Re: [PATCH v3] eeepc-laptop: simplify parse_arg()
From: Darren Hart
Date: Wed Sep 17 2014 - 16:14:48 EST
On Wed, Sep 17, 2014 at 09:02:51PM +0200, Paul Bolle wrote:
> parse_arg() has three possible return values:
> -EINVAL if sscanf(), in short, fails;
> zero if "count" is zero; and
> "count" in all other cases
> But "count" will never be zero. See, parse_arg() is called by the
> various store functions. And the callchain of these functions starts
> with sysfs_kf_write(). And that function checks for a zero "count". So
> we can stop checking for a zero "count", drop the "count" argument
> entirely, and transform parse_arg() into a function that returns zero on
> success or a negative error. That, in turn, allows to make those store
> functions just return "count" on success. The net effect is that the
> code becomes a bit easier to understand.
> A nice side effect is that this GCC warning is silenced too:
> drivers/platform/x86/eeepc-laptop.c: In function âstore_sys_acpiâ:
> drivers/platform/x86/eeepc-laptop.c:279:10: warning: âvalueâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> int rv, value;
> Which is, of course, the reason to have a look at parse_arg().
> Signed-off-by: Paul Bolle <pebolle@xxxxxxxxxx>
> Still build tested only, but now on top of v3.17-rc5. Has Frans tested
> writing zero length values to these sysfs files?
> v3: store_sys_acpi() again returns -EIO if set_acpi() fails.
> v2: let store_sys_acpi() return whatever error set_acpi() returns
> instead of remapping it to EIO. The new line about that in the commit
> explanation is silly, but I couldn't come up with a better explanation.
Intel Open Source Technology Center
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