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
Subject: Re: [PATCH printk v4 6/6] printk: syslog: close window between wait and read
Date: Wed, 21 Jul 2021 14:43:19 +0200 [thread overview]
Message-ID: <20210721124319.hy5rrn6p2i2r2qya@pathway.suse.cz> (raw)
In-Reply-To: <20210715193359.25946-7-john.ogness@linutronix.de>
On Thu 2021-07-15 21:39:59, John Ogness wrote:
> Syslog's SYSLOG_ACTION_READ is supposed to block until the next
> syslog record can be read, and then it should read that record.
> However, because @syslog_lock is not held between waking up and
> reading the record, another reader could read the record first,
> thus causing SYSLOG_ACTION_READ to return with a value of 0, never
> having read _anything_.
>
> By holding @syslog_lock between waking up and reading, it can be
> guaranteed that SYSLOG_ACTION_READ blocks until it successfully
> reads a syslog record (or a real error occurs).
>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
next prev parent reply other threads:[~2021-07-21 12:43 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-15 19:33 [PATCH printk v4 0/6] printk: remove safe buffers John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-15 19:33 ` [PATCH printk v4 1/6] lib/nmi_backtrace: explicitly serialize banner and regs John Ogness
2021-07-15 19:33 ` [PATCH printk v4 2/6] printk: track/limit recursion John Ogness
2021-07-15 19:33 ` [PATCH printk v4 3/6] printk: remove safe buffers John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-21 11:25 ` Petr Mladek
2021-07-21 11:25 ` Petr Mladek
2021-07-21 11:25 ` Petr Mladek
2021-09-02 16:48 ` Geert Uytterhoeven
2021-09-02 16:48 ` Geert Uytterhoeven
2021-09-02 16:48 ` Geert Uytterhoeven
2021-07-15 19:33 ` [PATCH printk v4 4/6] printk: remove NMI tracking John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-15 19:33 ` John Ogness
2021-07-21 12:00 ` Petr Mladek
2021-07-21 12:00 ` Petr Mladek
2021-07-21 12:00 ` Petr Mladek
2021-07-21 12:46 ` John Ogness
2021-07-21 12:46 ` John Ogness
2021-07-21 12:46 ` John Ogness
2021-07-21 13:08 ` Petr Mladek
2021-07-21 13:08 ` Petr Mladek
2021-07-21 13:08 ` Petr Mladek
2021-07-21 13:23 ` John Ogness
2021-07-21 13:23 ` John Ogness
2021-07-21 13:23 ` John Ogness
2021-07-15 19:33 ` [PATCH printk v4 5/6] printk: convert @syslog_lock to mutex John Ogness
2021-07-21 12:21 ` Petr Mladek
2021-07-15 19:33 ` [PATCH printk v4 6/6] printk: syslog: close window between wait and read John Ogness
2021-07-21 12:43 ` Petr Mladek [this message]
2021-07-27 7:26 ` [PATCH printk v4 0/6] printk: remove safe buffers Petr Mladek
2021-07-27 7:26 ` Petr Mladek
2021-07-27 7:26 ` Petr Mladek
2021-07-27 7:26 ` Petr Mladek
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