Re: [PATCH 2/3] rwsem: Implement down_read_interruptible

[Waiman Long]

On 12/7/20 4:02 AM, Peter Zijlstra wrote:
> On Thu, Dec 03, 2020 at 08:59:13PM -0500, Waiman Long wrote:
> > On 12/3/20 3:11 PM, Eric W. Biederman wrote:
> > > +static inline int __down_read_interruptible(struct rw_semaphore *sem)
> > > +{
> > > +	if (!rwsem_read_trylock(sem)) {
> > > +		if (IS_ERR(rwsem_down_read_slowpath(sem, TASK_INTERRUPTIBLE)))
> > > +			return -EINTR;
> > > +		DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem), sem);
> > > +	} else {
> > > +		rwsem_set_reader_owned(sem);
> > > +	}
> > > +	return 0;
> > > +}
> > > +
> > >    static inline int __down_read_killable(struct rw_semaphore *sem)
> > >    {
> > >    	if (!rwsem_read_trylock(sem)) {
> > > @@ -1495,6 +1507,20 @@ void __sched down_read(struct rw_semaphore *sem)
> > >    }
> > >    EXPORT_SYMBOL(down_read);
> > > +int __sched down_read_interruptible(struct rw_semaphore *sem)
> > > +{
> > > +	might_sleep();
> > > +	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);
> > > +
> > > +	if (LOCK_CONTENDED_RETURN(sem, __down_read_trylock, __down_read_interruptible)) {
> > > +		rwsem_release(&sem->dep_map, _RET_IP_);
> > > +		return -EINTR;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +EXPORT_SYMBOL(down_read_interruptible);
> > > +
> > >    int __sched down_read_killable(struct rw_semaphore *sem)
> > >    {
> > >    	might_sleep();
> > Acked-by: Waiman Long <longman@xxxxxxxxxx>
> Yeah, that seems correct.. There's an unfortunate amount of copy-paste
> there though.
>
> Do we want to follow that up with something like this?

I am actually thinking about similar streamlining once the patch lands.

Your suggested changes look fine to me.

Cheers,
Longman