Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 31 Jul 2015 12:20:57 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/4] percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire() |
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On Wed, Jul 22, 2015 at 11:15:35PM +0200, Oleg Nesterov wrote: > Add percpu_rwsem_release() and percpu_rwsem_acquire() for the users > which need to return to userspace with percpu-rwsem lock held and/or > pass the ownership to another thread. > > TODO: change percpu_rwsem_release() to use rwsem_clear_owner(). We can > either fold kernel/locking/rwsem.h into include/linux/rwsem.h, or add > the non-inline percpu_rwsem_clear_owner(). > > Signed-off-by: Oleg Nesterov <oleg@redhat.com> > --- > include/linux/percpu-rwsem.h | 19 +++++++++++++++++++ > 1 files changed, 19 insertions(+), 0 deletions(-) > > diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h > index 3ebf982..06af654 100644 > --- a/include/linux/percpu-rwsem.h > +++ b/include/linux/percpu-rwsem.h > @@ -33,4 +33,23 @@ extern void percpu_free_rwsem(struct percpu_rw_semaphore *); > __percpu_init_rwsem(brw, #brw, &rwsem_key); \ > }) > > + > +#define percpu_rwsem_is_held(sem) lockdep_is_held(&(sem)->rw_sem) > + > +static inline void percpu_rwsem_release(struct percpu_rw_semaphore *sem, > + bool read, unsigned long ip) > +{ > + lock_release(&sem->rw_sem.dep_map, 1, ip); > +#ifdef CONFIG_RWSEM_SPIN_ON_OWNER > + if (!read) > + sem->rw_sem.owner = NULL; > +#endif > +} > + > +static inline void percpu_rwsem_acquire(struct percpu_rw_semaphore *sem, > + bool read, unsigned long ip) > +{ > + lock_acquire(&sem->rw_sem.dep_map, 0, 1, read, 1, NULL, ip); > +}
This is of course entirely vile.. Can't we open code that in the freezer code? Having helpers here might give some people the impression that this is a sane thing to do.
Also, when you do that in the freezer, put a big honking comment on it.
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