From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D29DDC433F5 for ; Tue, 14 Sep 2021 10:31:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BA05160F21 for ; Tue, 14 Sep 2021 10:31:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231837AbhINKcT (ORCPT ); Tue, 14 Sep 2021 06:32:19 -0400 Received: from foss.arm.com ([217.140.110.172]:42824 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231264AbhINKcL (ORCPT ); Tue, 14 Sep 2021 06:32:11 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BCDD51063; Tue, 14 Sep 2021 03:30:54 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id AB5A73F59C; Tue, 14 Sep 2021 03:30:51 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: benh@kernel.crashing.org, boqun.feng@gmail.com, bp@alien8.de, catalin.marinas@arm.com, dvyukov@google.com, elver@google.com, ink@jurassic.park.msu.ru, jonas@southpole.se, juri.lelli@redhat.com, linux@armlinux.org.uk, luto@kernel.org, mark.rutland@arm.com, mattst88@gmail.com, michal.simek@xilinx.com, mingo@redhat.com, mpe@ellerman.id.au, paulmck@kernel.org, paulus@samba.org, peterz@infradead.org, rth@twiddle.net, shorne@gmail.com, stefan.kristiansson@saunalahti.fi, tglx@linutronix.de, vincent.guittot@linaro.org, will@kernel.org Subject: [PATCH v5 03/10] sched: snapshot thread flags Date: Tue, 14 Sep 2021 11:30:20 +0100 Message-Id: <20210914103027.53565-4-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210914103027.53565-1-mark.rutland@arm.com> References: <20210914103027.53565-1-mark.rutland@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. The READ_ONCE(ti->flags) .. cmpxchg(ti->flags) loop in set_nr_if_polling() is left as-is for clarity. Signed-off-by: Mark Rutland Acked-by: Paul E. McKenney Cc: Ingo Molnar Cc: Juri Lelli Cc: Peter Zijlstra Cc: Vincent Guittot --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1bba4128a3e6..b65876b5d64c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8538,7 +8538,7 @@ void sched_show_task(struct task_struct *p) rcu_read_unlock(); pr_cont(" stack:%5lu pid:%5d ppid:%6d flags:0x%08lx\n", free, task_pid_nr(p), ppid, - (unsigned long)task_thread_info(p)->flags); + read_task_thread_flags(p)); print_worker_info(KERN_INFO, p); print_stop_info(KERN_INFO, p); -- 2.11.0