Re: [PATCH 7/8] uprobes: perform lockless SRCU-protected uprobes_tree lookup

Oleg Nesterov
2024-08-10T14:00:30Z

On 08/08, Oleg Nesterov wrote:
>
> On 07/31, Andrii Nakryiko wrote:
> >
> > static DEFINE_RWLOCK(uprobes_treelock); /* serialize rbtree access */
> > +static seqcount_rwlock_t uprobes_seqcount = SEQCNT_RWLOCK_ZERO(uprobes_seqcount, &uprobes_treelock);
>
> Just noticed... Why seqcount_rwlock_t?
>
> find_uprobe_rcu() doesn't use read_seqbegin_or_lock(),
> seqcount_t should work just fine.

Please ignore... I forgot that seqcount_t is not CONFIG_PREEMPT_RT-friendly.

Hmm. __seqprop_preemptible() returns 0, this doesn't look right... Nevermend.

Oleg.