The following patch introduces an annoying WARN when a device is removed from the SAS topology: [SCSI] libsas: prevent domain rediscovery competing with ata error handling
A sample WARN is as follows: [ 236.842227] WARNING: CPU: 7 PID: 1520 at fs/sysfs/group.c:237 sysfs_remove_group+0x90/0x98 [ 236.850465] Modules linked in: [ 236.853544] [ 236.855045] CPU: 7 PID: 1520 Comm: kworker/u64:4 Tainted: G W 4.9.0-rc1-15310-g3fbc29e-dirty #676 [ 236.865010] Hardware name: Huawei Taishan 2180 /D03, BIOS Estuary v2.3 D03 UEFI 08/17/2016 [ 236.873249] Workqueue: scsi_wq_0 sas_destruct_devices [ 236.878317] task: ffff8027ba31b200 task.stack: ffff8027b9d44000 [ 236.884225] PC is at sysfs_remove_group+0x90/0x98 [ 236.888920] LR is at sysfs_remove_group+0x90/0x98 [ 236.893616] pc : [<ffff000008256df8>] lr : [<ffff000008256df8>] pstate: 60000145 [ 236.900989] sp : ffff8027b9d47bf0 < snip > [ 237.116463] [<ffff000008256df8>] sysfs_remove_group+0x90/0x98 [ 237.122197] [<ffff00000851fe68>] dpm_sysfs_remove+0x58/0x68 [ 237.127758] [<ffff000008513678>] device_del+0x40/0x218 [ 237.132886] [<ffff000008513864>] device_unregister+0x14/0x2c [ 237.138536] [<ffff0000083670c4>] bsg_unregister_queue+0x5c/0xa0 [ 237.144442] [<ffff00000855b984>] sas_rphy_remove+0x44/0x80 [ 237.149915] [<ffff00000855b9d4>] sas_rphy_delete+0x14/0x28 [ 237.155388] [<ffff00000855f9d8>] sas_destruct_devices+0x64/0x98 [ 237.161293] [<ffff0000080d2c1c>] process_one_work+0x128/0x2e4 [ 237.167027] [<ffff0000080d2e30>] worker_thread+0x58/0x434 [ 237.172415] [<ffff0000080d8c24>] kthread+0xd4/0xe8 [ 237.177198] [<ffff000008082e80>] ret_from_fork+0x10/0x50 [ 237.182557] sysfs group 'power' not found for kobject 'end_device-0:0:5' (this can be really huge when an expander is unplugged) The problem is with the process of sas_port and domain_device destruction in domain revalidation. There is a 2-stage process: In domain revalidation (which runs in work queue context), if a domain_device is discovered to be gone, then the following happens: - the domain_device is queued for destruction in a separate work item - the associated sas_port is destroyed immediately This causes a problem in that the sas_port associated with a domain_device is destroyed prior the domain_device: this causes the sysfs WARN. Essentially the "rug has been pulled from underneath". Also, likewise, when a root port is deformed due to loss of signal, we have the same issue. To solve, destroy the sas_port in a separate work item to which we do the domain revalidation with a new discovery event, as follows: - When a domain_device is detected to be gone, the domain_device is queued for destruction in a separate work item. The associated sas_port is also queued for destruction in another separate work item (needs to be queued 2nd) - the domain_device is destroyed - the sas_port is destroyed [similar is done for loss of signal event, in sas_port_deformed()]. Fixes: 87c8331fcf72e501c3a3c0cdc5c [SCSI] libsas: prevent domain rediscovery competing with ata error handling Signed-off-by: John Garry <john.ga...@huawei.com> diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c index 60de662..01d0fe2 100644 --- a/drivers/scsi/libsas/sas_discover.c +++ b/drivers/scsi/libsas/sas_discover.c @@ -361,7 +361,7 @@ static void sas_destruct_devices(struct work_struct *work) clear_bit(DISCE_DESTRUCT, &port->disc.pending); - list_for_each_entry_safe(dev, n, &port->destroy_list, disco_list_node) { + list_for_each_entry_safe(dev, n, &port->dev_destroy_list, disco_list_node) { list_del_init(&dev->disco_list_node); sas_remove_children(&dev->rphy->dev); @@ -383,7 +383,7 @@ void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev) if (!test_and_set_bit(SAS_DEV_DESTROY, &dev->state)) { sas_rphy_unlink(dev->rphy); - list_move_tail(&dev->disco_list_node, &port->destroy_list); + list_move_tail(&dev->disco_list_node, &port->dev_destroy_list); sas_discover_event(dev->port, DISCE_DESTRUCT); } } @@ -525,6 +525,28 @@ static void sas_revalidate_domain(struct work_struct *work) mutex_unlock(&ha->disco_mutex); } +/* ---------- Async Port destruct ---------- */ +static void sas_async_port_destruct(struct work_struct *work) +{ + struct