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SUNRPC: Refactor xprt_transmit() to remove the reply queue code

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Separate out the action of adding a request to the reply queue so that the
backchannel code can simply skip calling it altogether.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2018-08-22 17:55:46 -04:00
parent 75c84151a9
commit edc81dcd5b
5 changed files with 89 additions and 46 deletions
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1
include/linux/sunrpc/xprt.h
View File

@ -334,6 +334,7 @@ void xprt_free_slot(struct rpc_xprt *xprt,
struct rpc_rqst *req);
void xprt_lock_and_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task);
bool xprt_prepare_transmit(struct rpc_task *task);
void xprt_request_enqueue_receive(struct rpc_task *task);
void xprt_transmit(struct rpc_task *task);
void xprt_end_transmit(struct rpc_task *task);
int xprt_adjust_timeout(struct rpc_rqst *req);

1
net/sunrpc/backchannel_rqst.c
View File

@ -91,7 +91,6 @@ struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
return NULL;
req->rq_xprt = xprt;
INIT_LIST_HEAD(&req->rq_list);
INIT_LIST_HEAD(&req->rq_bc_list);
/* Preallocate one XDR receive buffer */

5
net/sunrpc/clnt.c
View File

@ -1962,6 +1962,11 @@ call_transmit(struct rpc_task *task)
return;
}
}
/* Add task to reply queue before transmission to avoid races */
if (rpc_reply_expected(task))
xprt_request_enqueue_receive(task);
if (!xprt_prepare_transmit(task))
return;
task->tk_action = call_transmit_status;

127
net/sunrpc/xprt.c
View File

@ -888,6 +888,62 @@ static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
}
static bool
xprt_request_data_received(struct rpc_task *task)
{
return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
}
static bool
xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
{
return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
}
/**
* xprt_request_enqueue_receive - Add an request to the receive queue
* @task: RPC task
*
*/
void
xprt_request_enqueue_receive(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
if (!xprt_request_need_enqueue_receive(task, req))
return;
spin_lock(&xprt->queue_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 */
list_add_tail(&req->rq_list, &xprt->recv);
set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
spin_unlock(&xprt->queue_lock);
xprt_reset_majortimeo(req);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
}
/**
* xprt_request_dequeue_receive_locked - Remove a request from the receive queue
* @task: RPC task
*
* Caller must hold xprt->queue_lock.
*/
static void
xprt_request_dequeue_receive_locked(struct rpc_task *task)
{
if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
list_del(&task->tk_rqstp->rq_list);
}
/**
* xprt_update_rtt - Update RPC RTT statistics
* @task: RPC request that recently completed
@ -927,24 +983,16 @@ void xprt_complete_rqst(struct rpc_task *task, int copied)
xprt->stat.recvs++;
list_del_init(&req->rq_list);
req->rq_private_buf.len = copied;
/* Ensure all writes are done before we update */
/* req->rq_reply_bytes_recvd */
smp_wmb();
req->rq_reply_bytes_recvd = copied;
clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
xprt_request_dequeue_receive_locked(task);
rpc_wake_up_queued_task(&xprt->pending, task);
}
EXPORT_SYMBOL_GPL(xprt_complete_rqst);
static bool
xprt_request_data_received(struct rpc_task *task)
{
return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
task->tk_rqstp->rq_reply_bytes_recvd != 0;
}
static void xprt_timer(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
@ -1018,32 +1066,15 @@ void xprt_transmit(struct rpc_task *task)
dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
if (!req->rq_reply_bytes_recvd) {
if (!req->rq_bytes_sent) {
if (xprt_request_data_received(task))
return;
/* Verify that our message lies in the RPCSEC_GSS window */
if (!req->rq_bytes_sent && rpcauth_xmit_need_reencode(task)) {
if (rpcauth_xmit_need_reencode(task)) {
task->tk_status = -EBADMSG;
return;
}
if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
/*
* Add to the list only if we're expecting a reply
*/
/* 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->queue_lock);
list_add_tail(&req->rq_list, &xprt->recv);
set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
spin_unlock(&xprt->queue_lock);
xprt_reset_majortimeo(req);
/* Turn off autodisconnect */
del_singleshot_timer_sync(&xprt->timer);
}
} else if (xprt_request_data_received(task) && !req->rq_bytes_sent)
return;
}
connect_cookie = xprt->connect_cookie;
status = xprt->ops->send_request(task);
@ -1285,7 +1316,6 @@ xprt_request_init(struct rpc_task *task)
struct rpc_xprt *xprt = task->tk_xprt;
struct rpc_rqst *req = task->tk_rqstp;
INIT_LIST_HEAD(&req->rq_list);
req->rq_timeout = task->tk_client->cl_timeout->to_initval;
req->rq_task = task;
req->rq_xprt = xprt;
@ -1355,6 +1385,26 @@ void xprt_retry_reserve(struct rpc_task *task)
xprt_do_reserve(xprt, task);
}
static void
xprt_request_dequeue_all(struct rpc_task *task, struct rpc_rqst *req)
{
struct rpc_xprt *xprt = req->rq_xprt;
if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
xprt_is_pinned_rqst(req)) {
spin_lock(&xprt->queue_lock);
xprt_request_dequeue_receive_locked(task);
while (xprt_is_pinned_rqst(req)) {
set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
spin_unlock(&xprt->queue_lock);
xprt_wait_on_pinned_rqst(req);
spin_lock(&xprt->queue_lock);
clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
}
spin_unlock(&xprt->queue_lock);
}
}
/**
* xprt_release - release an RPC request slot
* @task: task which is finished with the slot
@ -1379,18 +1429,7 @@ 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->queue_lock);
if (!list_empty(&req->rq_list)) {
list_del_init(&req->rq_list);
if (xprt_is_pinned_rqst(req)) {
set_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate);
spin_unlock(&xprt->queue_lock);
xprt_wait_on_pinned_rqst(req);
spin_lock(&xprt->queue_lock);
clear_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate);
}
}
spin_unlock(&xprt->queue_lock);
xprt_request_dequeue_all(task, req);
spin_lock_bh(&xprt->transport_lock);
xprt->ops->release_xprt(xprt, task);
if (xprt->ops->release_request)

1
net/sunrpc/xprtrdma/backchannel.c
View File

@ -51,7 +51,6 @@ static int rpcrdma_bc_setup_reqs(struct rpcrdma_xprt *r_xprt,
rqst = &req->rl_slot;
rqst->rq_xprt = xprt;
INIT_LIST_HEAD(&rqst->rq_list);
INIT_LIST_HEAD(&rqst->rq_bc_list);
__set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state);
spin_lock_bh(&xprt->bc_pa_lock);