diff mbox series

[Xenial,SRU,CVE-2017-18232,1/1] scsi: libsas: direct call probe and destruct

Message ID 20190927161923.24915-2-connor.kuehl@canonical.com
State New
Headers show
Series SAS DoS | expand

Commit Message

Connor Kuehl Sept. 27, 2019, 4:19 p.m. UTC 
From: Jason Yan <yanaijie@huawei.com>

CVE-2017-18232

In commit 87c8331fcf72 ("[SCSI] libsas: prevent domain rediscovery
competing with ata error handling") introduced disco mutex to prevent
rediscovery competing with ata error handling and put the whole
revalidation in the mutex. But the rphy add/remove needs to wait for the
error handling which also grabs the disco mutex. This may leads to dead
lock.So the probe and destruct event were introduce to do the rphy
add/remove asynchronously and out of the lock.

The asynchronously processed workers makes the whole discovery process
not atomic, the other events may interrupt the process. For example,
if a loss of signal event inserted before the probe event, the
sas_deform_port() is called and the port will be deleted.

And sas_port_delete() may run before the destruct event, but the
port-x:x is the top parent of end device or expander. This leads to
a kernel WARNING such as:

[   82.042979] sysfs group 'power' not found for kobject 'phy-1:0:22'
[   82.042983] ------------[ cut here ]------------
[   82.042986] WARNING: CPU: 54 PID: 1714 at fs/sysfs/group.c:237
sysfs_remove_group+0x94/0xa0
[   82.043059] Call trace:
[   82.043082] [<ffff0000082e7624>] sysfs_remove_group+0x94/0xa0
[   82.043085] [<ffff00000864e320>] dpm_sysfs_remove+0x60/0x70
[   82.043086] [<ffff00000863ee10>] device_del+0x138/0x308
[   82.043089] [<ffff00000869a2d0>] sas_phy_delete+0x38/0x60
[   82.043091] [<ffff00000869a86c>] do_sas_phy_delete+0x6c/0x80
[   82.043093] [<ffff00000863dc20>] device_for_each_child+0x58/0xa0
[   82.043095] [<ffff000008696f80>] sas_remove_children+0x40/0x50
[   82.043100] [<ffff00000869d1bc>] sas_destruct_devices+0x64/0xa0
[   82.043102] [<ffff0000080e93bc>] process_one_work+0x1fc/0x4b0
[   82.043104] [<ffff0000080e96c0>] worker_thread+0x50/0x490
[   82.043105] [<ffff0000080f0364>] kthread+0xfc/0x128
[   82.043107] [<ffff0000080836c0>] ret_from_fork+0x10/0x50

Make probe and destruct a direct call in the disco and revalidate function,
but put them outside the lock. The whole discovery or revalidate won't
be interrupted by other events. And the DISCE_PROBE and DISCE_DESTRUCT
event are deleted as a result of the direct call.

Introduce a new list to destruct the sas_port and put the port delete after
the destruct. This makes sure the right order of destroying the sysfs
kobject and fix the warning above.

In sas_ex_revalidate_domain() have a loop to find all broadcasted
device, and sometimes we have a chance to find the same expander twice.
Because the sas_port will be deleted at the end of the whole revalidate
process, sas_port with the same name cannot be added before this.
Otherwise the sysfs will complain of creating duplicate filename. Since
the LLDD will send broadcast for every device change, we can only
process one expander's revalidation.

