On Fri, Oct 26, 2012 at 08:51:06AM +0200, Stefani Seibold wrote: > Am Freitag, den 26.10.2012, 14:11 +0800 schrieb Yuanhan Liu: > > On Fri, Oct 26, 2012 at 07:38:31AM +0200, Stefani Seibold wrote: > > > Am Freitag, den 26.10.2012, 09:46 +0800 schrieb Yuanhan Liu: > > > > From: Yuanhan Liu <yuanhan....@linux.intel.com> > > > > > > > > Firstly, this kind of type check doesn't work. It does something similay > > > > like following: > > > > void * __dummy = NULL; > > > > __buf = __dummy; > > > > > > > > __dummy is defined as void *. Thus it will not trigger warnings as > > > > expected. > > > > > > > > Second, we don't need that kind of check. Since the prototype > > > > of __kfifo_out is: > > > > unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, > > > > unsigned int len) > > > > > > > > buf is defined as void *, so we don't need do the type check. Remove it. > > > > > > > > LINK: https://lkml.org/lkml/2012/10/25/386 > > > > LINK: https://lkml.org/lkml/2012/10/25/584 > > > > > > > > Cc: Andrew Morton <a...@linux-foundation.org> > > > > Cc: Wei Yang <weiy...@linux.vnet.ibm.com> > > > > Cc: Stefani Seibold <stef...@seibold.net> > > > > Cc: Fengguang Wu <fengguang...@intel.com> > > > > Cc: Stephen Rothwell <s...@canb.auug.org.au> > > > > Signed-off-by: Yuanhan Liu <yuanhan....@linux.intel.com> > > > > --- > > > > > > > Did you tried to compile the whole kernel including all the drivers with > > > your patch? > > > > Hi Stefani, > > > > I did a build test, it did't introduce any new compile errors and > > warnings. While, I haven't tried make allmodconfig then. Does this patch > > seems wrong to you? > > > > Thanks, > > Yuanhan Liu > > Hi Liu, > > no the patch seems not wrong to me. But as you see with the previous > patch it is not easy to predict the side effects. > > An allmodconfig together with C=2 is necessary to check if there is no > side effects which current users of the kfifo API.
Hi Stefani, Make with C=2 will produce tons of warnings, hard to tell it introduces new warnings or not. I build some drivers used kfifo and samples as you suggested with C=2, find no new warnings. I will build all drivers that used kfifo with C=2 later, and will post the result here. > That is exactly what > i did again and again as i developed the kfifo API. > > Also you have to build the kfifo samples, since this example code use > all features of the kfifo API. > > And again: The kfifo is designed to do the many things at compile time, > not at runtime. If you modify the code, you have to check the compiler > assembler output for no degradation, especially in kfifo_put, kfifo_get, > kfifo_in, kfifo_out, __kfifo_in and __kfifo_out. Prevent runtime checks > if you can do it at compile time. This is the basic reasons to do it in > macros. Is it enought to check kernel/kfifo.o only? I build that file with and without this patch. And then dump it by objdump -D kernel/fifo.o to /tmp/kfifo.dump.with and /tmp/kfifo.dump.without, respectively. And the two dump file are exactly same. Thanks, Yuanhan Liu -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/