linux-kernel - Re: [PATCH 1/2] ramoops: use pstore interface

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Date:	Thu, 17 Nov 2011 10:19:11 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Ben Gardner <bgardner@...tec.com>,
	Marco Stornelli <marco.stornelli@...il.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: Re: [PATCH 1/2] ramoops: use pstore interface

On Thu, Nov 17, 2011 at 7:07 AM, Arnd Bergmann <arnd@...db.de> wrote:
> On Wednesday 16 November 2011, Kees Cook wrote:
>> Instead of using /dev/mem directly, use the common pstore infrastructure
>> to handle Oops gathering and extraction.
>>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>
> Sounds like a very good plan to me. It probably makes sense to move the
> entire driver into fs/pstore after this. Otherwise, I have only trivial
> style comments:
>
>> +static int ramoops_pstore_open(struct pstore_info *psi);
>> +static int ramoops_pstore_close(struct pstore_info *psi);
>> +static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
>> +                                struct timespec *time,
>> +                                char **buf,
>> +                                struct pstore_info *psi);
>> +static int ramoops_pstore_write(enum pstore_type_id type,
>> +                             enum kmsg_dump_reason reason, u64 *id,
>> +                             unsigned int part,
>> +                             size_t size, struct pstore_info *psi);
>> +static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
>> +                             struct pstore_info *psi);
>
> Can you do it without forward declarations? Many people find code
> more readable if it is structure in the natural order that avoids
> these.

Actually, now that I look at it again, yeah, I can. When I did this
originally I hadn't noticed pstore_info.data. I'll use that to pass
cxt so I can avoid the forward declarations. Thanks!

>> +static int ramoops_pstore_close(struct pstore_info *psi)
>> +{
>> +     return 0;
>> +}
>
> Do you actually have to provide this if it's empty?

Yeah, though I suppose we could change pstore to DTRT in fs/pstore/platform.c:

        if (psi->close) psi->close(psi);

instead of the current:

        psi->close(psi);

> If yes, it might make sense to change the pstore code so that
> it works without a close function.

Yeah, I'll do that and send more patches. :)

Thanks!

-Kees

-- 
Kees Cook
ChromeOS Security
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