On Thu, Jun 4, 2020 at 1:20 PM Kees Cook [off-list ref] wrote:

On Thu, Jun 04, 2020 at 12:29:17PM -0700, Nick Desaulniers wrote:

quoted

On Wed, Jun 3, 2020 at 4:32 PM Kees Cook [off-list ref] wrote:

quoted

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@google.com/ (local)
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ (local)
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ (local)
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ (local)

Signed-off-by: Kees Cook <redacted>

Reviewed-by: Nick Desaulniers <redacted>

Thanks for the reviews!

quoted

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