On Mon, 26 Oct 2009, David Howells wrote: > > From: Roel Kluin <roel.kluin@xxxxxxxxx> > > The variables are unsigned so the test `>= 0' is always true, > the `< 0' test always fails. The other part of > the test catches wrapped values. This is an excellent example of why I think that some gcc warnings are pure and utter sh*t, and why just blindly trying to avoid them then leads to worse code. > - if (datalen < 0 || datalen > PAGE_SIZE - 1) > + if (datalen > PAGE_SIZE - 1) > - if (fstop < 0 || fstop >= cache->fcull_percent) > + if (fstop >= cache->fcull_percent) > - if (bstop < 0 || bstop >= cache->bcull_percent) > + if (bstop >= cache->bcull_percent) You've now actively made the code more fragile, only to avoid a warning. The old code was clearly correct. The new code subtle depends on the type of comparison. I _hate_ those idiotic warnings, and in this case the "warning-free" code is actively worse than the original. A smart compiler would see that it's a range check, and one that could have been done as an unsigned comparison (well, for the constant compare case) regardless of the type of the variable being tested. So a _smart_ compiler wouldn't complain, but it might use the signedness information to silently simplify the comparison. A _stupid_ compiler complains, and thus forces people to either ignore the warning, or make the code worse. Which one would you prefer? Linus -- Linux-cachefs mailing list Linux-cachefs@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cachefs
