diff options
| -rw-r--r-- | include/linux/sched/signal.h | 13 | ||||
| -rw-r--r-- | include/linux/task_work.h | 1 | ||||
| -rw-r--r-- | kernel/task_work.c | 25 |
3 files changed, 31 insertions, 8 deletions
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 3c8b34876744..66b689f6cfcb 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -356,13 +356,22 @@ static inline void clear_notify_signal(void) } /* + * Returns 'true' if kick_process() is needed to force a transition from + * user -> kernel to guarantee expedient run of TWA_SIGNAL based task_work. + */ +static inline bool __set_notify_signal(struct task_struct *task) +{ + return !test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) && + !wake_up_state(task, TASK_INTERRUPTIBLE); +} + +/* * Called to break out of interruptible wait loops, and enter the * exit_to_user_mode_loop(). */ static inline void set_notify_signal(struct task_struct *task) { - if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL) && - !wake_up_state(task, TASK_INTERRUPTIBLE)) + if (__set_notify_signal(task)) kick_process(task); } diff --git a/include/linux/task_work.h b/include/linux/task_work.h index 897494b597ba..795ef5a68429 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -17,6 +17,7 @@ enum task_work_notify_mode { TWA_NONE, TWA_RESUME, TWA_SIGNAL, + TWA_SIGNAL_NO_IPI, }; static inline bool task_work_pending(struct task_struct *task) diff --git a/kernel/task_work.c b/kernel/task_work.c index c59e1a49bc40..dff75bcde151 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -12,12 +12,22 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */ * @notify: how to notify the targeted task * * Queue @work for task_work_run() below and notify the @task if @notify - * is @TWA_RESUME or @TWA_SIGNAL. @TWA_SIGNAL works like signals, in that the - * it will interrupt the targeted task and run the task_work. @TWA_RESUME - * work is run only when the task exits the kernel and returns to user mode, - * or before entering guest mode. Fails if the @task is exiting/exited and thus - * it can't process this @work. Otherwise @work->func() will be called when the - * @task goes through one of the aforementioned transitions, or exits. + * is @TWA_RESUME, @TWA_SIGNAL, or @TWA_SIGNAL_NO_IPI. + * + * @TWA_SIGNAL works like signals, in that the it will interrupt the targeted + * task and run the task_work, regardless of whether the task is currently + * running in the kernel or userspace. + * @TWA_SIGNAL_NO_IPI works like @TWA_SIGNAL, except it doesn't send a + * reschedule IPI to force the targeted task to reschedule and run task_work. + * This can be advantageous if there's no strict requirement that the + * task_work be run as soon as possible, just whenever the task enters the + * kernel anyway. + * @TWA_RESUME work is run only when the task exits the kernel and returns to + * user mode, or before entering guest mode. + * + * Fails if the @task is exiting/exited and thus it can't process this @work. + * Otherwise @work->func() will be called when the @task goes through one of + * the aforementioned transitions, or exits. * * If the targeted task is exiting, then an error is returned and the work item * is not queued. It's up to the caller to arrange for an alternative mechanism @@ -53,6 +63,9 @@ int task_work_add(struct task_struct *task, struct callback_head *work, case TWA_SIGNAL: set_notify_signal(task); break; + case TWA_SIGNAL_NO_IPI: + __set_notify_signal(task); + break; default: WARN_ON_ONCE(1); break; |