On Tue, May 24, 2022 at 8:59 AM Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote:
>
>
>
> On 2022-05-23 00:47, Song Liu wrote:
> >> A problem here is that `struct r5l_log` of `conf->log` is private to raid5-cache.c and gcc below version 10 (wrongly) regards the `typeof(*p) *local` declaration of __rcu_access_pointer as a dereference:
> >>
> >> CC drivers/md/raid5.o
> >>
> >> In file included from ./include/linux/rculist.h:11:0,
> >>
> >> from ./include/linux/dcache.h:8,
> >>
> >> from ./include/linux/fs.h:8,
> >>
> >> from ./include/linux/highmem.h:5,
> >>
> >> from ./include/linux/bvec.h:10,
> >>
> >> from ./include/linux/blk_types.h:10,
> >>
> >> from ./include/linux/blkdev.h:9,
> >>
> >> from drivers/md/raid5.c:38:
> >>
> >> drivers/md/raid5-log.h: In function ‘log_stripe’:
> >>
> >> ./include/linux/rcupdate.h:384:9: error: dereferencing pointer to incomplete type ‘struct r5l_log’
> >>
> >> typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
> >>
> >> ^
> >>
> >> ./include/linux/rcupdate.h:495:31: note: in expansion of macro ‘__rcu_access_pointer’
> >>
> >> #define rcu_access_pointer(p) __rcu_access_pointer((p), __UNIQUE_ID(rcu), __rcu)
> >>
> >> ^~~~~~~~~~~~~~~~~~~~
> >>
> >> drivers/md/raid5-log.h:61:6: note: in expansion of macro ‘rcu_access_pointer’
> >>
> >> if (rcu_access_pointer(conf->log)) {
> >>
> >> ^~~~~~~~~~~~~~~~~~
> >>
> >> make[2]: *** [scripts/Makefile.build:288: drivers/md/raid5.o] Error 1
> >>
> >> make[1]: *** [scripts/Makefile.build:550: drivers/md] Error 2
> >>
> >> make: *** [Makefile:1834: drivers] Error 2
> >
> > This is annoying.. And there are a few other cases in raid5-log.h and
> > raid5.c.
> >
> > Maybe we should move the definition of r5l_log to raid5-log.h?
>
> That's the only solution I can think of, and what I'll likely do for v2.
> If anyone has a better solution I'm open to it.
Let's move the definition.
Thanks,
Song