[mkp: kbuild test robot warning]

Signed-off-by: Jason Yan <yanaijie@huawei.com>
CC: John Garry <john.garry@huawei.com>
CC: Johannes Thumshirn <jthumshirn@suse.de>
CC: Ewan Milne <emilne@redhat.com>
CC: Christoph Hellwig <hch@lst.de>
CC: Tomas Henzl <thenzl@redhat.com>
CC: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(backported from commit 0558f33c06bb910e2879e355192227a8e8f0219d)
[ Connor Kuehl: The hunk that removed variants from 'enum
  discover_event' required manual placement. I did take the liberty of
  removing the hardcoded enum values from this enum as is done in
  upstream commit 0d78f969b10f "scsi: libsas: remove the numbering for
  each event enum" but only for this enum to reduce confusion over
  renumbering. It seemed overkill to take in the entire patch alongside
  this backport. ]
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
---
 drivers/scsi/libsas/sas_ata.c      |  1 -
 drivers/scsi/libsas/sas_discover.c | 32 +++++++++++++++++-------------
 drivers/scsi/libsas/sas_expander.c |  8 +++-----
 drivers/scsi/libsas/sas_internal.h |  1 +
 drivers/scsi/libsas/sas_port.c     |  3 +++
 include/scsi/libsas.h              | 13 ++++++------
 include/scsi/scsi_transport_sas.h  |  1 +
 7 files changed, 32 insertions(+), 27 deletions(-)

Comments

Tyler Hicks Sept. 30, 2019, 3:44 p.m. UTC | #1 
On 2019-09-27 09:19:23, Connor Kuehl wrote:
> From: Jason Yan <yanaijie@huawei.com>
> 
> CVE-2017-18232
> 
> In commit 87c8331fcf72 ("[SCSI] libsas: prevent domain rediscovery
> competing with ata error handling") introduced disco mutex to prevent
> rediscovery competing with ata error handling and put the whole
> revalidation in the mutex. But the rphy add/remove needs to wait for the
> error handling which also grabs the disco mutex. This may leads to dead
> lock.So the probe and destruct event were introduce to do the rphy
> add/remove asynchronously and out of the lock.
> 
> The asynchronously processed workers makes the whole discovery process
> not atomic, the other events may interrupt the process. For example,
> if a loss of signal event inserted before the probe event, the
> sas_deform_port() is called and the port will be deleted.
> 
> And sas_port_delete() may run before the destruct event, but the
> port-x:x is the top parent of end device or expander. This leads to
> a kernel WARNING such as:
> 
> [   82.042979] sysfs group 'power' not found for kobject 'phy-1:0:22'
> [   82.042983] ------------[ cut here ]------------
> [   82.042986] WARNING: CPU: 54 PID: 1714 at fs/sysfs/group.c:237
> sysfs_remove_group+0x94/0xa0
> [   82.043059] Call trace:
> [   82.043082] [<ffff0000082e7624>] sysfs_remove_group+0x94/0xa0
> [   82.043085] [<ffff00000864e320>] dpm_sysfs_remove+0x60/0x70
> [   82.043086] [<ffff00000863ee10>] device_del+0x138/0x308
> [   82.043089] [<ffff00000869a2d0>] sas_phy_delete+0x38/0x60
> [   82.043091] [<ffff00000869a86c>] do_sas_phy_delete+0x6c/0x80
> [   82.043093] [<ffff00000863dc20>] device_for_each_child+0x58/0xa0
> [   82.043095] [<ffff000008696f80>] sas_remove_children+0x40/0x50
> [   82.043100] [<ffff00000869d1bc>] sas_destruct_devices+0x64/0xa0
> [   82.043102] [<ffff0000080e93bc>] process_one_work+0x1fc/0x4b0
> [   82.043104] [<ffff0000080e96c0>] worker_thread+0x50/0x490
> [   82.043105] [<ffff0000080f0364>] kthread+0xfc/0x128
> [   82.043107] [<ffff0000080836c0>] ret_from_fork+0x10/0x50
> 
> Make probe and destruct a direct call in the disco and revalidate function,
> but put them outside the lock. The whole discovery or revalidate won't
> be interrupted by other events. And the DISCE_PROBE and DISCE_DESTRUCT
> event are deleted as a result of the direct call.
> 
> Introduce a new list to destruct the sas_port and put the port delete after
> the destruct. This makes sure the right order of destroying the sysfs
> kobject and fix the warning above.
> 
> In sas_ex_revalidate_domain() have a loop to find all broadcasted
> device, and sometimes we have a chance to find the same expander twice.
> Because the sas_port will be deleted at the end of the whole revalidate
> process, sas_port with the same name cannot be added before this.
> Otherwise the sysfs will complain of creating duplicate filename. Since
> the LLDD will send broadcast for every device change, we can only
> process one expander's revalidation.
> 
> [mkp: kbuild test robot warning]
> 
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> CC: John Garry <john.garry@huawei.com>
> CC: Johannes Thumshirn <jthumshirn@suse.de>
> CC: Ewan Milne <emilne@redhat.com>
> CC: Christoph Hellwig <hch@lst.de>
> CC: Tomas Henzl <thenzl@redhat.com>
> CC: Dan Williams <dan.j.williams@intel.com>
> Reviewed-by: Hannes Reinecke <hare@suse.com>
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> (backported from commit 0558f33c06bb910e2879e355192227a8e8f0219d)
> [ Connor Kuehl: The hunk that removed variants from 'enum
>   discover_event' required manual placement. I did take the liberty of
>   removing the hardcoded enum values from this enum as is done in
>   upstream commit 0d78f969b10f "scsi: libsas: remove the numbering for
>   each event enum" but only for this enum to reduce confusion over
>   renumbering. It seemed overkill to take in the entire patch alongside
>   this backport. ]
> Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>

