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Date: Mon, 15 Sep 2014 23:55:28 +0200 From: Frans Klaver <fransklaver@...il.com> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Cc: Darren Hart <dvhart@...radead.org>, Corentin Chary <corentin.chary@...il.com>, Rafael Wysocki <rafael.j.wysocki@...el.com>, acpi4asus-user@...ts.sourceforge.net, platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org, "H. Peter Anvin" <hpa@...ux.intel.com> Subject: Re: [PATCH 10/13] eeepc-laptop: compare proper return values in get_cpufv On Mon, Sep 15, 2014 at 02:51:25PM -0700, Greg Kroah-Hartman wrote: > On Mon, Sep 15, 2014 at 02:49:02PM -0700, Darren Hart wrote: > > On Sat, Sep 13, 2014 at 01:06:49AM +0200, Frans Klaver wrote: > > > In get_cpufv the return value of get_acpi is stored in the cpufv struct. > > > Right before this value is checked for errors, it is and'ed with 0xff. > > > This means c->cur can never be less than zero. Besides that, the actual > > > error value is ignored. > > > > > > c->num is also and'ed with 0xff, which means we can ignore values below > > > zero. > > > > > > Check the result of get_acpi() right away. While at it, propagate the > > > error if we got one. > > > > > > Signed-off-by: Frans Klaver <fransklaver@...il.com> > > > --- > > > drivers/platform/x86/eeepc-laptop.c | 5 ++++- > > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c > > > index 47488d3..828db56 100644 > > > --- a/drivers/platform/x86/eeepc-laptop.c > > > +++ b/drivers/platform/x86/eeepc-laptop.c > > > @@ -332,9 +332,12 @@ struct eeepc_cpufv { > > > static int get_cpufv(struct eeepc_laptop *eeepc, struct eeepc_cpufv *c) > > > { > > > c->cur = get_acpi(eeepc, CM_ASL_CPUFV); > > > + if (c->cur < 0) > > > + return c->cur; > > > + > > > c->num = (c->cur >> 8) & 0xff; > > > c->cur &= 0xff; > > > - if (c->cur < 0 || c->num <= 0 || c->num > 12) > > > + if (c->num == 0 || c->num > 12) > > > return -ENODEV; > > > return 0; > > > > This patch is fine as is. However, Greg has supported propogating the error code > > through to the sysfs interface (if I understand him correctly on an earlier post > > to this list). This would require an addition change to this patch would > > propogated the get_cpufv error code in show_available_cpuv(), show_cpuv(), and > > store_cpuv(). As it is, we return -ENODEV on any failure, where an ACPI call > > error should probably return -ENXIO as I understand it. > > I really have no idea at this point in time what to recommend. How > about just stick with what is happening today so that: > > > However, there was a rather famous change in error code handling in which pulse > > audio broke and Linus was very upset with one of his maintainers. > > That doesn't happen :) So if I interpret that correctly, we're dropping the last patch (ENODEV -> ENXIO) from the series? That's fine by me. As mentioned earlier, I already saw something else break because I returned ENXIO instead of ENODEV. Maybe it's a good idea to try and document the expected behavior somewhere, if even Greg isn't sure what to do. Thanks, Frans -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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