task_work: add helper for more targeted task_work canceling

stable inclusion
from stable-v5.10.162
commit ed3005032993da7a3fe2e6095436e0bc2e83d011
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6BTWC
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.10.168&id=ed3005032993da7a3fe2e6095436e0bc2e83d011

--------------------------------

[ Upstream commit c7aab1a7 ]

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: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLi Lingfeng <lilingfeng3@huawei.com>
Acked-by: NZhang Yi <yi.zhang@huawei.com>
Reviewed-by: NWang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

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);
 

kernel/task_work.c

@@ -70,18 +70,17 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
 }
 
 /**
- * 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;
@@ -97,7 +96,7 @@ task_work_cancel(struct task_struct *task, task_work_func_t func)
 	 */
 	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;
@@ -107,6 +106,28 @@ task_work_cancel(struct task_struct *task, task_work_func_t func)
 	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()
  *