]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
word-at-a-time: use the same return type for has_zero regardless of endianness
authorndesaulniers@google.com <ndesaulniers@google.com>
Tue, 1 Aug 2023 22:22:17 +0000 (15:22 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 2 Aug 2023 17:23:36 +0000 (10:23 -0700)
commit79e8328e5acbe691bbde029a52c89d70dcbc22f3
tree3abfe569415681d9d7438af4b93656abce9aedcf
parent5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
word-at-a-time: use the same return type for has_zero regardless of endianness

Compiling big-endian targets with Clang produces the diagnostic:

  fs/namei.c:2173:13: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
} while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
          ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                               ||
  fs/namei.c:2173:13: note: cast one or both operands to int to silence this warning

It appears that when has_zero was introduced, two definitions were
produced with different signatures (in particular different return
types).

Looking at the usage in hash_name() in fs/namei.c, I suspect that
has_zero() is meant to be invoked twice per while loop iteration; using
logical-or would not update `bdata` when `a` did not have zeros.  So I
think it's preferred to always return an unsigned long rather than a
bool than update the while loop in hash_name() to use a logical-or
rather than bitwise-or.

[ Also changed powerpc version to do the same  - Linus ]

Link: https://github.com/ClangBuiltLinux/linux/issues/1832
Link: https://lore.kernel.org/lkml/20230801-bitwise-v1-1-799bec468dc4@google.com/
Fixes: 36126f8f2ed8 ("word-at-a-time: make the interfaces truly generic")
Debugged-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/powerpc/include/asm/word-at-a-time.h
include/asm-generic/word-at-a-time.h