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 --- net/sunrpc/sched.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) (limited to 'net/sunrpc/sched.c') 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); } -- cgit v1.2.3 From f8423909ecca208834a9d704e58409800f8b5f21 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 5 Oct 2022 15:57:36 -0400 Subject: SUNRPC: Add a helper to allow pNFS drivers to selectively cancel RPC calls Add the helper rpc_cancel_tasks(), which uses a caller-defined selection function to define a set of in-flight RPC calls to cancel. This is mainly intended for pNFS drivers which are subject to a layout recall, and which may therefore want to cancel all pending I/O using that layout in order to redrive it after the layout recall has been satisfied. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker --- include/linux/sunrpc/sched.h | 5 +++++ net/sunrpc/clnt.c | 37 +++++++++++++++++++++++++++++++++++++ net/sunrpc/sched.c | 11 +++++++++++ 3 files changed, 53 insertions(+) (limited to 'net/sunrpc/sched.c') diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h index 647247040ef9..cdcf0fe56a6f 100644 --- a/include/linux/sunrpc/sched.h +++ b/include/linux/sunrpc/sched.h @@ -210,11 +210,16 @@ 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_task_try_cancel(struct rpc_task *task, int error); void rpc_signal_task(struct rpc_task *); void rpc_exit_task(struct rpc_task *); void rpc_exit(struct rpc_task *, int); void rpc_release_calldata(const struct rpc_call_ops *, void *); void rpc_killall_tasks(struct rpc_clnt *); +unsigned long rpc_cancel_tasks(struct rpc_clnt *clnt, int error, + bool (*fnmatch)(const struct rpc_task *, + const void *), + const void *data); void rpc_execute(struct rpc_task *); void rpc_init_priority_wait_queue(struct rpc_wait_queue *, const char *); void rpc_init_wait_queue(struct rpc_wait_queue *, const char *); diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index a8c341e43510..57677517b474 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -873,6 +873,43 @@ void rpc_killall_tasks(struct rpc_clnt *clnt) } EXPORT_SYMBOL_GPL(rpc_killall_tasks); +/** + * rpc_cancel_tasks - try to cancel a set of RPC tasks + * @clnt: Pointer to RPC client + * @error: RPC task error value to set + * @fnmatch: Pointer to selector function + * @data: User data + * + * Uses @fnmatch to define a set of RPC tasks that are to be cancelled. + * The argument @error must be a negative error value. + */ +unsigned long rpc_cancel_tasks(struct rpc_clnt *clnt, int error, + bool (*fnmatch)(const struct rpc_task *, + const void *), + const void *data) +{ + struct rpc_task *task; + unsigned long count = 0; + + if (list_empty(&clnt->cl_tasks)) + return 0; + /* + * Spin lock all_tasks to prevent changes... + */ + spin_lock(&clnt->cl_lock); + list_for_each_entry(task, &clnt->cl_tasks, tk_task) { + if (!RPC_IS_ACTIVATED(task)) + continue; + if (!fnmatch(task, data)) + continue; + rpc_task_try_cancel(task, error); + count++; + } + spin_unlock(&clnt->cl_lock); + return count; +} +EXPORT_SYMBOL_GPL(rpc_cancel_tasks); + /* * Properly shut down an RPC client, terminating all outstanding * requests. diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index f388bfaf6ff0..de912e02371b 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -872,6 +872,17 @@ void rpc_signal_task(struct rpc_task *task) rpc_wake_up_queued_task(queue, task); } +void rpc_task_try_cancel(struct rpc_task *task, int error) +{ + struct rpc_wait_queue *queue; + + if (!rpc_task_set_rpc_status(task, error)) + return; + queue = READ_ONCE(task->tk_waitqueue); + if (queue) + rpc_wake_up_queued_task(queue, task); +} + void rpc_exit(struct rpc_task *task, int status) { task->tk_status = status; -- cgit v1.2.3