From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Russell King <rmk+kernel@arm.linux.org.uk>,
Daniel Thompson <daniel.thompson@linaro.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Chris Metcalf <cmetcalf@ezchip.com>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH v2] printk: Use the main logbuf in NMI when logbuf_lock is available
Date: Fri, 5 May 2017 11:21:41 +0900 [thread overview]
Message-ID: <20170505022141.GA418@tigerII.localdomain> (raw)
In-Reply-To: <1493912763-24873-1-git-send-email-pmladek@suse.com>
On (05/04/17 17:46), Petr Mladek wrote:
[..]
> Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
a small nitpick,
[..]
> void printk_nmi_enter(void)
> {
> - this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
> + /*
> + * The size of the extra per-CPU buffer is limited. Use it only when
> + * the main one is locked. If this CPU is not in the safe context,
> + * the lock must be taken on another CPU and we could wait for it.
> + */
> + if (raw_spin_is_locked(&logbuf_lock) &&
> + this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK) {
> + this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
could we please check `printk_context' (local to a particular CPU)
first and, if positive, then access `logbuf_lock' (which is global)?
-ss
next prev parent reply other threads:[~2017-05-05 2:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-04 15:46 Petr Mladek
2017-05-05 2:21 ` Sergey Senozhatsky [this message]
2017-05-17 15:08 ` Petr Mladek
2017-05-19 2:58 ` Sergey Senozhatsky
2017-05-19 4:38 ` Sergey Senozhatsky
2017-05-19 13:02 ` Petr Mladek
2017-05-20 9:04 ` Sergey Senozhatsky
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