On 12/30/2015 02:34 PM, Christoph Hellwig wrote:
On Tue, Dec 08, 2015 at 08:37:39AM +0100, Hannes Reinecke wrote:Track attached SCSI devices and update the 'access_state' field whenever an ALUA state change has been detected. Signed-off-by: Hannes Reinecke <hare@xxxxxxx> --- drivers/scsi/device_handler/scsi_dh_alua.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index 6c6ff0b..d01c86407 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -24,6 +24,7 @@ #include <linux/module.h> #include <asm/unaligned.h> #include <scsi/scsi.h> +#include <scsi/scsi_proto.h> #include <scsi/scsi_dbg.h> #include <scsi/scsi_eh.h> #include <scsi/scsi_dh.h> @@ -76,6 +77,7 @@ static struct workqueue_struct *kaluad_wq; struct alua_port_group { struct kref kref; struct list_head node; + struct list_head dh_list; unsigned char device_id_str[256]; int device_id_len; int group_id; @@ -93,6 +95,7 @@ struct alua_port_group { }; struct alua_dh_data { + struct list_head node; struct alua_port_group *pg; int rel_port; spinlock_t pg_lock; @@ -243,6 +246,7 @@ struct alua_port_group *alua_get_pg(struct scsi_device *sdev, INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work); INIT_LIST_HEAD(&pg->rtpg_list); INIT_LIST_HEAD(&pg->node); + INIT_LIST_HEAD(&pg->dh_list); spin_lock_init(&pg->lock); /* Re-check list again to catch concurrent updates */ @@ -370,13 +374,26 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, old_pg = pg; /* port_group has changed. Update to new port group */ if (h->pg != pg) { + unsigned long flags; + old_pg = h->pg; rcu_assign_pointer(h->pg, pg); + spin_lock_irqsave(&old_pg->lock, flags); + list_del_rcu(&h->node); + spin_unlock_irqrestore(&old_pg->lock, flags); + spin_lock_irqsave(&pg->lock, flags); + list_add_rcu(&h->node, &pg->dh_list); + spin_unlock_irqrestore(&pg->lock, flags);I think it makes more sense to remove it from the old list before assining the new h->pg pointer to stay consistant.
Hmm. Yes, good point.
Also the add code is not common with the other half of the outer branch, it would be nice to find a way to share the code between those two branches.
Indeed, it would. But so far I haven't found a nice way for that...
list_for_each_entry(tmp_pg, &port_group_list, node) { + struct alua_dh_data *h; + if (tmp_pg->group_id != group_id) continue; if (tmp_pg->device_id_len != pg->device_id_len) @@ -639,6 +658,12 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) continue; tmp_pg->state = desc[0] & 0x0f; tmp_pg->pref = desc[0] >> 7; + rcu_read_lock(); + list_for_each_entry_rcu(h, &tmp_pg->dh_list, node) { + if (h->sdev) + h->sdev->access_state = desc[0]; + } + rcu_read_unlock();І'd expect h->ѕdev to always be non-NULL. With a little tweak (see below) that should indeed be the case.@@ -1086,6 +1112,9 @@ static void alua_bus_detach(struct scsi_device *sdev) h->sdev = NULL; spin_unlock(&h->pg_lock); if (pg) { + spin_lock(&pg->lock); + list_del_rcu(&h->node); + spin_unlock(&pg->lock); synchronize_rcu(); if (pg->rtpg_sdev) flush_delayed_work(&pg->rtpg_work);Here we'd just need to make sure to do the list_del before setting h->sdev to NULL.
Okay, true. Will do. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
