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Message-Id: <20211117163050.53986-4-mark.rutland@arm.com>
Date: Wed, 17 Nov 2021 16:30:41 +0000
From: Mark Rutland <mark.rutland@....com>
To: linux-kernel@...r.kernel.org
Cc: benh@...nel.crashing.org, boqun.feng@...il.com, bp@...en8.de,
catalin.marinas@....com, dvyukov@...gle.com, efuller@...hat.com,
elver@...gle.com, ink@...assic.park.msu.ru, joey.gouly@....com,
jonas@...thpole.se, juri.lelli@...hat.com, linux@...linux.org.uk,
luto@...nel.org, mark.rutland@....com, mattst88@...il.com,
michal.simek@...inx.com, mingo@...hat.com, mpe@...erman.id.au,
npiggin@...il.com, paulmck@...nel.org, paulus@...ba.org,
peterz@...radead.org, rth@...ddle.net, shorne@...il.com,
stefan.kristiansson@...nalahti.fi, tglx@...utronix.de,
vincent.guittot@...aro.org, will@...nel.org
Subject: [PATCHv7 03/11] sched: snapshot thread flags
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 <mark.rutland@....com>
Acked-by: Paul E. McKenney <paulmck@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
---
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 3c9b0fda64ac..7ba05dedaf5b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8520,7 +8520,7 @@ 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
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