2023-02-28 16:14:48

by Uros Bizjak

Subject: [PATCH] sched/core: Use do-while instead of for loop in set_nr_if_polling

Use equivalent do-while loop instead of infinite for loop.

There are no asm code changes.

Signed-off-by: Uros Bizjak <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: Dietmar Eggemann <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Ben Segall <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Christian Brauner <[email protected]>
---
kernel/sched/core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index af017e038b48..349c018eaf09 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -899,14 +899,13 @@ static bool set_nr_if_polling(struct task_struct *p)
struct thread_info *ti = task_thread_info(p);
typeof(ti->flags) val = READ_ONCE(ti->flags);

- for (;;) {
+ do {
if (!(val & _TIF_POLLING_NRFLAG))
return false;
if (val & _TIF_NEED_RESCHED)
return true;
- if (try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED))
- break;
- }
+ } while (!try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED));
+
return true;
}

--
2.39.2

2023-04-04 06:12:51

by Uros Bizjak

Subject: Re: [PATCH] sched/core: Use do-while instead of for loop in set_nr_if_polling

I would like to ping for the patch below. The patch normalizes
try_cmpxchg loop to a more readable "while" instead of "for (;;)"
loop, otherwise it is a nop.

https://lore.kernel.org/lkml/[email protected]/

Uros.



On Tue, Feb 28, 2023 at 5:14 PM Uros Bizjak <[email protected]> wrote:
>
> Use equivalent do-while loop instead of infinite for loop.
>
> There are no asm code changes.
>
> Signed-off-by: Uros Bizjak <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Juri Lelli <[email protected]>
> Cc: Vincent Guittot <[email protected]>
> Cc: Dietmar Eggemann <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> Cc: Ben Segall <[email protected]>
> Cc: Mel Gorman <[email protected]>
> Cc: Daniel Bristot de Oliveira <[email protected]>
> Cc: Christian Brauner <[email protected]>
> ---
> kernel/sched/core.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index af017e038b48..349c018eaf09 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -899,14 +899,13 @@ static bool set_nr_if_polling(struct task_struct *p)
> struct thread_info *ti = task_thread_info(p);
> typeof(ti->flags) val = READ_ONCE(ti->flags);
>
> - for (;;) {
> + do {
> if (!(val & _TIF_POLLING_NRFLAG))
> return false;
> if (val & _TIF_NEED_RESCHED)
> return true;
> - if (try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED))
> - break;
> - }
> + } while (!try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED));
> +
> return true;
> }
>
> --
> 2.39.2
>

2023-09-15 18:02:55

by tip-bot2 for Alexey Makhalov

Subject: [tip: sched/core] sched/core: Use do-while instead of for loop in set_nr_if_polling()

The following commit has been merged into the sched/core branch of tip:

Commit-ID: 4ff34ad3d39377d9f6953f3606ccf611ce636767
Gitweb: https://git.kernel.org/tip/4ff34ad3d39377d9f6953f3606ccf611ce636767
Author: Uros Bizjak <[email protected]>
AuthorDate: Tue, 28 Feb 2023 17:14:26 +01:00
Committer: Ingo Molnar <[email protected]>
CommitterDate: Fri, 15 Sep 2023 17:18:02 +02:00

sched/core: Use do-while instead of for loop in set_nr_if_polling()

Use equivalent do-while loop instead of infinite for loop.

There are no asm code changes.

Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
kernel/sched/core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 76662d8..f39482d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -919,14 +919,13 @@ static bool set_nr_if_polling(struct task_struct *p)
struct thread_info *ti = task_thread_info(p);
typeof(ti->flags) val = READ_ONCE(ti->flags);

- for (;;) {
+ do {
if (!(val & _TIF_POLLING_NRFLAG))
return false;
if (val & _TIF_NEED_RESCHED)
return true;
- if (try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED))
- break;
- }
+ } while (!try_cmpxchg(&ti->flags, &val, val | _TIF_NEED_RESCHED));
+
return true;
}