc_rqst *rqst, struct rpc_task *task)
dprintk("svcrdma: sending bc call with xid: %08x\n",
be32_to_cpu(rqst->rq_xid));
if (!mutex_trylock(&sxprt->xpt_mutex)) {
rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
if (!mutex_trylock(&sxprt->xpt_mutex))
return -EAGAIN;
rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
}
mutex_lock(&sxprt->xpt_mutex);
ret = -ENOTCONN;
rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);

33
net/sunrpc/xprtsock.c
View File

@ -440,20 +440,12 @@ static int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
return err;
}
static void xs_nospace_callback(struct rpc_task *task)
{
struct sock_xprt *transport = container_of(task->tk_rqstp->rq_xprt, struct sock_xprt, xprt);
transport->inet->sk_write_pending--;
}
/**
* xs_nospace - place task on wait queue if transmit was incomplete
* xs_nospace - handle transmit was incomplete
* @req: pointer to RPC request
* @task: task to put to sleep
*
*/
static int xs_nospace(struct rpc_rqst *req, struct rpc_task *task)
static int xs_nospace(struct rpc_rqst *req)
{
struct rpc_xprt *xprt = req->rq_xprt;
struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
@ -461,7 +453,8 @@ static int xs_nospace(struct rpc_rqst *req, struct rpc_task *task)
int ret = -EAGAIN;
dprintk("RPC: %5u xmit incomplete (%u left of %u)\n",
task->tk_pid, req->rq_slen - transport->xmit.offset,
req->rq_task->tk_pid,
req->rq_slen - transport->xmit.offset,
req->rq_slen);
/* Protect against races with write_space */
@ -471,7 +464,7 @@ static int xs_nospace(struct rpc_rqst *req, struct rpc_task *task)
if (xprt_connected(xprt)) {
/* wait for more buffer space */
sk->sk_write_pending++;
xprt_wait_for_buffer_space(task, xs_nospace_callback);
xprt_wait_for_buffer_space(xprt);
} else
ret = -ENOTCONN;
@ -569,7 +562,7 @@ static int xs_local_send_request(struct rpc_rqst *req, struct rpc_task *task)
case -ENOBUFS:
break;
case -EAGAIN:
status = xs_nospace(req, task);
status = xs_nospace(req);
break;
default:
dprintk("RPC: sendmsg returned unrecognized error %d\n",
@ -642,7 +635,7 @@ static int xs_udp_send_request(struct rpc_rqst *req, struct rpc_task *task)
/* Should we call xs_close() here? */
break;
case -EAGAIN:
status = xs_nospace(req, task);
status = xs_nospace(req);
break;
case -ENETUNREACH:
case -ENOBUFS:
@ -765,7 +758,7 @@ static int xs_tcp_send_request(struct rpc_rqst *req, struct rpc_task *task)
/* Should we call xs_close() here? */
break;
case -EAGAIN:
status = xs_nospace(req, task);
status = xs_nospace(req);
break;
case -ECONNRESET:
case -ECONNREFUSED:
@ -1672,7 +1665,8 @@ static void xs_write_space(struct sock *sk)
if (!wq || test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &wq->flags) == 0)
goto out;
xprt_write_space(xprt);
if (xprt_write_space(xprt))
sk->sk_write_pending--;
out:
rcu_read_unlock();
}
@ -2725,12 +2719,7 @@ static int bc_send_request(struct rpc_rqst *req, struct rpc_task *task)
* Grab the mutex to serialize data as the connection is shared
* with the fore channel
*/
if (!mutex_trylock(&xprt->xpt_mutex)) {
rpc_sleep_on(&xprt->xpt_bc_pending, task, NULL);
if (!mutex_trylock(&xprt->xpt_mutex))
return -EAGAIN;
rpc_wake_up_queued_task(&xprt->xpt_bc_pending, task);
}
mutex_lock(&xprt->xpt_mutex);
if (test_bit(XPT_DEAD, &xprt->xpt_flags))
len = -ENOTCONN;
else