From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Petr Mladek <pmladek@suse.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org,
Stephen Rothwell <sfr@canb.auug.org.au>,
Andrew Morton <akpm@linux-foundation.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Stephen Boyd <swboyd@chromium.org>,
Alexander Potapenko <glider@google.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH next v3 1/2] dump_stack: move cpu lock to printk.c
Date: Wed, 16 Jun 2021 20:55:33 +0900 [thread overview]
Message-ID: <YMnmtXG4WE9/xp8f@google.com> (raw)
In-Reply-To: <87mtrqnu74.fsf@jogness.linutronix.de>
On (21/06/16 09:35), John Ogness wrote:
> It isn't about limiting. It is about tracking.
Oh, yes. I missed it.
>
[..]
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index e67dc510fa1b..5376216e4f3d 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -3535,7 +3535,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
>
> #ifdef CONFIG_SMP
> static atomic_t printk_cpulock_owner = ATOMIC_INIT(-1);
> -static bool printk_cpulock_nested;
> +static atomic_t printk_cpulock_nested = ATOMIC_INIT(0);
>
> /**
> * __printk_wait_on_cpu_lock() - Busy wait until the printk cpu-reentrant
> @@ -3596,7 +3598,7 @@ int __printk_cpu_trylock(void)
>
> } else if (old == cpu) {
> /* This CPU is already the owner. */
> - printk_cpulock_nested = true;
> + atomic_inc(&printk_cpulock_nested);
> return 1;
> }
>
> @@ -3613,8 +3615,8 @@ EXPORT_SYMBOL(__printk_cpu_trylock);
> */
> void __printk_cpu_unlock(void)
> {
> - if (printk_cpulock_nested) {
> - printk_cpulock_nested = false;
> + if (atomic_read(&printk_cpulock_nested)) {
> + atomic_dec(&printk_cpulock_nested);
> return;
> }
Looks good.
next prev parent reply other threads:[~2021-06-16 11:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 17:49 [PATCH next v3 0/2] introduce printk cpu lock John Ogness
2021-06-15 17:49 ` [PATCH next v3 1/2] dump_stack: move cpu lock to printk.c John Ogness
2021-06-15 21:33 ` John Ogness
2021-06-16 7:06 ` Sergey Senozhatsky
2021-06-16 7:29 ` John Ogness
2021-06-16 11:21 ` Petr Mladek
2021-06-16 13:40 ` John Ogness
2021-06-16 11:55 ` Sergey Senozhatsky [this message]
2021-06-15 17:49 ` [PATCH next v3 2/2] printk: fix cpu lock ordering John Ogness
2021-06-16 11:30 ` Petr Mladek
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