All of lore.kernel.org
 help / color / mirror / Atom feed
From: Valentin Schneider <valentin.schneider@arm.com>
To: linux-kernel@vger.kernel.org
Cc: Yejune Deng <yejune.deng@gmail.com>,
	mingo@kernel.org, peterz@infradead.org, tglx@linutronix.de,
	bristot@redhat.com
Subject: [PATCH 2/2] lib/smp_processor_id: Use is_percpu_thread() instead of nr_cpus_allowed
Date: Mon, 10 May 2021 16:10:24 +0100	[thread overview]
Message-ID: <20210510151024.2448573-3-valentin.schneider@arm.com> (raw)
In-Reply-To: <20210510151024.2448573-1-valentin.schneider@arm.com>

From: Yejune Deng <yejune.deng@gmail.com>

is_percpu_thread() more elegantly handles SMP vs UP, and further checks the
presence of PF_NO_SETAFFINITY. This lets us catch cases where
check_preemption_disabled() can race with a concurrent sched_setaffinity().

Signed-off-by: Yejune Deng <yejune.deng@gmail.com>
[Amended changelog]
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
---
 lib/smp_processor_id.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 1c1dbd300325..046ac6297c78 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -19,11 +19,7 @@ unsigned int check_preemption_disabled(const char *what1, const char *what2)
 	if (irqs_disabled())
 		goto out;
 
-	/*
-	 * Kernel threads bound to a single CPU can safely use
-	 * smp_processor_id():
-	 */
-	if (current->nr_cpus_allowed == 1)
+	if (is_percpu_thread())
 		goto out;
 
 #ifdef CONFIG_SMP
-- 
2.25.1


  parent reply	other threads:[~2021-05-10 15:11 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-10 15:10 [PATCH 0/2] sched: Address idle task vs pcpu kthread checks Valentin Schneider
2021-05-10 15:10 ` [PATCH 1/2] sched: Make the idle task quack like a per-CPU kthread Valentin Schneider
2021-05-10 15:57   ` Valentin Schneider
2021-05-11  7:32     ` Ingo Molnar
2021-05-11  9:33       ` Valentin Schneider
2021-05-19  8:09   ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2021-05-10 15:10 ` Valentin Schneider [this message]
2021-05-19  8:09   ` [tip: sched/core] lib/smp_processor_id: Use is_percpu_thread() instead of nr_cpus_allowed tip-bot2 for Yejune Deng
2021-05-19  9:02   ` tip-bot2 for Yejune Deng
2021-05-31 10:21     ` [PATCH] sched,init: Fix DEBUG_PREEMPT vs early boot Peter Zijlstra
2021-06-01 11:54       ` Valentin Schneider
2021-06-01 14:04       ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-12 11:00 ` [PATCH 0/2] sched: Address idle task vs pcpu kthread checks Peter Zijlstra

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210510151024.2448573-3-valentin.schneider@arm.com \
    --to=valentin.schneider@arm.com \
    --cc=bristot@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=yejune.deng@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.