From: John Ogness <john.ogness@linutronix.de>
To: Breno Leitao <leitao@debian.org>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mike Galbraith <efault@gmx.de>,
linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH printk v1 1/1] printk: nbcon: Allow unsafe write_atomic() for panic
Date: Mon, 15 Sep 2025 21:15:46 +0206 [thread overview]
Message-ID: <845xdj8rd1.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <i6qgd5wcdl5gkwfc6cru2hnokcsawdd4yzez2i6klu54uxwx23@jl44kdpph3t3>
On 2025-09-15, Breno Leitao <leitao@debian.org> wrote:
> If there is a printk() inside an IRQ and the host is not panicking, then
> the message will be deferred to the kthread, which will print through
> ->write_thread.
>
> So, from a user/netconsole perspective, assuming the no panic
> (allow_unsafe_takeover=false) all the messages will be transmitted
> (always from a thread context), even if the printk() happens on an IRQ.
> So, no message will be lost.
>
> Is my understanding right?
Yes. So you will always have a safe context to write from (except in
panic, where you will do your unsafe code).
John
next prev parent reply other threads:[~2025-09-15 19:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-12 12:18 [PATCH printk v1 0/1] Allow unsafe ->write_atomic() for panic John Ogness
2025-09-12 12:18 ` [PATCH printk v1 1/1] printk: nbcon: Allow unsafe write_atomic() " John Ogness
2025-09-15 14:01 ` Breno Leitao
2025-09-15 14:14 ` John Ogness
2025-09-15 15:46 ` Breno Leitao
2025-09-15 19:09 ` John Ogness [this message]
2025-09-16 13:25 ` Petr Mladek
2025-09-16 15:05 ` Petr Mladek
2025-09-17 12:47 ` John Ogness
2025-09-17 13:51 ` Petr Mladek
2025-09-22 10:44 ` John Ogness
2025-09-22 11:45 ` Petr Mladek
2025-09-23 12:30 ` Breno Leitao
2025-09-17 14:44 ` [PATCH printk v1 0/1] Allow unsafe ->write_atomic() " Breno Leitao
2025-09-26 9:21 ` John Ogness
2025-09-26 15:17 ` Breno Leitao
2025-09-29 12:18 ` Petr Mladek
2025-09-29 13:36 ` John Ogness
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