From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 19/20] scsi_dh_alua: update 'access_state' field Date: Thu, 31 Dec 2015 15:15:05 +0100 Message-ID: <56853869.2020403@suse.de> References: <1449560260-53407-1-git-send-email-hare@suse.de> <1449560260-53407-20-git-send-email-hare@suse.de> <20151230133405.GA15705@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mx2.suse.de ([195.135.220.15]:34266 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751183AbbLaOPJ (ORCPT ); Thu, 31 Dec 2015 09:15:09 -0500 In-Reply-To: <20151230133405.GA15705@lst.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig Cc: "Martin K. Petersen" , James Bottomley , Ewan Milne , Bart van Assche , linux-scsi@vger.kernel.org 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 >> --- >> 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/sc= si/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 { >> }; >> >> 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 =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. > 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 !=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, = struct 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 tw= eak (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. > Okay, true. Will do. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg GF: J. Hawn, J. Guild, F. Imend=C3=B6rffer, HRB 16746 (AG N=C3=BCrnberg= ) -- 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