From: Mark Rutland Date: Mon, 29 Nov 2021 13:06:45 +0000 (+0000) Subject: sched: Snapshot thread flags X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0569b245132c40015281610353935a50e282eb94;p=linux.git 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 Signed-off-by: Thomas Gleixner Acked-by: Paul E. McKenney Cc: Juri Lelli Cc: Vincent Guittot Link: https://lore.kernel.org/r/20211129130653.2037928-4-mark.rutland@arm.com --- diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 76f9deeaa9420..704262798fb78 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);