linux-kernel - Re: [PATCH v3 1/2] init/do_mounts.c: ignore final \n in name_to_dev

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Message-Id: <20140128125442.4bac748945b404179deb58ba@linux-foundation.org>
Date:	Tue, 28 Jan 2014 12:54:42 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Sebastian Capella <sebastian.capella@...aro.org>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Pavel Machek" <pavel@....cz>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linaro-kernel@...ts.linaro.org, patches@...aro.org,
	"Serge Hallyn" <serge.hallyn@...onical.com>,
	"Stephen Warren" <swarren@...dia.com>,
	"Jens Axboe" <axboe@...nel.dk>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	"Al Viro" <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v3 1/2] init/do_mounts.c: ignore final \n in
 name_to_dev_t

On Tue, 28 Jan 2014 10:59:26 -0800 Sebastian Capella <sebastian.capella@...aro.org> wrote:

> > Do you have any feedback for me on this?
> > 
> > I'm happy do make any changes you think are correct, but I'm unsure if
> > you're asking me for option #3 above.  It's quite an intrusive change,
> > and changes old, established code and I'd like confirmation that's what
> > you'd like before proceeding down that path.
> > 
> > I've submitted patches with both options #1 and #2 above.
> > 
> > Thanks,
> > 
> > Sebastian
> 
> Ping.
> 
> Sorry for the lapse in attention to this.
> 
> Could you please clarify what is needed for this to be acceptable?
> I'm a little confused about what is being asked of me.

The problem is that kernel/power/hibernate.c:resume_store() is handed a
newline-terminated string, yes?  And if it blindly hands that string
over to name_to_dev_t(), name_to_dev_t() fails because the string is
wrong.

This is an oddity of the sysfs->kernel interface and altering
name_to_dev_t doesn't really seem appropriate for this problem - it
would be better to fix the caller to pass in the correct string.

Something like...

/*
 * Clean up a string which may have leading and/or trailing whitespace (as
 * defined by isspace()) by trimming off that whitespace.  Returns an address
 * which the caller must kfree(), or NULL on error.
 */
char *strim_copy(const char *s, gfp_t gfp)
{
	char *ret = kstrdup(skip_spaces(s), gfp);

	if (ret)
		strim(ret);
	return ret;
}
EXPORT_SYMBOL(strim_copy);
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