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SUNRPC: Fix races with rpc_killall_tasks()

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Ensure that we immediately call rpc_exit_task() after waking up, and
that the tk_rpc_status cannot get clobbered by some other function.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Trond Myklebust 2022-10-05 15:57:35 -04:00 committed by Anna Schumaker
parent e4266f23ec
commit 39494194f9
4 changed files with 29 additions and 21 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/linux/sunrpc/sched.h
View file

@ -209,6 +209,7 @@ struct rpc_task *rpc_run_task(const struct rpc_task_setup *);
struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req);
void rpc_put_task(struct rpc_task *);
void rpc_put_task_async(struct rpc_task *);
bool rpc_task_set_rpc_status(struct rpc_task *task, int rpc_status);
void rpc_signal_task(struct rpc_task *);
void rpc_exit_task(struct rpc_task *);
void rpc_exit(struct rpc_task *, int);

6
net/sunrpc/clnt.c
View file

@ -1642,7 +1642,7 @@ static void
__rpc_call_rpcerror(struct rpc_task *task, int tk_status, int rpc_status)
{
trace_rpc_call_rpcerror(task, tk_status, rpc_status);
task->tk_rpc_status = rpc_status;
rpc_task_set_rpc_status(task, rpc_status);
rpc_exit(task, tk_status);
}
@ -2435,10 +2435,8 @@ rpc_check_timeout(struct rpc_task *task)
{
struct rpc_clnt *clnt = task->tk_client;
if (RPC_SIGNALLED(task)) {
rpc_call_rpcerror(task, -ERESTARTSYS);
if (RPC_SIGNALLED(task))
return;
}
if (xprt_adjust_timeout(task->tk_rqstp) == 0)
return;

40
net/sunrpc/sched.c
View file

@ -65,6 +65,13 @@ gfp_t rpc_task_gfp_mask(void)
}
EXPORT_SYMBOL_GPL(rpc_task_gfp_mask);
bool rpc_task_set_rpc_status(struct rpc_task *task, int rpc_status)
{
if (cmpxchg(&task->tk_rpc_status, 0, rpc_status) == 0)
return true;
return false;
}
unsigned long
rpc_task_timeout(const struct rpc_task *task)
{
@ -855,12 +862,14 @@ void rpc_signal_task(struct rpc_task *task)
if (!RPC_IS_ACTIVATED(task))
return;
if (!rpc_task_set_rpc_status(task, -ERESTARTSYS))
return;
trace_rpc_task_signalled(task, task->tk_action);
set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
smp_mb__after_atomic();
queue = READ_ONCE(task->tk_waitqueue);
if (queue)
rpc_wake_up_queued_task_set_status(queue, task, -ERESTARTSYS);
rpc_wake_up_queued_task(queue, task);
}
void rpc_exit(struct rpc_task *task, int status)
@ -907,10 +916,16 @@ static void __rpc_execute(struct rpc_task *task)
* Perform the next FSM step or a pending callback.
*
* tk_action may be NULL if the task has been killed.
* In particular, note that rpc_killall_tasks may
* do this at any time, so beware when dereferencing.
*/
do_action = task->tk_action;
/* Tasks with an RPC error status should exit */
if (do_action != rpc_exit_task &&
(status = READ_ONCE(task->tk_rpc_status)) != 0) {
task->tk_status = status;
if (do_action != NULL)
do_action = rpc_exit_task;
}
/* Callbacks override all actions */
if (task->tk_callback) {
do_action = task->tk_callback;
task->tk_callback = NULL;
@ -932,14 +947,6 @@ static void __rpc_execute(struct rpc_task *task)
continue;
}
/*
* Signalled tasks should exit rather than sleep.
*/
if (RPC_SIGNALLED(task)) {
task->tk_rpc_status = -ERESTARTSYS;
rpc_exit(task, -ERESTARTSYS);
}
/*
* The queue->lock protects against races with
* rpc_make_runnable().
@ -955,6 +962,12 @@ static void __rpc_execute(struct rpc_task *task)
spin_unlock(&queue->lock);
continue;
}
/* Wake up any task that has an exit status */
if (READ_ONCE(task->tk_rpc_status) != 0) {
rpc_wake_up_task_queue_locked(queue, task);
spin_unlock(&queue->lock);
continue;
}
rpc_clear_running(task);
spin_unlock(&queue->lock);
if (task_is_async)
@ -972,10 +985,7 @@ static void __rpc_execute(struct rpc_task *task)
* clean up after sleeping on some queue, we don't
* break the loop here, but go around once more.
*/
trace_rpc_task_signalled(task, task->tk_action);
set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
task->tk_rpc_status = -ERESTARTSYS;
rpc_exit(task, -ERESTARTSYS);
rpc_signal_task(task);
}
trace_rpc_task_sync_wake(task, task->tk_action);
}

3
net/sunrpc/xprtsock.c
View file

@ -1978,8 +1978,7 @@ static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task)
* we'll need to figure out how to pass a namespace to
* connect.
*/
task->tk_rpc_status = -ENOTCONN;
rpc_exit(task, -ENOTCONN);
rpc_task_set_rpc_status(task, -ENOTCONN);
goto out_wake;
}
ret = xs_local_setup_socket(transport);