linux-kernel - Re: [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback from console code

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Message-ID: <20180504153717.4806d9c4@roar.ozlabs.ibm.com>
Date:   Fri, 4 May 2018 15:37:17 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev@...ts.ozlabs.org, Jiri Slaby <jslaby@...e.com>,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback
 from console code

On Fri, 04 May 2018 15:16:37 +1000
Michael Ellerman <mpe@...erman.id.au> wrote:

> Nicholas Piggin <npiggin@...il.com> writes:
> 
> > Use the more refined and tested event polling loop from opal_put_chars
> > as the fallback console flush in the opal-kmsg path. This loop is used
> > by the console driver today, whereas the opal-kmsg fallback is not
> > likely to have been used for years.
> >
> > Use WARN_ONCE rather than a printk when the fallback is invoked to
> > prepare for moving the console flush into a common function.  
> 
> Do we want to add a WARN in that path? If we're panicking things might
> get worse if we WARN (which takes a trap).

True, probably a good idea not to... oh there's a printk_once so
that'll work nicely.

Thanks,
Nick