From: Petr Mladek <pmladek@suse.com>
To: John Ogness <john.ogness@linutronix.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH printk 3/5] printk: use buffer pool for sprint buffers
Date: Wed, 23 Sep 2020 17:11:29 +0200 [thread overview]
Message-ID: <20200923151129.GC6442@alley> (raw)
In-Reply-To: <20200922153816.5883-4-john.ogness@linutronix.de>
On Tue 2020-09-22 17:44:14, John Ogness wrote:
> vprintk_store() is using a single static buffer as a temporary
> sprint buffer for the message text. This will not work once
> @logbuf_lock is removed. Replace the single static buffer with a
> pool of buffers.
The buffer is used because we do not know the length of the
formatted message to reserve the right space in the ring buffer
in advance.
There was the idea to call vsprintf(NULL, fmt, args) to count
the length in advance.
AFAIK, there is one catch. We need to use va_copy() around
the 1st call because va_format can be proceed only once.
See, va_format() in lib/vsprintf.c as an example.
Is there any other problem, please?
Best Regards,
Petr
next prev parent reply other threads:[~2020-09-23 15:11 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 15:38 [PATCH printk 0/5] printk: remove logbuf_lock John Ogness
2020-09-22 15:38 ` [PATCH printk 1/5] printk: get new seq before enabling interrupts John Ogness
2020-09-23 14:17 ` Petr Mladek
2020-09-23 14:36 ` John Ogness
2020-09-22 15:38 ` [PATCH printk 2/5] printk: kmsg_dump_rewind_nolock: start from first record John Ogness
2020-09-23 14:52 ` Petr Mladek
2020-09-23 15:39 ` John Ogness
2020-09-22 15:38 ` [PATCH printk 3/5] printk: use buffer pool for sprint buffers John Ogness
2020-09-23 15:11 ` Petr Mladek [this message]
2020-09-23 15:21 ` David Laight
2020-09-23 16:41 ` Petr Mladek
2020-09-24 5:40 ` Sergey Senozhatsky
2020-09-24 8:45 ` Petr Mladek
2020-09-24 8:53 ` Sergey Senozhatsky
2020-09-24 9:49 ` Rasmus Villemoes
2020-09-25 8:15 ` Petr Mladek
2020-09-24 9:54 ` Rasmus Villemoes
2020-09-24 12:32 ` Rasmus Villemoes
2020-09-25 8:28 ` Petr Mladek
2020-09-30 8:06 ` Rasmus Villemoes
2020-09-30 8:51 ` Petr Mladek
2020-09-30 8:57 ` John Ogness
2020-09-30 13:35 ` Steven Rostedt
2020-09-30 14:32 ` David Laight
2020-10-01 7:15 ` Rasmus Villemoes
2020-10-01 7:58 ` Petr Mladek
2020-09-24 1:21 ` Sergey Senozhatsky
2020-09-24 6:17 ` Sergey Senozhatsky
2020-09-24 8:54 ` Petr Mladek
2020-09-24 9:06 ` Sergey Senozhatsky
2020-09-25 8:13 ` Petr Mladek
2020-09-22 15:38 ` [PATCH printk 4/5] printk: remove logbuf_lock, add syslog_lock John Ogness
2020-09-23 16:30 ` Petr Mladek
2020-09-24 8:45 ` Sergey Senozhatsky
2020-09-24 9:21 ` John Ogness
2020-09-22 15:38 ` [PATCH printk 5/5] printk: remove nmi safe buffers John Ogness
2020-09-23 16:36 ` Petr Mladek
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