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SUNRPC: Fix up RPC back channel transmission 

Now that transmissions happen through a queue, we require the RPC tasks
to handle error conditions that may have been set while they were
sleeping. The back channel does not currently do this, but assumes
that any error condition happens during its own call to xprt_transmit().

The solution is to ensure that the back channel splits out the
error handling just like the forward channel does.

Fixes: 89f90fe1ad ("SUNRPC: Allow calls to xprt_transmit() to drain...")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2019-03-05 07:30:48 -05:00
parent ed7dc973bd
commit 477687e111
1 changed files with 34 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
net/sunrpc/clnt.c
View File

@ -66,9 +66,6 @@ static void call_decode(struct rpc_task *task);
static void call_bind(struct rpc_task *task);
static void call_bind_status(struct rpc_task *task);
static void call_transmit(struct rpc_task *task);
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static void call_bc_transmit(struct rpc_task *task);
#endif /* CONFIG_SUNRPC_BACKCHANNEL */
static void call_status(struct rpc_task *task);
static void call_transmit_status(struct rpc_task *task);
static void call_refresh(struct rpc_task *task);
@ -1133,6 +1130,8 @@ rpc_call_async(struct rpc_clnt *clnt, const struct rpc_message *msg, int flags,
EXPORT_SYMBOL_GPL(rpc_call_async);
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static void call_bc_encode(struct rpc_task *task);
/**
* rpc_run_bc_task - Allocate a new RPC task for backchannel use, then run
* rpc_execute against it
@ -1154,7 +1153,7 @@ struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req)
task = rpc_new_task(&task_setup_data);
xprt_init_bc_request(req, task);
task->tk_action = call_bc_transmit;
task->tk_action = call_bc_encode;
atomic_inc(&task->tk_count);
WARN_ON_ONCE(atomic_read(&task->tk_count) != 2);
rpc_execute(task);
@ -2085,33 +2084,40 @@ call_transmit_status(struct rpc_task *task)
}
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
static void call_bc_transmit(struct rpc_task *task);
static void call_bc_transmit_status(struct rpc_task *task);
static void
call_bc_encode(struct rpc_task *task)
{
xprt_request_enqueue_transmit(task);
task->tk_action = call_bc_transmit;
}
/*
* 5b. Send the backchannel RPC reply. On error, drop the reply. In
* addition, disconnect on connectivity errors.
*/
static void
call_bc_transmit(struct rpc_task *task)
{
task->tk_action = call_bc_transmit_status;
if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) {
if (!xprt_prepare_transmit(task))
return;
task->tk_status = 0;
xprt_transmit(task);
}
xprt_end_transmit(task);
}
static void
call_bc_transmit_status(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
if (rpc_task_need_encode(task))
xprt_request_enqueue_transmit(task);
if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
goto out_wakeup;
if (!xprt_prepare_transmit(task))
goto out_retry;
if (task->tk_status < 0) {
printk(KERN_NOTICE "RPC: Could not send backchannel reply "
"error: %d\n", task->tk_status);
goto out_done;
}
xprt_transmit(task);
xprt_end_transmit(task);
dprint_status(task);
switch (task->tk_status) {
case 0:
/* Success */
@ -2125,8 +2131,14 @@ call_bc_transmit(struct rpc_task *task)
case -ENOTCONN:
case -EPIPE:
break;
case -ENOBUFS:
rpc_delay(task, HZ>>2);
/* fall through */
case -EBADSLT:
case -EAGAIN:
goto out_retry;
task->tk_status = 0;
task->tk_action = call_bc_transmit;
return;
case -ETIMEDOUT:
/*
* Problem reaching the server. Disconnect and let the
@ -2145,18 +2157,11 @@ call_bc_transmit(struct rpc_task *task)
* We were unable to reply and will have to drop the
* request. The server should reconnect and retransmit.
*/
WARN_ON_ONCE(task->tk_status == -EAGAIN);
printk(KERN_NOTICE "RPC: Could not send backchannel reply "
"error: %d\n", task->tk_status);
break;
}
out_wakeup:
rpc_wake_up_queued_task(&req->rq_xprt->pending, task);
out_done:
task->tk_action = rpc_exit_task;
return;
out_retry:
task->tk_status = 0;
}
#endif /* CONFIG_SUNRPC_BACKCHANNEL */