The changes to the discover_event enum look fine to me.

Acked-by: Tyler Hicks <tyhicks@canonical.com>

Thanks!

Tyler

> ---
>  drivers/scsi/libsas/sas_ata.c      |  1 -
>  drivers/scsi/libsas/sas_discover.c | 32 +++++++++++++++++-------------
>  drivers/scsi/libsas/sas_expander.c |  8 +++-----
>  drivers/scsi/libsas/sas_internal.h |  1 +
>  drivers/scsi/libsas/sas_port.c     |  3 +++
>  include/scsi/libsas.h              | 13 ++++++------
>  include/scsi/scsi_transport_sas.h  |  1 +
>  7 files changed, 32 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
> index 6f5e2720ffad..e018e76b156b 100644
> --- a/drivers/scsi/libsas/sas_ata.c
> +++ b/drivers/scsi/libsas/sas_ata.c
> @@ -732,7 +732,6 @@ int sas_discover_sata(struct domain_device *dev)
>  	if (res)
>  		return res;
>  
> -	sas_discover_event(dev->port, DISCE_PROBE);
>  	return 0;
>  }
>  
> diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
> index 60de66252fa2..487d7345f515 100644
> --- a/drivers/scsi/libsas/sas_discover.c
> +++ b/drivers/scsi/libsas/sas_discover.c
> @@ -212,13 +212,9 @@ void sas_notify_lldd_dev_gone(struct domain_device *dev)
>  	}
>  }
>  
> -static void sas_probe_devices(struct work_struct *work)
> +static void sas_probe_devices(struct asd_sas_port *port)
>  {
>  	struct domain_device *dev, *n;
> -	struct sas_discovery_event *ev = to_sas_discovery_event(work);
> -	struct asd_sas_port *port = ev->port;
> -
> -	clear_bit(DISCE_PROBE, &port->disc.pending);
>  
>  	/* devices must be domain members before link recovery and probe */
>  	list_for_each_entry(dev, &port->disco_list, disco_list_node) {
> @@ -294,7 +290,6 @@ int sas_discover_end_dev(struct domain_device *dev)
>  	res = sas_notify_lldd_dev_found(dev);
>  	if (res)
>  		return res;
> -	sas_discover_event(dev->port, DISCE_PROBE);
>  
>  	return 0;
>  }
> @@ -353,13 +348,9 @@ static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
>  	sas_put_device(dev);
>  }
>  
> -static void sas_destruct_devices(struct work_struct *work)
> +void sas_destruct_devices(struct asd_sas_port *port)
>  {
>  	struct domain_device *dev, *n;
> -	struct sas_discovery_event *ev = to_sas_discovery_event(work);
> -	struct asd_sas_port *port = ev->port;
> -
> -	clear_bit(DISCE_DESTRUCT, &port->disc.pending);
>  
>  	list_for_each_entry_safe(dev, n, &port->destroy_list, disco_list_node) {
>  		list_del_init(&dev->disco_list_node);
> @@ -370,6 +361,16 @@ static void sas_destruct_devices(struct work_struct *work)
>  	}
>  }
>  
> +static void sas_destruct_ports(struct asd_sas_port *port)
> +{
> +	struct sas_port *sas_port, *p;
> +
> +	list_for_each_entry_safe(sas_port, p, &port->sas_port_del_list, del_list) {
> +		list_del_init(&sas_port->del_list);
