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Subject[PATCH 2/4] task_work: Introduce task_work_cancel() again
Date
Re-introduce task_work_cancel(), this time to cancel an actual callback
and not *any* callback pointing to a given function. This is going to be
needed for perf events event freeing.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
include/linux/task_work.h | 1 +
kernel/task_work.c | 24 ++++++++++++++++++++++++
2 files changed, 25 insertions(+)

diff --git a/include/linux/task_work.h b/include/linux/task_work.h
index 89ee2cbf044b..58e42ef59580 100644
--- a/include/linux/task_work.h
+++ b/include/linux/task_work.h
@@ -37,6 +37,7 @@ int task_work_add(struct task_struct *task, struct callback_head *twork,
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_func(struct task_struct *, task_work_func_t);
+bool task_work_cancel(struct task_struct *, struct callback_head *twork);
void task_work_run(void);

static inline void exit_task_work(struct task_struct *task)
diff --git a/kernel/task_work.c b/kernel/task_work.c
index c1b4d3ba2590..9e85ac7632ae 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -136,6 +136,30 @@ task_work_cancel_func(struct task_struct *task, task_work_func_t func)
return task_work_cancel_match(task, task_work_func_match, func);
}

+static bool task_work_match(struct callback_head *cb, void *data)
+{
+ return cb == data;
+}
+
+/**
+ * task_work_cancel - cancel a pending work added by task_work_add()
+ * @task: the task which should execute the work
+ * @func: the work to remove if queued
+ *
+ * Remove a callback from a task's queue if queued.
+ *
+ * RETURNS:
+ * True if the callback was queued and got cancelled, false otherwise.
+ */
+bool task_work_cancel(struct task_struct *task, struct callback_head *cb)
+{
+ struct callback_head *ret;
+
+ ret = task_work_cancel_match(task, task_work_match, cb);
+
+ return ret == cb;
+}
+
/**
* task_work_run - execute the works added by task_work_add()
*
--
2.44.0

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