Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933443Ab2BBTqh (ORCPT ); Thu, 2 Feb 2012 14:46:37 -0500 Received: from e8.ny.us.ibm.com ([32.97.182.138]:45721 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757159Ab2BBTqf (ORCPT ); Thu, 2 Feb 2012 14:46:35 -0500 Subject: Re: [PATCH] scsi_dh_rdac: Fix for unbalanced reference count From: Chandra Seetharaman Reply-To: sekharan@us.ibm.com To: "Moger, Babu" Cc: "linux-kernel@vger.kernel.org" , device-mapper development , Mike Snitzer In-Reply-To: <77471C95FAFD844C8CA02DD4F4C5FE2B01032D@SACEXCMBX02-PRD.hq.netapp.com> References: <77471C95FAFD844C8CA02DD4F4C5FE2B01032D@SACEXCMBX02-PRD.hq.netapp.com> Content-Type: text/plain; charset="UTF-8" Organization: IBM Date: Thu, 02 Feb 2012 13:43:55 -0600 Message-ID: <1328211835.2213.27.camel@chandra-lucid.austin.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12020219-9360-0000-0000-0000030B35A5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6316 Lines: 164 Reviewed-by: Chandra Seetharaman On Thu, 2012-02-02 at 15:21 +0000, Moger, Babu wrote: > Resubmitting it again(Probably last one had some format issues). > > This patch fixes an unbalanced refcount issue. > > Elevating the lock for both kref_put and also for controller node deletion. > Previously, controller deletion was protected but the not the kref_put. This was causing > the other thread to pick up the controller structure which was already kref'd zero. > > This was causing the following BUG_ON and also sometimes panic. > > WARNING: at lib/kref.c:43 kref_get+0x2d/0x30() (Not tainted) > Hardware name: IBM System x3655 -[7985AC1]- > Modules linked in: fuse scsi_dh_rdac autofs4 nfs lockd fscache nfs_acl > auth_rpcgss sunrpc 8021q garp stp llc ipv6 ib_srp(U) scsi_transport_srp > scsi_tgt ib_cm(U) ib_sa(U) ib_uverbs(U) ib_umad(U) mlx4_ib(U) mlx4_core(U) > ib_mthca(U) ib_mad(U) ib_core(U) dm_mirror dm_region_hash dm_log dm_round_robin > dm_multipath uinput bnx2 ses enclosure sg ibmpex ibmaem ipmi_msghandler > serio_raw k8temp hwmon amd64_edac_mod edac_core edac_mce_amd shpchp i2c_piix4 > ext4 mbcache jbd2 sr_mod cdrom sd_mod crc_t10dif sata_svw pata_acpi ata_generic > pata_serverworks aacraid radeon ttm drm_kms_helper drm i2c_algo_bit i2c_core > dm_mod [last unloaded: freq_table] > Pid: 13735, comm: srp_daemon Not tainted 2.6.32-71.el6.x86_64 #1 > Call Trace: > [] warn_slowpath_common+0x87/0xc0 > [] warn_slowpath_null+0x1a/0x20 > [] kref_get+0x2d/0x30 > [] rdac_bus_attach+0x459/0x580 [scsi_dh_rdac] > [] scsi_dh_handler_attach+0x2a/0x80 > [] scsi_dh_notifier+0x9b/0xa0 > [] notifier_call_chain+0x55/0x80 > [] __blocking_notifier_call_chain+0x5a/0x80 > [] blocking_notifier_call_chain+0x16/0x20 > [] device_add+0x515/0x640 > [] ? attribute_container_device_trigger+0xc4/0xe0 > [] scsi_sysfs_add_sdev+0x89/0x2c0 > [] scsi_probe_and_add_lun+0xea6/0xed0 > [] ? scsi_alloc_target+0x292/0x2d0 > [] __scsi_scan_target+0x121/0x750 > [] ? sysfs_create_file+0x26/0x30 > [] ? device_create_file+0x19/0x20 > [] ? attribute_container_add_attrs+0x78/0x90 > [] ? klist_next+0x4c/0xf0 > [] ? transport_configure+0x0/0x20 > [] ? attribute_container_device_trigger+0xc4/0xe0 > [] scsi_scan_target+0xd0/0xe0 > [] srp_create_target+0x75a/0x890 [ib_srp] > [] dev_attr_store+0x20/0x30 > [] sysfs_write_file+0xe5/0x170 > [] vfs_write+0xb8/0x1a0 > [] ? audit_syscall_entry+0x272/0x2a0 > [] sys_write+0x51/0x90 > [] system_call_fastpath+0x16/0x1b > > > Signed-off-by: Babu Moger > Acked-by: Mike Snitzer > --- > --- linux-3.3-rc1-new/drivers/scsi/device_handler/scsi_dh_rdac.c.orig 2012-01-19 17:04:48.000000000 -0600 > +++ linux-3.3-rc1-new/drivers/scsi/device_handler/scsi_dh_rdac.c 2012-02-01 10:50:31.000000000 -0600 > @@ -364,10 +364,7 @@ static void release_controller(struct kr > struct rdac_controller *ctlr; > ctlr = container_of(kref, struct rdac_controller, kref); > > - flush_workqueue(kmpath_rdacd); > - spin_lock(&list_lock); > list_del(&ctlr->node); > - spin_unlock(&list_lock); > kfree(ctlr); > } > > @@ -376,20 +373,17 @@ static struct rdac_controller *get_contr > { > struct rdac_controller *ctlr, *tmp; > > - spin_lock(&list_lock); > - > list_for_each_entry(tmp, &ctlr_list, node) { > if ((memcmp(tmp->array_id, array_id, UNIQUE_ID_LEN) == 0) && > (tmp->index == index) && > (tmp->host == sdev->host)) { > kref_get(&tmp->kref); > - spin_unlock(&list_lock); > return tmp; > } > } > ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC); > if (!ctlr) > - goto done; > + return NULL; > > /* initialize fields of controller */ > memcpy(ctlr->array_id, array_id, UNIQUE_ID_LEN); > @@ -405,8 +399,7 @@ static struct rdac_controller *get_contr > INIT_WORK(&ctlr->ms_work, send_mode_select); > INIT_LIST_HEAD(&ctlr->ms_head); > list_add(&ctlr->node, &ctlr_list); > -done: > - spin_unlock(&list_lock); > + > return ctlr; > } > > @@ -517,9 +510,12 @@ static int initialize_controller(struct > index = 0; > else > index = 1; > + > + spin_lock(&list_lock); > h->ctlr = get_controller(index, array_name, array_id, sdev); > if (!h->ctlr) > err = SCSI_DH_RES_TEMP_UNAVAIL; > + spin_unlock(&list_lock); > } > return err; > } > @@ -906,7 +902,9 @@ static int rdac_bus_attach(struct scsi_d > return 0; > > clean_ctlr: > + spin_lock(&list_lock); > kref_put(&h->ctlr->kref, release_controller); > + spin_unlock(&list_lock); > > failed: > kfree(scsi_dh_data); > @@ -921,14 +919,19 @@ static void rdac_bus_detach( struct scsi > struct rdac_dh_data *h; > unsigned long flags; > > - spin_lock_irqsave(sdev->request_queue->queue_lock, flags); > scsi_dh_data = sdev->scsi_dh_data; > + h = (struct rdac_dh_data *) scsi_dh_data->buf; > + if (h->ctlr && h->ctlr->ms_queued) > + flush_workqueue(kmpath_rdacd); > + > + spin_lock_irqsave(sdev->request_queue->queue_lock, flags); > sdev->scsi_dh_data = NULL; > spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); > > - h = (struct rdac_dh_data *) scsi_dh_data->buf; > + spin_lock(&list_lock); > if (h->ctlr) > kref_put(&h->ctlr->kref, release_controller); > + spin_unlock(&list_lock); > kfree(scsi_dh_data); > module_put(THIS_MODULE); > sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", RDAC_NAME); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/