[PATCH 1/1] signal: use BUILD_BUG() instead of _NSIG_WORDS_is_unsupported_size()

From: Oleg Nesterov
Date: Sun Sep 21 2014 - 12:46:07 EST


Kill _NSIG_WORDS_is_unsupported_size(), use BUILD_BUG() instead.
This simplifies the code, avoids the nested-externs warnings, and
this way we do not defer the problem to linker.

Also, fix the indentation in _SIG_SET_BINOP() and _SIG_SET_OP().

Note: this patch assumes that the code like "if (0) BUILD_BUG();"
is valid. If not (say __compiletime_error() is not defined and thus
__compiletime_error_fallback() uses a negative array) we should fix
BUILD_BUG() and/or BUILD_BUG_ON_MSG(). This code should be fine by
definition, this is the documented purpose of BUILD_BUG().

Reported-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
include/linux/signal.h | 28 ++++++++++++----------------
1 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/include/linux/signal.h b/include/linux/signal.h
index 750196f..14acfd5 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -67,7 +67,6 @@ static inline int sigismember(sigset_t *set, int _sig)

static inline int sigisemptyset(sigset_t *set)
{
- extern void _NSIG_WORDS_is_unsupported_size(void);
switch (_NSIG_WORDS) {
case 4:
return (set->sig[3] | set->sig[2] |
@@ -77,7 +76,7 @@ static inline int sigisemptyset(sigset_t *set)
case 1:
return set->sig[0] == 0;
default:
- _NSIG_WORDS_is_unsupported_size();
+ BUILD_BUG();
return 0;
}
}
@@ -90,24 +89,23 @@ static inline int sigisemptyset(sigset_t *set)
#define _SIG_SET_BINOP(name, op) \
static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
{ \
- extern void _NSIG_WORDS_is_unsupported_size(void); \
unsigned long a0, a1, a2, a3, b0, b1, b2, b3; \
\
switch (_NSIG_WORDS) { \
- case 4: \
+ case 4: \
a3 = a->sig[3]; a2 = a->sig[2]; \
b3 = b->sig[3]; b2 = b->sig[2]; \
r->sig[3] = op(a3, b3); \
r->sig[2] = op(a2, b2); \
- case 2: \
+ case 2: \
a1 = a->sig[1]; b1 = b->sig[1]; \
r->sig[1] = op(a1, b1); \
- case 1: \
+ case 1: \
a0 = a->sig[0]; b0 = b->sig[0]; \
r->sig[0] = op(a0, b0); \
break; \
- default: \
- _NSIG_WORDS_is_unsupported_size(); \
+ default: \
+ BUILD_BUG(); \
} \
}

@@ -128,16 +126,14 @@ _SIG_SET_BINOP(sigandnsets, _sig_andn)
#define _SIG_SET_OP(name, op) \
static inline void name(sigset_t *set) \
{ \
- extern void _NSIG_WORDS_is_unsupported_size(void); \
- \
switch (_NSIG_WORDS) { \
- case 4: set->sig[3] = op(set->sig[3]); \
- set->sig[2] = op(set->sig[2]); \
- case 2: set->sig[1] = op(set->sig[1]); \
- case 1: set->sig[0] = op(set->sig[0]); \
+ case 4: set->sig[3] = op(set->sig[3]); \
+ set->sig[2] = op(set->sig[2]); \
+ case 2: set->sig[1] = op(set->sig[1]); \
+ case 1: set->sig[0] = op(set->sig[0]); \
break; \
- default: \
- _NSIG_WORDS_is_unsupported_size(); \
+ default: \
+ BUILD_BUG(); \
} \
}

--
1.5.5.1


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