On Mon, Sep 16, 2013 at 10:40:00AM +0200, Oliver Neukum wrote: > On Mon, 2013-09-16 at 13:38 +0930, Rusty Russell wrote: > > Predates git, does anyone remember the rationale? > > > > ie: > > int test_bit(int nr, const volatile unsigned long *addr) > > > > I noticed because gcc failed to elimiate some code in a patch I was > > playing with. > > > > I'm nervous about subtle bugs involved in ripping it out, even if noone > > knows why. Should I add __test_bit()? > > It seems to me that if you do > > b = *ptr & 0xf; > c = b << 2; > if (test_bit(1, ptr)) > > the compiler could optimize away the memory access on ptr without > the volatile. We'd have to add a lot of mb(). > > Regards > Oliver
What is this code supposed to do? Any specific examples? -- MST -- 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/
