linux-kernel - Re: [PATCH 4/8] pstore: Alert on backend write error

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Message-ID: <55cceaf8-acd4-22e2-61b5-99fff4ad5d75@igalia.com>
Date:   Thu, 6 Oct 2022 20:34:44 -0300
From:   "Guilherme G. Piccoli" <gpiccoli@...lia.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        kernel-dev@...lia.com, kernel@...ccoli.net, anton@...msg.org,
        ccross@...roid.com, tony.luck@...el.com
Subject: Re: [PATCH 4/8] pstore: Alert on backend write error

On 06/10/2022 20:27, Kees Cook wrote:
> [...]
>> --- a/fs/pstore/platform.c
>> +++ b/fs/pstore/platform.c
>> @@ -463,6 +463,9 @@ static void pstore_dump(struct kmsg_dumper *dumper,
>>  		if (ret == 0 && reason == KMSG_DUMP_OOPS) {
>>  			pstore_new_entry = 1;
>>  			pstore_timer_kick();
>> +		} else {
>> +			pr_err_once("backend (%s) writing error (%d)\n",
>> +				    psinfo->name, ret);
> 
> We're holding a spinlock here, so doing a pr_*() call isn't a great
> idea. It's kind of not a great idea to try to write to the log in the
> middle of a dump either, but we do attempt it at the start.
> 
> Perhaps keep a saved_ret or something and send it after the spin lock is
> released?
> 

Hi Kees, thanks a lot for the very quick review!!

Agree with you, I'll rework this one.
Do you agree with showing only a single error? For me makes sense since
we just wanna hint advanced users (+ people-debugging-pstore heh) that
something went wrong.

Cheers,


Guilherme