From: Johannes Thumshirn Subject: Re: [PATCH] Update scsi host to use ida for host number Date: Tue, 01 Sep 2015 10:13:41 +0200 Message-ID: References: <1441052890-3600-1-git-send-email-leeman.duncan@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mx2.suse.de ([195.135.220.15]:37599 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753464AbbIAINm convert rfc822-to-8bit (ORCPT ); Tue, 1 Sep 2015 04:13:42 -0400 In-Reply-To: <1441052890-3600-1-git-send-email-leeman.duncan@gmail.com> (leeman duncan's message of "Mon, 31 Aug 2015 13:28:10 -0700") Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: leeman.duncan@gmail.com Cc: linux-scsi@vger.kernel.org, hare@suse.com, JBottomley@Parallels.com, Lee Duncan leeman.duncan@gmail.com writes: > From: Lee Duncan > > Each Scsi_host instance gets a host number starting > at 0, but this is implemented with an atomic integer, > and rollover doesn't seem to have been considered. > Another side-effect of this design is that scsi host > numbers used by iscsi are never reused, thereby making > rollover more likely. This patch converts Scsi_host > instances to use ida to manage their instance > numbers. > > This also means that host instance numbers will be > reused, when available. > > Signed-off-by: Lee Duncan > --- > drivers/scsi/hosts.c | 43 +++++++++++++++++++++++++++++++++++-------= - > 1 file changed, 35 insertions(+), 8 deletions(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 8bb173e01084..dade75478541 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -33,7 +33,7 @@ > #include > #include > #include > - > +#include > #include > #include > #include > @@ -42,7 +42,8 @@ > #include "scsi_logging.h" > =20 > =20 > -static atomic_t scsi_host_next_hn =3D ATOMIC_INIT(0); /* host_no for= next new host */ > +static DEFINE_SPINLOCK(host_index_lock); > +static DEFINE_IDA(host_index_ida); > =20 > =20 > static void scsi_host_cls_release(struct device *dev) > @@ -337,6 +338,10 @@ static void scsi_host_dev_release(struct device = *dev) > =20 > kfree(shost->shost_data); > =20 > + spin_lock(&host_index_lock); > + ida_remove(&host_index_ida, shost->host_no); > + spin_unlock(&host_index_lock); > + > if (parent) > put_device(parent); > kfree(shost); > @@ -353,6 +358,22 @@ static struct device_type scsi_host_type =3D { > .release =3D scsi_host_dev_release, > }; > =20 > +static int host_get_index(int *index) > +{ > + int error =3D -ENOMEM; > + > + do { > + if (!ida_pre_get(&host_index_ida, GFP_KERNEL)) > + break; > + spin_lock(&host_index_lock); > + error =3D ida_get_new(&host_index_ida, index); > + spin_unlock(&host_index_lock); > + } while (error =3D=3D -EAGAIN); > + > + return error; > +} > + > + > /** > * scsi_host_alloc - register a scsi host adapter instance. > * @sht: pointer to scsi host template > @@ -370,6 +391,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_hos= t_template *sht, int privsize) > { > struct Scsi_Host *shost; > gfp_t gfp_mask =3D GFP_KERNEL; > + int index; > + int error; > =20 > if (sht->unchecked_isa_dma && privsize) > gfp_mask |=3D __GFP_DMA; > @@ -388,11 +411,11 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_h= ost_template *sht, int privsize) > init_waitqueue_head(&shost->host_wait); > mutex_init(&shost->scan_mutex); > =20 > - /* > - * subtract one because we increment first then return, but we need= to > - * know what the next host number was before increment > - */ > - shost->host_no =3D atomic_inc_return(&scsi_host_next_hn) - 1; > + error =3D host_get_index(&index); > + if (error < 0) > + goto fail_kfree; > + shost->host_no =3D index; > + > shost->dma_channel =3D 0xff; > =20 > /* These three are default values which can be overridden */ > @@ -477,7 +500,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_hos= t_template *sht, int privsize) > shost_printk(KERN_WARNING, shost, > "error handler thread failed to spawn, error =3D %ld\n", > PTR_ERR(shost->ehandler)); > - goto fail_kfree; > + goto fail_free_index; > } > =20 > shost->tmf_work_q =3D alloc_workqueue("scsi_tmf_%d", > @@ -493,6 +516,10 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_ho= st_template *sht, int privsize) > =20 > fail_kthread: > kthread_stop(shost->ehandler); > + fail_free_index: > + spin_lock(&host_index_lock); > + ida_remove(&host_index_ida, index); > + spin_unlock(&host_index_lock); > fail_kfree: > kfree(shost); > return NULL; Reviewed-by: Johannes Thumshirn --=20 Johannes Thumshirn Storage jthumshirn@suse.de +49 911 74053 689 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg GF: Felix Imend=C3=B6rffer, Jane Smithard, Graham Norton HRB 21284 (AG N=C3=BCrnberg) Key fingerprint =3D EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850 -- 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