linux-kernel - Re: printk: what is going on with additional newlines?

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Message-ID: <1504060296.2786.8.camel@perches.com>
Date:   Tue, 29 Aug 2017 19:31:36 -0700
From:   Joe Perches <joe@...ches.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Pavel Machek <pavel@....cz>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Petr Mladek <pmladek@...e.com>, Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jiri Slaby <jslaby@...e.com>, Andreas Mohr <andi@...as.de>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: printk: what is going on with additional newlines?

On Wed, 2017-08-30 at 11:25 +0900, Sergey Senozhatsky wrote:
> On (08/29/17 18:52), Joe Perches wrote:
> [..]
> > > We could simply add a seq_buf_printk() that is implemented in the printk
> > > proper, to parse the seq_buf buffer properly, and add the timestamps and
> > > such.
> > 
> > No need.  printk would already add timestamps.
> 
> the idea is not to do printk() on that seq buffer at all, but to
> log_store(), atomically, seq buffer messages
> 
> 	spin_lock(&logbuf_lock)
> 	while (offset < seq_buffer->len) {
> 		...
> 		log_store(seq->buffer + offset);
> 		...
> 	}
> 	spin_unlock(&logbuf_unlock)

Why?

What's wrong with a simple printk?
It'd still do a log_store.