From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ewan Milne Subject: Re: [PATCH 22/23] scsi_dh_alua: update 'access_state' field Date: Thu, 11 Feb 2016 15:37:05 -0500 Message-ID: <1455223025.22112.340.camel@localhost.localdomain> References: <1454942086-128704-1-git-send-email-hare@suse.de> <1454942086-128704-23-git-send-email-hare@suse.de> Reply-To: emilne@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:57068 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbcBKUhG (ORCPT ); Thu, 11 Feb 2016 15:37:06 -0500 In-Reply-To: <1454942086-128704-23-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" , Christoph Hellwig , Bart van Assche , James Bottomley , linux-scsi@vger.kernel.org On Mon, 2016-02-08 at 15:34 +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 | 45 ++++++++++++++++++++++++++++-- > 1 file changed, 43 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c > index 51126b78..7bcc075 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 > @@ -75,6 +76,7 @@ struct alua_port_group { > struct kref kref; > struct rcu_head rcu; > struct list_head node; > + struct list_head dh_list; > unsigned char device_id_str[256]; > int device_id_len; > int group_id; > @@ -92,6 +94,7 @@ struct alua_port_group { > }; > > struct alua_dh_data { > + struct list_head node; > struct alua_port_group *pg; > int group_id; > spinlock_t pg_lock; > @@ -247,6 +250,7 @@ struct alua_port_group *alua_alloc_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); > > spin_lock(&port_group_lock); > @@ -328,6 +332,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, > { > int rel_port = -1, group_id; > struct alua_port_group *pg, *old_pg = NULL; > + bool pg_updated; > + unsigned long flags; > > group_id = scsi_vpd_tpg_id(sdev, &rel_port); > if (group_id < 0) { > @@ -357,13 +363,25 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, > old_pg = h->pg; > if (old_pg != pg) { > /* port group has changed. Update to new port group */ > + if (h->pg) { > + spin_lock_irqsave(&old_pg->lock, flags); > + list_del_rcu(&h->node); > + spin_unlock_irqrestore(&old_pg->lock, flags); > + } > rcu_assign_pointer(h->pg, pg); > + pg_updated = true; > } > if (sdev->synchronous_alua) > pg->flags |= ALUA_SYNC_STPG; > alua_rtpg_queue(h->pg, sdev, NULL, true); > spin_unlock(&h->pg_lock); > > + if (pg_updated) { > + spin_lock_irqsave(&pg->lock, flags); > + list_add_rcu(&h->node, &pg->dh_list); > + spin_unlock_irqrestore(&pg->lock, flags); > + } > + > if (old_pg) > kref_put(&old_pg->kref, release_port_group); > > @@ -613,8 +631,18 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) > if (spin_trylock_irqsave(&tmp_pg->lock, flags)) { > if ((tmp_pg == pg) || > !(tmp_pg->flags & ALUA_PG_RUNNING)) { > + struct alua_dh_data *h; > + > 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) { > + /* h->sdev should always be valid */ > + BUG_ON(!h->sdev); > + h->sdev->access_state = desc[0]; Here you did not mask desc[0] with 0x0f like you did in other places in the code. > + } > + rcu_read_unlock(); > } > if (tmp_pg == pg) > valid_states = desc[1]; > @@ -646,10 +674,19 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) > pg->interval = 2; > err = SCSI_DH_RETRY; > } else { > + struct alua_dh_data *h; > + > /* Transitioning time exceeded, set port to standby */ > err = SCSI_DH_IO; > pg->state = SCSI_ACCESS_STATE_STANDBY; > pg->expiry = 0; > + rcu_read_lock(); > + list_for_each_entry_rcu(h, &pg->dh_list, node) { > + BUG_ON(!h->sdev); > + h->sdev->access_state = (pg->state & 0x0f) | > + (pg->pref << 7); Since SCSI_ACCESS_STATE_PREFERRED is #defined as 0x80 in scsi_proto.h you should use | (pg->pref ? SCSI_ACCESS_STATE_PREFERRED : 0) here rather than just shifting, otherwise you will have a hard to find bug if somebody changes the constant. (But I would prefer keeping them separate anyway.) > + } > + rcu_read_unlock(); > } > break; > case SCSI_ACCESS_STATE_OFFLINE: > @@ -1053,6 +1090,7 @@ static int alua_bus_attach(struct scsi_device *sdev) > rcu_assign_pointer(h->pg, NULL); > h->init_error = SCSI_DH_OK; > h->sdev = sdev; > + INIT_LIST_HEAD(&h->node); > > mutex_init(&h->init_mutex); > err = alua_initialize(sdev, h); > @@ -1082,9 +1120,12 @@ static void alua_bus_detach(struct scsi_device *sdev) > rcu_assign_pointer(h->pg, NULL); > h->sdev = NULL; > spin_unlock(&h->pg_lock); > - if (pg) > + if (pg) { > + spin_lock(&pg->lock); > + list_del_rcu(&h->node); > + spin_unlock(&pg->lock); > kref_put(&pg->kref, release_port_group); > - > + } > sdev->handler_data = NULL; > kfree(h); > } Reviewed-by: Ewan D. Milne