Messages in this thread Patch in this message | | | From | Luc Van Oostenryck <> | Subject | [PATCH v2] fix __percpu annotation in asm-generic | Date | Wed, 4 Dec 2019 02:06:23 +0100 |
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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: Dennis Zhou <dennis@kernel.org> Cc: Christoph Lameter <cl@linux.com> 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> ---
Change since v1: * use the fact that typeof() ignore the address space of its argument.
include/asm-generic/percpu.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h index c2de013b2cf4..35e4a53b83e6 100644 --- a/include/asm-generic/percpu.h +++ b/include/asm-generic/percpu.h @@ -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; \ -- 2.24.0
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