> +		sas_port_delete(sas_port);
> +	}
> +}
> +
>  void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
>  {
>  	if (!test_bit(SAS_DEV_DESTROY, &dev->state) &&
> @@ -384,7 +385,6 @@ 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);
> -		sas_discover_event(dev->port, DISCE_DESTRUCT);
>  	}
>  }
>  
> @@ -490,6 +490,8 @@ static void sas_discover_domain(struct work_struct *work)
>  		port->port_dev = NULL;
>  	}
>  
> +	sas_probe_devices(port);
> +
>  	SAS_DPRINTK("DONE DISCOVERY on port %d, pid:%d, result:%d\n", port->id,
>  		    task_pid_nr(current), error);
>  }
> @@ -523,6 +525,10 @@ static void sas_revalidate_domain(struct work_struct *work)
>  		    port->id, task_pid_nr(current), res);
>   out:
>  	mutex_unlock(&ha->disco_mutex);
> +
> +	sas_destruct_devices(port);
> +	sas_destruct_ports(port);
> +	sas_probe_devices(port);
>  }
>  
>  /* ---------- Events ---------- */
> @@ -578,10 +584,8 @@ void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
>  	static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
>  		[DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
>  		[DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
> -		[DISCE_PROBE] = sas_probe_devices,
>  		[DISCE_SUSPEND] = sas_suspend_devices,
>  		[DISCE_RESUME] = sas_resume_devices,
> -		[DISCE_DESTRUCT] = sas_destruct_devices,
>  	};
>  
>  	disc->pending = 0;
> diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
> index 400eee9d7783..3d104be4076e 100644
> --- a/drivers/scsi/libsas/sas_expander.c
> +++ b/drivers/scsi/libsas/sas_expander.c
> @@ -1908,7 +1908,8 @@ static void sas_unregister_devs_sas_addr(struct domain_device *parent,
>  		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);
> +			list_add_tail(&phy->port->del_list,
> +				&parent->port->sas_port_del_list);
>  		phy->port = NULL;
>  	}
>  }
> @@ -2121,7 +2122,7 @@ int sas_ex_revalidate_domain(struct domain_device *port_dev)
>  	struct domain_device *dev = NULL;
>  
>  	res = sas_find_bcast_dev(port_dev, &dev);
> -	while (res == 0 && dev) {
> +	if (res == 0 && dev) {
>  		struct expander_device *ex = &dev->ex_dev;
>  		int i = 0, phy_id;
>  
> @@ -2133,9 +2134,6 @@ int sas_ex_revalidate_domain(struct domain_device *port_dev)
>  			res = sas_rediscover(dev, phy_id);
>  			i = phy_id + 1;
>  		} while (i < ex->num_phys);
> -
> -		dev = NULL;
> -		res = sas_find_bcast_dev(port_dev, &dev);
>  	}
>  	return res;
>  }
> diff --git a/drivers/scsi/libsas/sas_internal.h b/drivers/scsi/libsas/sas_internal.h
> index 9cf0bc260b0e..2cbbd113d898 100644
> --- a/drivers/scsi/libsas/sas_internal.h
> +++ b/drivers/scsi/libsas/sas_internal.h
> @@ -98,6 +98,7 @@ int sas_try_ata_reset(struct asd_sas_phy *phy);
