lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20180425132352.cs22ak5jzwr2f4v4@pathway.suse.cz>
Date:   Wed, 25 Apr 2018 15:23:52 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCHv2] printk: wake up klogd in vprintk_emit

On Fri 2018-04-20 10:52:21, Sergey Senozhatsky wrote:
> On (04/19/18 12:02), Petr Mladek wrote:
> > On Thu 2018-04-19 10:42:50, Sergey Senozhatsky wrote:
> > > We wake up klogd very late - only when current console_sem owner
> > > is done pushing pending kernel messages to the serial/net consoles.
> > > In some cases this results in lost syslog messages, because kernel
> > > log buffer is a circular buffer and if we don't wakeup syslog long
> > > enough there are chances that logbuf simply will wrap around.
> > > 
> > > The patch moves the klog wake up call to vprintk_emit(), which is
> > > the only legit way for a kernel message to appear in the logbuf,
> > > right before we attempt to grab the console_sem (possibly spinning
> > > on it waiting for the hand off) and call console drivers.
> > 
> > The last two lines need an update. What about?
> 
> Ah. Indeed!
> 
> > "right after the attempt to handle consoles. As a result, klog
> > will get waken either after flushing the new message to consoles
> > or immediately when consoles are still busy with older messages."
> 
> Looks good. Do you want me to resend the patch?

JFYI, I have updated the commit message and pushed the patch into
printk.git, for-4.18 branch.

Best Regards,
Petr

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