From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH printk v2 2/5] printk: Add NMI safety to console_flush_on_panic() and console_unblank()
Date: Fri, 14 Jul 2023 13:00:49 +0900 [thread overview]
Message-ID: <20230714040049.GA81525@google.com> (raw)
In-Reply-To: <ZLANiK_1YoBu1YpU@alley>
On (23/07/13 16:43), Petr Mladek wrote:
>
> Simple removal of console_trylock() in console_flush_on_panic() would
> cause that other CPUs might still be able to take it and race.
> The problem is avoided by checking panic_in_progress() in console_lock()
> and console_trylock(). They will never succeed on non-panic CPUs.
>
In theory, we also can have non-panic CPU in console_flush_all(),
which should let panic CPU to take over the next time it checks
abandon_console_lock_in_panic() (other_cpu_in_panic() after 5/5),
but it may not happen immediately. I wonder if we somehow can/want
to "wait" in console_flush_on_panic() for non-panic CPU handover?
next prev parent reply other threads:[~2023-07-14 4:01 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-10 13:45 [PATCH printk v2 0/5] various cleanups John Ogness
2023-07-10 13:45 ` [PATCH printk v2 1/5] kdb: do not assume write() callback available John Ogness
2023-07-11 0:25 ` Sergey Senozhatsky
2023-07-11 8:23 ` Daniel Thompson
2023-07-11 8:58 ` John Ogness
2023-07-11 9:01 ` Daniel Thompson
2023-07-10 13:45 ` [PATCH printk v2 2/5] printk: Add NMI safety to console_flush_on_panic() and console_unblank() John Ogness
2023-07-11 15:43 ` Petr Mladek
2023-07-11 16:07 ` Sergey Senozhatsky
2023-07-12 21:11 ` John Ogness
2023-07-13 14:43 ` Petr Mladek
2023-07-14 4:00 ` Sergey Senozhatsky [this message]
2023-07-14 9:41 ` Petr Mladek
2023-07-10 13:45 ` [PATCH printk v2 3/5] printk: Consolidate console deferred printing John Ogness
2023-07-11 15:17 ` Sergey Senozhatsky
2023-07-13 14:51 ` Petr Mladek
2023-07-10 13:45 ` [PATCH printk v2 4/5] printk: Add per-console suspended state John Ogness
2023-07-11 15:08 ` Sergey Senozhatsky
2023-07-11 15:23 ` John Ogness
2023-07-11 15:26 ` Sergey Senozhatsky
2023-07-11 15:30 ` Sergey Senozhatsky
2023-07-13 15:53 ` Petr Mladek
2023-07-10 13:45 ` [PATCH printk v2 5/5] printk: Rename abandon_console_lock_in_panic() to other_cpu_in_panic() John Ogness
2023-07-11 0:22 ` Sergey Senozhatsky
2023-07-13 15:55 ` Petr Mladek
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