>  void sas_hae_reset(struct work_struct *work);
>  
>  void sas_free_device(struct kref *kref);
> +void sas_destruct_devices(struct asd_sas_port *port);
>  
>  #ifdef CONFIG_SCSI_SAS_HOST_SMP
>  extern int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
> diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
> index d3c5297c6c89..5d3244c8f280 100644
> --- a/drivers/scsi/libsas/sas_port.c
> +++ b/drivers/scsi/libsas/sas_port.c
> @@ -66,6 +66,7 @@ static void sas_resume_port(struct asd_sas_phy *phy)
>  		rc = sas_notify_lldd_dev_found(dev);
>  		if (rc) {
>  			sas_unregister_dev(port, dev);
> +			sas_destruct_devices(port);
>  			continue;
>  		}
>  
> @@ -219,6 +220,7 @@ void sas_deform_port(struct asd_sas_phy *phy, int gone)
>  
>  	if (port->num_phys == 1) {
>  		sas_unregister_domain_devices(port, gone);
> +		sas_destruct_devices(port);
>  		sas_port_delete(port->port);
>  		port->port = NULL;
>  	} else {
> @@ -323,6 +325,7 @@ static void sas_init_port(struct asd_sas_port *port,
>  	INIT_LIST_HEAD(&port->dev_list);
>  	INIT_LIST_HEAD(&port->disco_list);
>  	INIT_LIST_HEAD(&port->destroy_list);
> +	INIT_LIST_HEAD(&port->sas_port_del_list);
>  	spin_lock_init(&port->phy_list_lock);
>  	INIT_LIST_HEAD(&port->phy_list);
>  	port->ha = sas_ha;
> diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
> index 706a7017885c..c9226edaca08 100644
> --- a/include/scsi/libsas.h
> +++ b/include/scsi/libsas.h
> @@ -85,13 +85,11 @@ enum phy_event {
>  
>  enum discover_event {
>  	DISCE_DISCOVER_DOMAIN   = 0U,
> -	DISCE_REVALIDATE_DOMAIN = 1,
> -	DISCE_PORT_GONE         = 2,
> -	DISCE_PROBE		= 3,
> -	DISCE_SUSPEND		= 4,
> -	DISCE_RESUME		= 5,
> -	DISCE_DESTRUCT		= 6,
> -	DISC_NUM_EVENTS		= 7,
> +	DISCE_REVALIDATE_DOMAIN,
> +	DISCE_PORT_GONE,
> +	DISCE_SUSPEND,
> +	DISCE_RESUME,
> +	DISC_NUM_EVENTS,
>  };
>  
>  /* ---------- Expander Devices ---------- */
> @@ -269,6 +267,7 @@ struct asd_sas_port {
>  	struct list_head dev_list;
>  	struct list_head disco_list;
>  	struct list_head destroy_list;
> +	struct list_head sas_port_del_list;
>  	enum   sas_linkrate linkrate;
>  
>  	struct sas_work work;
> diff --git a/include/scsi/scsi_transport_sas.h b/include/scsi/scsi_transport_sas.h
> index 31ae074dad9d..d088d450de61 100644
> --- a/include/scsi/scsi_transport_sas.h
> +++ b/include/scsi/scsi_transport_sas.h
> @@ -160,6 +160,7 @@ struct sas_port {
>  
>  	struct mutex		phy_list_mutex;
>  	struct list_head	phy_list;
> +	struct list_head	del_list; /* libsas only */
>  };
>  
>  #define dev_to_sas_port(d) \
> -- 
> 2.17.1
> 
> 
> -- 
> kernel-team mailing list
> kernel-team@lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
diff mbox series

