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| author | Vincent Mailhol <mailhol.vincent@wanadoo.fr> | 2022-03-24 03:37:42 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-04-05 10:24:40 +0200 |
| commit | 9ce02f0fc68326dd1f87a0a3a4c6ae7fdd39e6f6 (patch) | |
| tree | 24bf14bc941531e11bdde86381010781606a3005 | |
| parent | x86/mm/tlb: Revert retpoline avoidance approach (diff) | |
| download | linux-9ce02f0fc68326dd1f87a0a3a4c6ae7fdd39e6f6.tar.xz linux-9ce02f0fc68326dd1f87a0a3a4c6ae7fdd39e6f6.zip | |
x86/bug: Prevent shadowing in __WARN_FLAGS
The macro __WARN_FLAGS() uses a local variable named "f". This being a
common name, there is a risk of shadowing other variables.
For example, GCC would yield:
| In file included from ./include/linux/bug.h:5,
| from ./include/linux/cpumask.h:14,
| from ./arch/x86/include/asm/cpumask.h:5,
| from ./arch/x86/include/asm/msr.h:11,
| from ./arch/x86/include/asm/processor.h:22,
| from ./arch/x86/include/asm/timex.h:5,
| from ./include/linux/timex.h:65,
| from ./include/linux/time32.h:13,
| from ./include/linux/time.h:60,
| from ./include/linux/stat.h:19,
| from ./include/linux/module.h:13,
| from virt/lib/irqbypass.mod.c:1:
| ./include/linux/rcupdate.h: In function 'rcu_head_after_call_rcu':
| ./arch/x86/include/asm/bug.h:80:21: warning: declaration of 'f' shadows a parameter [-Wshadow]
| 80 | __auto_type f = BUGFLAG_WARNING|(flags); \
| | ^
| ./include/asm-generic/bug.h:106:17: note: in expansion of macro '__WARN_FLAGS'
| 106 | __WARN_FLAGS(BUGFLAG_ONCE | \
| | ^~~~~~~~~~~~
| ./include/linux/rcupdate.h:1007:9: note: in expansion of macro 'WARN_ON_ONCE'
| 1007 | WARN_ON_ONCE(func != (rcu_callback_t)~0L);
| | ^~~~~~~~~~~~
| In file included from ./include/linux/rbtree.h:24,
| from ./include/linux/mm_types.h:11,
| from ./include/linux/buildid.h:5,
| from ./include/linux/module.h:14,
| from virt/lib/irqbypass.mod.c:1:
| ./include/linux/rcupdate.h:1001:62: note: shadowed declaration is here
| 1001 | rcu_head_after_call_rcu(struct rcu_head *rhp, rcu_callback_t f)
| | ~~~~~~~~~~~~~~~^
For reference, sparse also warns about it, c.f. [1].
This patch renames the variable from f to __flags (with two underscore
prefixes as suggested in the Linux kernel coding style [2]) in order
to prevent collisions.
[1] https://lore.kernel.org/all/CAFGhKbyifH1a+nAMCvWM88TK6fpNPdzFtUXPmRGnnQeePV+1sw@mail.gmail.com/
[2] Linux kernel coding style, section 12) Macros, Enums and RTL,
paragraph 5) namespace collisions when defining local variables in
macros resembling functions
https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl
Fixes: bfb1a7c91fb7 ("x86/bug: Merge annotate_reachable() into_BUG_FLAGS() asm")
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20220324023742.106546-1-mailhol.vincent@wanadoo.fr
| -rw-r--r-- | arch/x86/include/asm/bug.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h index 4d20a293c6fd..aaf0cb0db4ae 100644 --- a/arch/x86/include/asm/bug.h +++ b/arch/x86/include/asm/bug.h @@ -78,9 +78,9 @@ do { \ */ #define __WARN_FLAGS(flags) \ do { \ - __auto_type f = BUGFLAG_WARNING|(flags); \ + __auto_type __flags = BUGFLAG_WARNING|(flags); \ instrumentation_begin(); \ - _BUG_FLAGS(ASM_UD2, f, ASM_REACHABLE); \ + _BUG_FLAGS(ASM_UD2, __flags, ASM_REACHABLE); \ instrumentation_end(); \ } while (0) |