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Code Issues Releases Wiki Activity

percpu: fix __percpu annotation in asm-generic

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The generic implementation of raw_cpu_generic_add_return() is:

        #define raw_cpu_generic_add_return(pcp, val)            \
        ({                                                      \
                typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp));       \
                                                                \
                *__p += val;                                    \
                *__p;                                           \
        })

where the 'pcp' argument is a __percpu lvalue.
There, the variable '__p' is declared as a __percpu pointer
the type of the address of 'pcp') but:
1) the value assigned to it, the return value of raw_cpu_ptr(), is
   a plain (__kernel) pointer, not a __percpu one.
2) this variable is dereferenced just after while a __percpu
   pointer is implicitly __noderef.

So, fix the declaration of the 'pcp' variable to its correct type:
the plain (non-percpu) pointer corresponding to pcp's address,
using the fact that typeof() ignores the address space and the
'noderef' attribute of its agument.

Same for raw_cpu_generic_xchg(), raw_cpu_generic_cmpxchg() &
raw_cpu_generic_cmpxchg_double().

This removes 209 warnings on ARM, 525 on ARM64, 220 on x86 &
more than 2600 on ppc64 (all of them with the default config).

Cc: Tejun Heo <tj@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Reported-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
This commit is contained in:
Luc Van Oostenryck 2019-12-04 02:06:23 +01:00 committed by Dennis Zhou
parent aedc0650f9
commit becef184df
1 changed files with 5 additions and 5 deletions
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10
include/asm-generic/percpu.h
View file

@ -74,7 +74,7 @@ do { \
#define raw_cpu_generic_add_return(pcp, val) \
({ \
typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp)); \
typeof(pcp) *__p = raw_cpu_ptr(&(pcp)); \
\
*__p += val; \
*__p; \
@ -82,7 +82,7 @@ do { \
#define raw_cpu_generic_xchg(pcp, nval) \
({ \
typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp)); \
typeof(pcp) *__p = raw_cpu_ptr(&(pcp)); \
typeof(pcp) __ret; \
__ret = *__p; \
*__p = nval; \
@ -91,7 +91,7 @@ do { \
#define raw_cpu_generic_cmpxchg(pcp, oval, nval) \
({ \
typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp)); \
typeof(pcp) *__p = raw_cpu_ptr(&(pcp)); \
typeof(pcp) __ret; \
__ret = *__p; \
if (__ret == (oval)) \
@ -101,8 +101,8 @@ do { \
#define raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
({ \
typeof(&(pcp1)) __p1 = raw_cpu_ptr(&(pcp1)); \
typeof(&(pcp2)) __p2 = raw_cpu_ptr(&(pcp2)); \
typeof(pcp1) *__p1 = raw_cpu_ptr(&(pcp1)); \
typeof(pcp2) *__p2 = raw_cpu_ptr(&(pcp2)); \
int __ret = 0; \
if (*__p1 == (oval1) && *__p2 == (oval2)) { \
*__p1 = nval1; \