From: Petr Mladek <pmladek@suse.com>
To: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org,
Jason Wessel <jason.wessel@windriver.com>,
Daniel Thompson <daniel.thompson@linaro.org>,
Douglas Anderson <dianders@chromium.org>,
Aaron Tomlin <atomlin@redhat.com>,
Luis Chamberlain <mcgrof@kernel.org>,
kgdb-bugreport@lists.sourceforge.net,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
"Guilherme G. Piccoli" <gpiccoli@igalia.com>,
David Gow <davidgow@google.com>,
Tiezhu Yang <yangtiezhu@loongson.cn>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
tangmeng <tangmeng@uniontech.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
rcu@vger.kernel.org
Subject: Re: locking API: was: [PATCH printk v1 00/18] serial: 8250: implement non-BKL console
Date: Wed, 29 Mar 2023 10:03:34 +0200 [thread overview]
Message-ID: <ZCPw1pEakE7SGsKg@alley> (raw)
In-Reply-To: <87ilekmtuj.fsf@jogness.linutronix.de>
On Tue 2023-03-28 23:53:16, John Ogness wrote:
> On 2023-03-28, Petr Mladek <pmladek@suse.com> wrote:
> >> If an atomic context loses ownership while doing certain activities,
> >> it may need to re-acquire ownership in order to finish or cleanup
> >> what it started.
> >
> > This sounds suspicious. If a console/writer context has lost the lock
> > then all shared/locked resources might already be used by the new
> > owner.
>
> Correct.
>
> > I would expect that the context could touch only non-shared resources
> > after loosing the lock.
>
> Correct.
>
> The 8250 driver must disable interrupts before writing to the TX
> FIFO. After writing it re-enables the interrupts. However, it might be
> the case that the interrupts were already disabled, in which case after
> writing they are left disabled.
I see. The reacquire() makes sense now.
Thanks a lot for explanation.
Best Regards,
Petr
next prev parent reply other threads:[~2023-03-29 8:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-02 19:56 [PATCH printk v1 00/18] threaded/atomic console support John Ogness
2023-03-02 19:56 ` [PATCH printk v1 17/18] rcu: Add atomic write enforcement for rcu stalls John Ogness
2023-04-13 12:10 ` Petr Mladek
2023-03-02 19:58 ` [PATCH printk v1 00/18] serial: 8250: implement non-BKL console John Ogness
2023-03-28 13:33 ` locking API: was: " Petr Mladek
2023-03-28 13:57 ` John Ogness
2023-03-28 15:10 ` Petr Mladek
2023-03-28 21:47 ` John Ogness
2023-03-29 8:03 ` Petr Mladek [this message]
2023-03-28 13:59 ` [PATCH printk v1 00/18] POC: serial: 8250: implement nbcon console John Ogness
2023-03-09 10:55 ` [PATCH printk v1 00/18] threaded/atomic console support Daniel Thompson
2023-03-09 11:14 ` John Ogness
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