Commit 7f62d40d authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

task_work: Introduce task_work_pending 



Wrap the test of task->task_works in a helper function to make
it clear what is being tested.

All of the other readers of task->task_work use READ_ONCE and this is
even necessary on current as other processes can update
task->task_work.  So for consistency I have added READ_ONCE into
task_work_pending.

Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-7-ebiederm@xmission.com


Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 8ca07e17

fs/io_uring.c

+3 −3
Original line number Diff line number Diff line
@@ -2590,7 +2590,7 @@ static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx) 


static inline bool io_run_task_work(void)

{

	if (test_thread_flag(TIF_NOTIFY_SIGNAL) || current->task_works) {

	if (test_thread_flag(TIF_NOTIFY_SIGNAL) || task_work_pending(current)) {

		__set_current_state(TASK_RUNNING);

		tracehook_notify_signal();

		return true;
@@ -7602,7 +7602,7 @@ static int io_sq_thread(void *data) 
		}



		prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);

		if (!io_sqd_events_pending(sqd) && !current->task_works) {

		if (!io_sqd_events_pending(sqd) && !task_work_pending(current)) {

			bool needs_sched = true;



			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
@@ -10321,7 +10321,7 @@ static __cold void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, 


		hlist_for_each_entry(req, list, hash_node)

			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,

					req->task->task_works != NULL);

					task_work_pending(req->task));

	}



	seq_puts(m, "CqOverflowList:\n");

include/linux/task_work.h

+5 −0
Original line number Diff line number Diff line
@@ -19,6 +19,11 @@ enum task_work_notify_mode { 
	TWA_SIGNAL,

};



static inline bool task_work_pending(struct task_struct *task)

{

	return READ_ONCE(task->task_works);

}



int task_work_add(struct task_struct *task, struct callback_head *twork,

			enum task_work_notify_mode mode);

include/linux/tracehook.h

+2 −2
Original line number Diff line number Diff line
@@ -90,7 +90,7 @@ static inline void tracehook_notify_resume(struct pt_regs *regs) 
	 * hlist_add_head(task->task_works);

	 */

	smp_mb__after_atomic();

	if (unlikely(current->task_works))

	if (unlikely(task_work_pending(current)))

		task_work_run();



#ifdef CONFIG_KEYS_REQUEST_CACHE
@@ -115,7 +115,7 @@ static inline void tracehook_notify_signal(void) 
{

	clear_thread_flag(TIF_NOTIFY_SIGNAL);

	smp_mb__after_atomic();

	if (current->task_works)

	if (task_work_pending(current))

		task_work_run();

}

kernel/signal.c

+2 −2
Original line number Diff line number Diff line
@@ -2344,7 +2344,7 @@ static void ptrace_do_notify(int signr, int exit_code, int why) 
void ptrace_notify(int exit_code)

{

	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);

	if (unlikely(current->task_works))

	if (unlikely(task_work_pending(current)))

		task_work_run();



	spin_lock_irq(&current->sighand->siglock);
@@ -2626,7 +2626,7 @@ bool get_signal(struct ksignal *ksig) 
	struct signal_struct *signal = current->signal;

	int signr;



	if (unlikely(current->task_works))

	if (unlikely(task_work_pending(current)))

		task_work_run();



	/*

kernel/task_work.c

+1 −1
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ task_work_cancel_match(struct task_struct *task, 
	struct callback_head *work;

	unsigned long flags;



	if (likely(!task->task_works))

	if (likely(!task_work_pending(task)))

		return NULL;

	/*

	 * If cmpxchg() fails we continue without updating pprev.