On Thu, Jun 4, 2020 at 1:20 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > On Thu, Jun 04, 2020 at 12:29:17PM -0700, Nick Desaulniers wrote: > > On Wed, Jun 3, 2020 at 4:32 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > > > Using uninitialized_var() is dangerous as it papers over real bugs[1] > > > (or can in the future), and suppresses unrelated compiler warnings (e.g. > > > "unused variable"). If the compiler thinks it is uninitialized, either > > > simply initialize the variable or make compiler changes. As a precursor > > > to removing[2] this[3] macro[4], just remove this variable since it was > > > actually unused: > > > > > > drivers/ide/ide-taskfile.c:232:34: warning: unused variable 'flags' [-Wunused-variable] > > > unsigned long uninitialized_var(flags); > > > ^ > > > > > > [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@xxxxxxxxxx/ > > > [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@xxxxxxxxxxxxxx/ > > > [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@xxxxxxxxxxxxxx/ > > > [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@xxxxxxxxxxxxxx/ > > > > > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > > > Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > Thanks for the reviews! > > > Fixes ce1e518190ea ("ide: don't disable interrupts during kmap_atomic()") > > I originally avoided adding Fixes tags because I didn't want these > changes backported into a -stable without -Wmaybe-uninitialized > disabled, but in these cases (variable removal), that actually does make > sense. Thanks! Saravana showed me a cool trick for quickly finding commits that removed a particular identifier that I find faster than `git blame` or vim-fugitive for the purpose of Fixes tags: $ git log -S <string> <file> I've added it to our wiki: https://github.com/ClangBuiltLinux/linux/wiki/Command-line-tips-and-tricks#for-finding-which-commit-may-have-removed-a-string-try. I should update the first tip; what was your suggestion for constraining the search to the current remote? -- Thanks, ~Nick Desaulniers
