kcsan: Turn barrier instrumentation into macros
Some architectures use barriers in 'extern inline' functions, from which
we should not refer to static inline functions.
For example, building Alpha with gcc and W=1 shows:
./include/asm-generic/barrier.h:70:30: warning: 'kcsan_rmb' is static but used in inline function 'pmd_offset' which is not static
70 | #define smp_rmb() do { kcsan_rmb(); __smp_rmb(); } while (0)
| ^~~~~~~~~
./arch/alpha/include/asm/pgtable.h:293:9: note: in expansion of macro 'smp_rmb'
293 | smp_rmb(); /* see above */
| ^~~~~~~
Which seems to warn about 6.7.4#3 of the C standard:
"An inline definition of a function with external linkage shall not
contain a definition of a modifiable object with static or thread
storage duration, and shall not contain a reference to an identifier
with internal linkage."
Fix it by turning barrier instrumentation into macros, which matches
definitions in <asm/barrier.h>.
Perhaps we can revert this change in future, when there are no more
'extern inline' users left.
Link: https://lkml.kernel.org/r/202112041334.X44uWZXf-lkp@intel.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>