linux-kernel - Re: [PATCH v3 1/2] pstore: Avoid deadlock in panic and emergency-restart path

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Message-ID: <CA+8MBbKTHQJoeRVUGZr+rcXm+VwOw2vSG31Cwnrg-sc=CzLu9w@mail.gmail.com>
Date:	Thu, 10 Jan 2013 10:20:58 -0800
From:	Tony Luck <tony.luck@...il.com>
To:	Seiji Aguchi <seiji.aguchi@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dzickus@...hat.com" <dzickus@...hat.com>,
	"ccross@...roid.com" <ccross@...roid.com>,
	"keescook@...omium.org" <keescook@...omium.org>,
	"cbouatmailru@...il.com" <cbouatmailru@...il.com>,
	Satoru Moriya <satoru.moriya@....com>,
	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>
Subject: Re: [PATCH v3 1/2] pstore: Avoid deadlock in panic and
 emergency-restart path

On Thu, Dec 20, 2012 at 7:12 AM, Seiji Aguchi <seiji.aguchi@....com> wrote:
> +       if (pstore_cannot_block_path(reason)) {
> +               is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
> +               if (!is_locked) {
> +                       pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
> +                                      , in_nmi() ? "NMI" : why);
> +               }

My only quibble with this patchset is this message. The sentiment is
nice, but nobody will see it. kmsg_dump has already picked the
pieces of log_buf that will be saved to pstore - so this new message
won't be included.  I suppose it will show up on a serial console - but
if a user has a serial console, they don't need to use pstore.

But I don't think it is likely to hurt us (to get this far in a panic we already
printed a bunch of stuff to the console and I can't think of a credible
scenario where a few extra bytes would run into a problem that the
earlier messages didn't).

So:

Acked-by: Tony Luck <tony.luck@...el.com>

[Also Ack for part2 the touches efivars.c]

-Tony

[Or are you asking me to apply these rather than just Ack them??]
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