From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 19/20] scsi_dh_alua: update 'access_state' field Date: Wed, 30 Dec 2015 14:34:05 +0100 Message-ID: <20151230133405.GA15705@lst.de> References: <1449560260-53407-1-git-send-email-hare@suse.de> <1449560260-53407-20-git-send-email-hare@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from verein.lst.de ([213.95.11.211]:49570 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754022AbbL3NeH (ORCPT ); Wed, 30 Dec 2015 08:34:07 -0500 Content-Disposition: inline In-Reply-To: <1449560260-53407-20-git-send-email-hare@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Hannes Reinecke Cc: "Martin K. Petersen" , James Bottomley , Christoph Hellwig , Ewan Milne , Bart van Assche , linux-scsi@vger.kernel.org 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. >=20 > Signed-off-by: Hannes Reinecke > --- > drivers/scsi/device_handler/scsi_dh_alua.c | 29 ++++++++++++++++++++= +++++++++ > 1 file changed, 29 insertions(+) >=20 > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scs= i/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 > #include > #include > +#include > #include > #include > #include > @@ -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 { > }; > =20 > 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_d= evice *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); > =20 > /* Re-check list again to catch concurrent updates */ > @@ -370,13 +374,26 @@ static int alua_check_vpd(struct scsi_device *s= dev, struct alua_dh_data *h, > old_pg =3D pg; > /* port_group has changed. Update to new port group */ > if (h->pg !=3D pg) { > + unsigned long flags; > + > old_pg =3D 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. 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. > list_for_each_entry(tmp_pg, &port_group_list, node) { > + struct alua_dh_data *h; > + > if (tmp_pg->group_id !=3D group_id) > continue; > if (tmp_pg->device_id_len !=3D pg->device_id_len) > @@ -639,6 +658,12 @@ static int alua_rtpg(struct scsi_device *sdev, s= truct alua_port_group *pg) > continue; > tmp_pg->state =3D desc[0] & 0x0f; > tmp_pg->pref =3D desc[0] >> 7; > + rcu_read_lock(); > + list_for_each_entry_rcu(h, &tmp_pg->dh_list, node) { > + if (h->sdev) > + h->sdev->access_state =3D desc[0]; > + } > + rcu_read_unlock(); =D0=86'd expect h->=D1=95dev to always be non-NULL. With a little twea= k (see below) that should indeed be the case. > @@ -1086,6 +1112,9 @@ static void alua_bus_detach(struct scsi_device = *sdev) > h->sdev =3D 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. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html