From: Jens Axboe axboe@kernel.dk
[ Upstream commit c7aab1a7c52b82d9afd7e03c398eb03dc2aa0507 ]
The only exported helper we have right now is task_work_cancel(), which cancels any task_work from a given task where func matches the queued work item. This is a bit too coarse for some use cases. Add a task_work_cancel_match() that allows to more specifically target individual work items outside of purely the callback function used.
task_work_cancel() can be trivially implemented on top of that, hence do so.
Reviewed-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/task_work.h | 2 ++ kernel/task_work.c | 35 ++++++++++++++++++++++++++++------- 2 files changed, 30 insertions(+), 7 deletions(-)
--- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -22,6 +22,8 @@ enum task_work_notify_mode { int task_work_add(struct task_struct *task, struct callback_head *twork, enum task_work_notify_mode mode);
+struct callback_head *task_work_cancel_match(struct task_struct *task, + bool (*match)(struct callback_head *, void *data), void *data); struct callback_head *task_work_cancel(struct task_struct *, task_work_func_t); void task_work_run(void);
--- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -59,18 +59,17 @@ int task_work_add(struct task_struct *ta }
/** - * task_work_cancel - cancel a pending work added by task_work_add() + * task_work_cancel_match - cancel a pending work added by task_work_add() * @task: the task which should execute the work - * @func: identifies the work to remove - * - * Find the last queued pending work with ->func == @func and remove - * it from queue. + * @match: match function to call * * RETURNS: * The found work or NULL if not found. */ struct callback_head * -task_work_cancel(struct task_struct *task, task_work_func_t func) +task_work_cancel_match(struct task_struct *task, + bool (*match)(struct callback_head *, void *data), + void *data) { struct callback_head **pprev = &task->task_works; struct callback_head *work; @@ -86,7 +85,7 @@ task_work_cancel(struct task_struct *tas */ raw_spin_lock_irqsave(&task->pi_lock, flags); while ((work = READ_ONCE(*pprev))) { - if (work->func != func) + if (!match(work, data)) pprev = &work->next; else if (cmpxchg(pprev, work, work->next) == work) break; @@ -96,6 +95,28 @@ task_work_cancel(struct task_struct *tas return work; }
+static bool task_work_func_match(struct callback_head *cb, void *data) +{ + return cb->func == data; +} + +/** + * task_work_cancel - cancel a pending work added by task_work_add() + * @task: the task which should execute the work + * @func: identifies the work to remove + * + * Find the last queued pending work with ->func == @func and remove + * it from queue. + * + * RETURNS: + * The found work or NULL if not found. + */ +struct callback_head * +task_work_cancel(struct task_struct *task, task_work_func_t func) +{ + return task_work_cancel_match(task, task_work_func_match, func); +} + /** * task_work_run - execute the works added by task_work_add() *