This looks good in general, but a couple nitpicks below:
> +static uint optimize_stpg;
> +module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
> +MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather
> than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is
> 0.");
why is this moved around in this patch? It doesn't seem related to the
rest of it, and isn't documented in the changelog either.
> {
> - struct alua_port_group *pg = NULL;
> + struct alua_port_group *pg;
looks like this should be folded into the patch that introduces the
unessecary NULL assignment.
> list_for_each_entry(pg, &port_group_list, node) {
> if (pg->group_id != group_id)
> @@ -214,18 +240,26 @@ struct alua_port_group *alua_get_pg(struct scsi_device
> *sdev,
> pg->group_id = group_id;
> pg->tpgs = tpgs;
> pg->state = TPGS_STATE_OPTIMIZED;
> + if (optimize_stpg)
> + pg->flags |= ALUA_OPTIMIZE_STPG;
why is this moved earlier here? Doing it from the beginning seems
useful to me, but I'd expect it in a separate patch with a proper
description.
> kref_init(&pg->kref);
> + INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
> + INIT_LIST_HEAD(&pg->rtpg_list);
> + INIT_LIST_HEAD(&pg->node);
> + spin_lock_init(&pg->lock);
>
> /* Re-check list again to catch concurrent updates */
> spin_lock(&port_group_lock);
> tmp_pg = alua_lookup_pg(id_str, id_size, group_id);
> if (tmp_pg) {
> spin_unlock(&port_group_lock);
> - kfree(pg);
> - return tmp_pg;
> + kref_put(&pg->kref, release_port_group);
> + pg = tmp_pg;
> + tmp_pg = NULL;
The only thing release_port_group does in addition to the kfree
is a list_del on pg->entry. But given that we never added
the pg to a list it doesn't need to be deleted, and it can't
have another reference. Why this change?
While we're at it, there are 6 calls to
'kref_put(&pg->kref, release_port_group)' in addition to this one,
so it might make sense to add a helper for it to the patch introducing
struct alua_port_group.
> * Extract the relative target port and the target port group
> * descriptor from the list of identificators.
> *
> - * Returns 0 or SCSI_DH_ error code on failure.
> + * Returns the target port group id or -1 on failure
That's not how I interpret the code below, it seems to always return
SCSI_DH_* values.
> + struct alua_port_group *pg = NULL, *old_pg = NULL;
> + bool pg_found = false;
> + pg = alua_get_pg(sdev, group_id, tpgs, id_str, id_size);
> + if (!pg)
> return SCSI_DH_NOMEM;
> + /* Check for existing port_group references */
> + spin_lock(&h->pg_lock);
> + if (h->pg) {
> + old_pg = pg;
> + /* port_group has changed. Update to new port group */
> + if (h->pg != pg) {
> + old_pg = h->pg;
> + rcu_assign_pointer(h->pg, pg);
> + h->pg->expiry = 0;
why do we set expiry to 0 here, but not if we didn't have a pg
yet? This could use a comment not just here but in all the places
that set it to zero.
> + pg_found = true;
pg_found should be pg_updated, right?
> + if (pg_found)
> + synchronize_rcu();
> + if (old_pg) {
> + if (old_pg->rtpg_sdev)
> + flush_delayed_work(&old_pg->rtpg_work);
> + kref_put(&old_pg->kref, release_port_group);
> + }
This code looks odd. I can't see why we need a synchronize_rcu here.
The only thing we should need is a kfree_rcu for the final free in
release_port_group. I also don't quite understand the flush_delayed_work.
As far as I can tell we only need it if rtpg_sdev is the sdev passed
in, so it we probably should check for that.
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