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

kernel test robot
2023-09-13T17:38:02Z

Hi Oleg,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/locking/core]
[also build test WARNING 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: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230914/202309140117.J5VH7p4z-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230914/202309140117.J5VH7p4z-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/202309140117.J5VH7p4z-lkp@intel.com/

All warnings (new ones prefixed by >>):

In file included from include/linux/rbtree_latch.h:37,
from include/linux/bpf.h:14,
from include/linux/filter.h:9,
from kernel/bpf/core.c:21:
include/linux/u64_stats_sync.h: In function '__u64_stats_fetch_retry':
>> include/linux/u64_stats_sync.h:176:36: warning: passing argument 1 of '__seqprop_ptr' discards 'const' qualifier from pointer target type [-Wdiscarded-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)
| ~~~~~~~~~~~~^
kernel/bpf/core.c: At top level:
kernel/bpf/core.c:1638:12: warning: no previous prototype for 'bpf_probe_read_kernel' [-Wmissing-prototypes]
1638 | u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
| ^~~~~~~~~~~~~~~~~~~~~
--
In file included from include/linux/rbtree_latch.h:37,
from include/linux/bpf.h:14,
from kernel/bpf/syscall.c:4:
include/linux/u64_stats_sync.h: In function '__u64_stats_fetch_retry':
>> include/linux/u64_stats_sync.h:176:36: warning: passing argument 1 of '__seqprop_ptr' discards 'const' qualifier from pointer target type [-Wdiscarded-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)
| ~~~~~~~~~~~~^
--
In file included from include/linux/hrtimer.h:20,
from include/linux/sched.h:20,
from include/linux/ptrace.h:6,
from include/uapi/asm-generic/bpf_perf_event.h:4,
from ./arch/m68k/include/generated/uapi/asm/bpf_perf_event.h:1,
from include/uapi/linux/bpf_perf_event.h:11,
from kernel/bpf/btf.c:6:
include/linux/u64_stats_sync.h: In function '__u64_stats_fetch_retry':
>> include/linux/u64_stats_sync.h:176:36: warning: passing argument 1 of '__seqprop_ptr' discards 'const' qualifier from pointer target type [-Wdiscarded-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)
| ~~~~~~~~~~~~^
kernel/bpf/btf.c: In function 'btf_seq_show':
kernel/bpf/btf.c:7075:29: warning: function 'btf_seq_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
7075 | seq_vprintf((struct seq_file *)show->target, fmt, args);
| ^~~~~~~~
kernel/bpf/btf.c: In function 'btf_snprintf_show':
kernel/bpf/btf.c:7112:9: warning: function 'btf_snprintf_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
7112 | len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
| ^~~

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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