On Sat, Aug 17, 2013 at 06:37:56PM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > > According to the C standard 3.4.3p3, overflow of a signed integer results > in undefined behavior. This commit therefore changes the definitions > of time_after(), time_after_eq(), time_after64(), and time_after_eq64() > to avoid this undefined behavior. The trick is that the subtraction > is done using unsigned arithmetic, which according to 6.2.5p9 cannot > overflow because it is defined as modulo arithmetic. This has the added > (though admittedly quite small) benefit of shortening two lines of code > by four characters each. > > Note that the C standard considers the cast from unsigned to > signed to be implementation-defined, see 6.3.1.3p3. However, on a > two-complement system, an implementation that defines anything other > than a reinterpretation of the bits is free come to me, and I will be
s/free come/free to come/ > happy to act as a witness for its being committed to an insane asylum. With the typo above fixed: Reviewed-by: Josh Triplett <j...@joshtriplett.org> -- 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/
