On Thu, Jun 04, 2020 at 01:29:44PM -0700, Nick Desaulniers wrote: > On Thu, Jun 4, 2020 at 1:20 PM Kees Cook <keesc...@chromium.org> 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 <keesc...@chromium.org> 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-gli...@google.com/ > > > > [2] > > > > https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1tgqcr5vqkczwj0qxk6cernou6eedsuda...@mail.gmail.com/ > > > > [3] > > > > https://lore.kernel.org/lkml/ca+55afwgbgqhbp1fkxvrkepzyr5j8n1vkt1vzdz9knmpuxh...@mail.gmail.com/ > > > > [4] > > > > https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yvju65tplgn_ybynv0ve...@mail.gmail.com/ > > > > > > > > Signed-off-by: Kees Cook <keesc...@chromium.org> > > > > > > Reviewed-by: Nick Desaulniers <ndesaulni...@google.com> > > > > 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>
Ah yes, I always have to look up "-S". Good reminder! > 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? Ah cool. I've updated it now. It was really to narrow to a "known set of tags", and Linus's tree's tags always start with "v". -- Kees Cook