sas_discovery_event *ev = to_sas_discovery_event(work); + struct asd_sas_port *port = ev->port; + struct sas_port *sas_port, *n; + + clear_bit(DISCE_PORT_DESTRUCT, &port->disc.pending); + + list_for_each_entry_safe(sas_port, n, &port->port_destroy_list, destroy_list) { + list_del_init(&port->port_destroy_list); + + sas_port_delete(sas_port); + } +} + +void sas_port_destruct(struct asd_sas_port *port, struct sas_port *sas_port) +{ + list_move_tail(&sas_port->destroy_list, &port->port_destroy_list); + sas_discover_event(port, DISCE_PORT_DESTRUCT); +} + /* ---------- Events ---------- */ static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work *sw) @@ -582,6 +604,7 @@ void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port) [DISCE_SUSPEND] = sas_suspend_devices, [DISCE_RESUME] = sas_resume_devices, [DISCE_DESTRUCT] = sas_destruct_devices, + [DISCE_PORT_DESTRUCT] = sas_async_port_destruct, }; disc->pending = 0; diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c index 022bb6e..f9522a0 100644 --- a/drivers/scsi/libsas/sas_expander.c +++ b/drivers/scsi/libsas/sas_expander.c @@ -1900,10 +1900,11 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent, } memset(phy->attached_sas_addr, 0, SAS_ADDR_SIZE); if (phy->port) { + struct asd_sas_port *port = found->port; sas_port_delete_phy(phy->port, phy->phy); sas_device_set_phy(found, phy->port); if (phy->port->num_phys == 0) - sas_port_delete(phy->port); + sas_port_destruct(port, phy->port); phy->port = NULL; } } diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c index d3c5297..1a32f86 100644 --- a/drivers/scsi/libsas/sas_port.c +++ b/drivers/scsi/libsas/sas_port.c @@ -219,7 +219,7 @@ void sas_deform_port(struct asd_sas_phy *phy, int gone) if (port->num_phys == 1) { sas_unregister_domain_devices(port, gone); - sas_port_delete(port->port); + sas_port_destruct(port, port->port); port->port = NULL; } else { sas_port_delete_phy(port->port, phy->phy); @@ -322,7 +322,8 @@ static void sas_init_port(struct asd_sas_port *port, port->id = i; INIT_LIST_HEAD(&port->dev_list); INIT_LIST_HEAD(&port->disco_list); - INIT_LIST_HEAD(&port->destroy_list); + INIT_LIST_HEAD(&port->dev_destroy_list); + INIT_LIST_HEAD(&port->port_destroy_list); spin_lock_init(&port->phy_list_lock); INIT_LIST_HEAD(&port->phy_list); port->ha = sas_ha; diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c index 60b651b..062c03c 100644 --- a/drivers/scsi/scsi_transport_sas.c +++ b/drivers/scsi/scsi_transport_sas.c @@ -934,6 +934,7 @@ struct sas_port *sas_port_alloc(struct device *parent, int port_id) mutex_init(&port->phy_list_mutex); INIT_LIST_HEAD(&port->phy_list); + INIT_LIST_HEAD(&port->destroy_list); if (scsi_is_sas_expander_device(parent)) { struct sas_rphy *rphy = dev_to_rphy(parent); diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h index dae99d7..a7953c8 100644 --- a/include/scsi/libsas.h +++ b/include/scsi/libsas.h @@ -91,7 +91,8 @@ enum discover_event { DISCE_SUSPEND = 4, DISCE_RESUME = 5, DISCE_DESTRUCT = 6, - DISC_NUM_EVENTS = 7, + DISCE_PORT_DESTRUCT = 7, + DISC_NUM_EVENTS, }; /* ---------- Expander Devices ---------- */ @@ -268,7 +269,8 @@ struct asd_sas_port { spinlock_t dev_list_lock; struct list_head dev_list; struct list_head disco_list; - struct list_head destroy_list; + struct list_head dev_destroy_list; + struct list_head port_destroy_list; enum sas_linkrate linkrate; struct sas_work work; @@ -702,6 +704,7 @@ extern int sas_bios_param(struct scsi_device *, int sas_ex_revalidate_domain(struct domain_device *); void sas_unregister_domain_devices(struct asd_sas_port *port, int gone); +void sas_port_destruct(struct asd_sas_port *port, struct sas_port *sas_port); void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *); int sas_discover_event(struct asd_sas_port *, enum discover_event ev); diff --git a/include/scsi/scsi_transport_sas.h b/include/scsi/scsi_transport_sas.h index 73d8709..b495aac 100644 --- a/include/scsi/scsi_transport_sas.h +++ b/include/scsi/scsi_transport_sas.h @@ -154,6 +154,7 @@ struct sas_port { struct mutex phy_list_mutex; struct list_head phy_list; + struct list_head destroy_list; /* only used by libsas */ }; #define dev_to_sas_port(d) \ -- 1.9.1