Messages in this thread | | | Date | Fri, 10 Jul 2009 16:07:49 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH,RFC,resend] printk: restore previous console_loglevel when re-enabling logging |
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* Frans Pop <elendil@planet.nl> wrote:
> When logging to console is disabled from userspace using klogctl() > and later re-enabled, console_loglevel gets set to the default > log level instead to the previous value. > This means that if the kernel was booted with 'quiet', the boot is > suddenly no longer quiet after logging to console gets re-enabled. > > Save the current console_loglevel when logging is disabled and > restore to that value. If the log level is set to a specific value > while disabled, this is interpreted as an implicit re-enabling of > the logging. > > Signed-off-by: Frans Pop <elendil@planet.nl> > --- > > Resend. The problem that prompted this patch is described in > http://lkml.org/lkml/2009/6/28/234 > > There are two variations possible on the patch below. > > 1) If klogctl(7) is called while logging is not disabled, then set level > to default (partially preserving current functionality): > case 7: /* Enable logging to console */ > - console_loglevel = default_console_loglevel; > + if (saved_console_loglevel == -1) > + console_loglevel = default_console_loglevel; > + else { > + console_loglevel = saved_console_loglevel; > + saved_console_loglevel = -1; > + } > > 2) If klogctl(8) is called while logging is disabled, then don't enable > logging, but remember the requested value for when logging does get > enabled again: > case 8: /* Set level of messages printed to console */ > [...] > - console_loglevel = len; > + if (saved_console_loglevel == -1) > + console_loglevel = len; > + else > + saved_console_loglevel = len; > > Yet another option would be to ignore the request.
Looks like a possible solution to a real problem (most distros today boot with quiet) - albeit it does change previous behavior so objections are possible on those grounds.
I've queued it up in the tip:core/printk tree and will push it out to linux-next in a few days if there are no objections.
Small sidenote: i moved the (somewhat obscurely placed) saved_console_loglevel static variable out of local variable scope and next to the console loglevel definitions (such as console_printk[]), to increase its visibility as globally relevant state and to move it next to the state this variable affects.
Thanks,
Ingo
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