On Mon, Nov 23, 2020 at 05:32:51PM -0800, Nick Desaulniers wrote: > On Sun, Nov 22, 2020 at 8:17 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > On Fri, Nov 20, 2020 at 11:51:42AM -0800, Jakub Kicinski wrote: > > > If none of the 140 patches here fix a real bug, and there is no change > > > to machine code then it sounds to me like a W=2 kind of a warning. > > > > FWIW, this series has found at least one bug so far: > > https://lore.kernel.org/lkml/CAFCwf11izHF=g1mGry1fE5kvFFFrxzhPSM6qKAO8gxSp=Kr_CQ@xxxxxxxxxxxxxx/ > > So looks like the bulk of these are: > switch (x) { > case 0: > ++x; > default: > break; > } This should not generate a warning. > > I have a patch that fixes those up for clang: > https://reviews.llvm.org/D91895 > > There's 3 other cases that don't quite match between GCC and Clang I > observe in the kernel: > switch (x) { > case 0: > ++x; > default: > goto y; > } > y:; This should generate a warning. > > switch (x) { > case 0: > ++x; > default: > return; > } Warn for this. > > switch (x) { > case 0: > ++x; > default: > ; > } Don't warn for this. If adding a break statement changes the flow of the code then warn about potentially missing break statements, but if it doesn't change anything then don't warn about it. regards, dan carpenter
