On Sat, 16 Feb 2013, Arnd Bergmann wrote:
> On Saturday 16 February 2013, Simon Horman wrote:
> > > +void mmc_of_parse(struct mmc_host *host)
> > > +{
> > > + struct device_node *np;
> > > + u32 bus_width;
> > > + bool explicit_inv_wp, gpio_inv_wp = false;
> > > + enum of_gpio_flags flags;
> > > + int len, ret, gpio;
> > > +
> > > + if (!host->parent || !host->parent->of_node)
> > > + return;
> > > +
> > > + np = host->parent->of_node;
> > > +
> > > + /* "bus-width" is translated to MMC_CAP_*_BIT_DATA flags */
> > > + if (of_property_read_u32_array(np, "bus-width", &bus_width, 1) < 0)
> > > + dev_dbg(host->parent,
> > > + "\"bus-width\" property is missing, assuming 1 bit.\n");
> > > +
> > > + switch (bus_width) {
> >
> > kbuild tells me that gcc thinks that bus_width is used without being
> > initialised here. Assuming that of_property_read_u32_array always
> > initialises bus_width if it returns zero then perhaps it would be worth
> > considering using uninitialized_var().
>
> I think this is a false positive that I encountered before and that should be gone
> with gcc-4.7 or higher when using -O2 instead of -Os. I have a patch to disable
> -Wmaybe-uninitialized when builing with -Os. If that gets rid of the warning,
> I'd prefer not annotating it here.
Unfortunately, this does seem to be a real bug, I lost the default
initialisation to one somewhere along the way... I'll send a trivial
update. Stupidly, my cross-toolchain doesn't report this error.
Thanks
Guennadi
> There was some discussion about removing uninitialized_var() recently after it
> was found to hide some real bugs.
>
> Arnd
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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