Re: [PATCH 2/5] seqlock: change __seqprop() to return the function pointer

kernel test robot
2023-09-13T19:24:07Z

Hi Oleg,

kernel test robot noticed the following build errors:

[auto build test ERROR on tip/locking/core]
[also build test ERROR on tip/sched/core linus/master v6.6-rc1 next-20230913]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Oleg-Nesterov/seqlock-simplify-SEQCOUNT_LOCKNAME/20230913-235245
base: tip/locking/core
patch link: https://lore.kernel.org/r/20230913154956.GA26245%40redhat.com
patch subject: [PATCH 2/5] seqlock: change __seqprop() to return the function pointer
config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20230914/202309140355.Sglwk06B-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230914/202309140355.Sglwk06B-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309140355.Sglwk06B-lkp@intel.com/

All errors (new ones prefixed by >>):

In file included from include/linux/hrtimer.h:20,
from include/linux/sched.h:20,
from arch/powerpc/kernel/syscalls.c:18:
include/linux/u64_stats_sync.h: In function '__u64_stats_fetch_retry':
>> include/linux/u64_stats_sync.h:176:36: error: passing argument 1 of '__seqprop_ptr' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
176 | return read_seqcount_retry(&syncp->seq, start);
| ^~~~~~~~~~~
include/linux/seqlock.h:304:59: note: in definition of macro 'seqprop_ptr'
304 | #define seqprop_ptr(s) __seqprop(s, ptr)(s)
| ^
include/linux/u64_stats_sync.h:176:16: note: in expansion of macro 'read_seqcount_retry'
176 | return read_seqcount_retry(&syncp->seq, start);
| ^~~~~~~~~~~~~~~~~~~
include/linux/seqlock.h:250:53: note: expected 'seqcount_t *' {aka 'struct seqcount *'} but argument is of type 'const seqcount_t *' {aka 'const struct seqcount *'}
250 | static inline seqcount_t *__seqprop_ptr(seqcount_t *s)
| ~~~~~~~~~~~~^
cc1: all warnings being treated as errors

vim +176 include/linux/u64_stats_sync.h

68107df5f2cb5d Frederic Weisbecker 2016-09-26 172
68107df5f2cb5d Frederic Weisbecker 2016-09-26 173 static inline bool __u64_stats_fetch_retry(const struct u64_stats_sync *syncp,
16b8a4761cbe50 Eric Dumazet 2010-06-22 174 unsigned int start)
16b8a4761cbe50 Eric Dumazet 2010-06-22 175 {
16b8a4761cbe50 Eric Dumazet 2010-06-22 @176 return read_seqcount_retry(&syncp->seq, start);
44b0c2957adc62 Thomas Gleixner 2022-08-25 177 }
44b0c2957adc62 Thomas Gleixner 2022-08-25 178 #endif /* !64 bit */
44b0c2957adc62 Thomas Gleixner 2022-08-25 179

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