On Tue, 2015-06-23 at 20:44 -0400, nick wrote: > > On 2015-06-23 08:40 PM, Joe Perches wrote: > > On Wed, 2015-06-24 at 00:24 +0000, Kuninori Morimoto wrote: > >> Hi Joe, Nick > >> > >>>>>> This adds a cast to the variables,slave_id_rx and slave_id_rx > >>>>>> to uintptr_t before casting to void* in order to avoid build > >>>>>> warning on 64bit platforms for the function, sh_mmcif_request_dma_one. > >>>> [] > >>>>>> diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c > >>>> [] > >>>>>> @@ -398,8 +398,8 @@ sh_mmcif_request_dma_one(struct sh_mmcif_host *host, > >>>>>> > >>>>>> if (pdata) > >>>>>> slave_data = direction == DMA_MEM_TO_DEV ? > >>>>>> - (void *)pdata->slave_id_tx : > >>>>>> - (void *)pdata->slave_id_rx; > >>>>>> + (void *)(uintptr_t)pdata->slave_id_tx : > >>>>>> + (void *)(uintptr_t)pdata->slave_id_rx; > >>>> > >>>> It's far more common (~10:1) in the kernel to cast using > >>>> (<type> *)(unsigned long)<foo> > >>>> than > >>>> (<type> *)(uintptr_t)<foo> > >>>> > >>> Joe, > >>> I agree it's more common in the kernel but one of the maintainers when I sent > >>> this patch a month ago requested I use uintpr_t instead of unsigned long for > >>> the casting. Otherwise I would have done the cast to fix the build warning > >>> with unsigned long instead. > >> > >> This mail > >> http://thread.gmane.org/gmane.linux.kernel.mmc/32304 > > > > uintptr_t was introduced to avoid ptrdiff_t misuse in > > commit 142956af5250 ("fix abuses of ptrdiff_t") by Al Viro. > > > > unsigned long is preponderant, long is used about 1/4 as > > often as unsigned long, uintptr_t is relatively uncommon. > > > > If someone wants to go and convert the 800 or so casts to > > long or unsigned long to uintptr_t so that's the style most > > frequently used, that'd be different. I'm not going to > > submit any patches for that. > > > > > I am not disagreeing it was just easier to listen to the maintainer rather > then get in a technical argument over which type is better for the cast. Ulf Hansson is the maintainer. Laurent has authored a couple patches to that file and he gave you his opinion about using uintptr_t. I'm giving an opinion too, just with a little statistics. I think it's better to use the style that the kernel generally uses. I'll stop replying now. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
