Re: [PATCH-v2 2/9] target/pr: Use atomic bitop for se_dev_entry->pr_reg reservation check

Nicholas A. Bellinger
2015-05-25T21:59:58Z

On Fri, 2015-05-22 at 12:12 +0200, Bart Van Assche wrote:
> On 05/22/15 08:11, Nicholas A. Bellinger wrote:
> > diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
> > index e2c0eaf..def5bc8 100644
> > --- a/include/target/target_core_base.h
> > +++ b/include/target/target_core_base.h
> > @@ -638,7 +638,6 @@ struct se_lun_acl {
> > };
> >
> > struct se_dev_entry {
> > - bool def_pr_registered;
> > /* See transport_lunflags_table */
> > u32 lun_flags;
> > u32 mapped_lun;
> > @@ -655,7 +654,8 @@ struct se_dev_entry {
> > struct se_node_acl *se_node_acl;
> > struct se_lun_acl __rcu *se_lun_acl;
> > spinlock_t ua_lock;
> > - struct se_lun *se_lun;
> > + struct se_lun __rcu *se_lun;
> > + unsigned long pr_reg;
> > struct list_head alua_port_list;
> > struct list_head ua_list;
> > struct hlist_node link;
>
> Hello Nic,
>
> This change causes the "se_lun = deve->se_lun" assignment in
> transport_lookup_cmd_lun() to assign an RCU pointer to a non-RCU
> pointer. Shouldn't such an assignment be protected via rcu_dereference() ?
>

FYI, these assignments are done in patch #1.

This __rcu notation should be included there instead.