linux-kernel - Re: [RFC][PATCH 1/2] printk: lock console_sem before we unregister boot consoles

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Message-ID: <20190425075606.GA16917@jagdpanzerIV>
Date:   Thu, 25 Apr 2019 16:56:06 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [RFC][PATCH 1/2] printk: lock console_sem before we unregister
 boot consoles

On (04/25/19 09:50), Petr Mladek wrote:
> > Sure we can.
> > 
> > We also can take extra care of pr_info("%sconsole [%s%d] enabled\n".
> > Right now we do
> > 
> > 	...
> > 	console_unlock();
> > 	console_sysfs_notify();
> > 
> > 	pr_info("%sconsole [%s%d] enabled\n",....
> > 
> > 
> > But we can simply move that pr_info() a bit up:
> > 
> > 	pr_info("%sconsole [%s%d] enabled\n",
> > 	console_unlock();
> > 	console_sysfs_notify();
> > 
> > 
> > So the message will be printed on all consoles.
> 
> Great idea!
> 
> It would deserve a separate patch that moves the pr_info()
> and removes the invalid comment.
> 
> Actually, the pr_info() would deserve a comment explaining
> why it should be called before console_unlock().

Good. So I think I'll drop patch #1 from the series, add
two more patches - invalid comment + pr_info() - and rework
locking in patch #3 (this should take care of a race which
patch #1 was intended to fix).

	-ss