[SLOF] [PATCH] Fix remaining compiler warnings in sloffs.c

Nikunj A Dadhania nikunj at linux.vnet.ibm.com
Mon Aug 8 20:32:22 AEST 2016

Segher Boessenkool <segher at kernel.crashing.org> writes:

> On Mon, Aug 08, 2016 at 02:45:35PM +0530, Nikunj A Dadhania wrote:
>> >>> In the end, we just might want to add -fno-strict-aliasing to the
>> >>> HOSTCFLAGS, just like we already did it in make.rules for the normal
>> >>> CFLAGS, and call it a day.
>> >> 
>> >> Or you could fix the problems.  SLOF used to work with -fstrict-aliasing,
>> >> and it was a nice performance win.
>> >
>> > That's a question for Nikunj who committed that change a couple of years
>> > ago ...
>> > (see http://git.qemu.org/?p=SLOF.git;a=commitdiff;h=7eca6a5e56f468)
>> I remember that we had a discussion on this and BenH had suggested that
>> we cannot re-audit all the code for correctness with strict-aliasing. So
>> disable it.
> That's what -Wstrict-aliasing is for (needs -fstrict-aliasing active as
> well, to work).
> Rewriting the code to make it better can be quite a bit of work, of
> course.  But you could e.g. only use -fno-strict-aliasing on those files
> where -Wstrict-aliasing warns.

fill_udp_checksum() was the offending routine. And don't remember
there was any warning, we found the hard way. Computed checksum was
incorrect in certain cases.


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