From 39494194f93bed7926d4b3bd03a6a76ba23e612b Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 5 Oct 2022 15:57:35 -0400 Subject: SUNRPC: Fix races with rpc_killall_tasks() 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 Signed-off-by: Anna Schumaker --- include/linux/sunrpc/sched.h | 1 + net/sunrpc/clnt.c | 6 ++---- net/sunrpc/sched.c | 40 +++++++++++++++++++++++++--------------- net/sunrpc/xprtsock.c | 3 +-- 4 files changed, 29 insertions(+), 21 deletions(-) diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h index acc62647317c..647247040ef9 100644 --- a/include/linux/sunrpc/sched.h +++ b/include/linux/sunrpc/sched.h @@ -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); diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 4d8665f15dd7..a8c341e43510 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -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; diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 25b9221950ff..f388bfaf6ff0 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -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); } diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index b3341c202ea0..f34d5427b66c 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -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); -- cgit v1.2.3