Patch

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 6f5e2720ffad..e018e76b156b 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -732,7 +732,6 @@  int sas_discover_sata(struct domain_device *dev)
 	if (res)
 		return res;
 
-	sas_discover_event(dev->port, DISCE_PROBE);
 	return 0;
 }
 
diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 60de66252fa2..487d7345f515 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -212,13 +212,9 @@  void sas_notify_lldd_dev_gone(struct domain_device *dev)
 	}
 }
 
-static void sas_probe_devices(struct work_struct *work)
+static void sas_probe_devices(struct asd_sas_port *port)
 {
 	struct domain_device *dev, *n;
-	struct sas_discovery_event *ev = to_sas_discovery_event(work);
-	struct asd_sas_port *port = ev->port;
-
-	clear_bit(DISCE_PROBE, &port->disc.pending);
 
 	/* devices must be domain members before link recovery and probe */
 	list_for_each_entry(dev, &port->disco_list, disco_list_node) {
@@ -294,7 +290,6 @@  int sas_discover_end_dev(struct domain_device *dev)
 	res = sas_notify_lldd_dev_found(dev);
 	if (res)
 		return res;
-	sas_discover_event(dev->port, DISCE_PROBE);
 
 	return 0;
 }
@@ -353,13 +348,9 @@  static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
 	sas_put_device(dev);
 }
 
-static void sas_destruct_devices(struct work_struct *work)
+void sas_destruct_devices(struct asd_sas_port *port)
 {
 	struct domain_device *dev, *n;
-	struct sas_discovery_event *ev = to_sas_discovery_event(work);
-	struct asd_sas_port *port = ev->port;
-
-	clear_bit(DISCE_DESTRUCT, &port->disc.pending);
 
 	list_for_each_entry_safe(dev, n, &port->destroy_list, disco_list_node) {
 		list_del_init(&dev->disco_list_node);
@@ -370,6 +361,16 @@  static void sas_destruct_devices(struct work_struct *work)
 	}
 }
 
+static void sas_destruct_ports(struct asd_sas_port *port)
+{
+	struct sas_port *sas_port, *p;
+
+	list_for_each_entry_safe(sas_port, p, &port->sas_port_del_list, del_list) {
+		list_del_init(&sas_port->del_list);
+		sas_port_delete(sas_port);
+	}
+}
+
 void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
 {
 	if (!test_bit(SAS_DEV_DESTROY, &dev->state) &&
@@ -384,7 +385,6 @@  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);
-		sas_discover_event(dev->port, DISCE_DESTRUCT);
 	}
 }
 
@@ -490,6 +490,8 @@  static void sas_discover_domain(struct work_struct *work)
 		port->port_dev = NULL;
 	}
 
+	sas_probe_devices(port);
+
 	SAS_DPRINTK("DONE DISCOVERY on port %d, pid:%d, result:%d\n", port->id,
 		    task_pid_nr(current), error);
 }
@@ -523,6 +525,10 @@  static void sas_revalidate_domain(struct work_struct *work)
 		    port->id, task_pid_nr(current), res);
  out:
 	mutex_unlock(&ha->disco_mutex);
+
+	sas_destruct_devices(port);
+	sas_destruct_ports(port);
+	sas_probe_devices(port);
 }
 
 /* ---------- Events ---------- */
@@ -578,10 +584,8 @@  void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
 	static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
 		[DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
 		[DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
-		[DISCE_PROBE] = sas_probe_devices,
 		[DISCE_SUSPEND] = sas_suspend_devices,
 		[DISCE_RESUME] = sas_resume_devices,
-		[DISCE_DESTRUCT] = sas_destruct_devices,
 	};
 
 	disc->pending = 0;
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 400eee9d7783..3d104be4076e 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -1908,7 +1908,8 @@  static void sas_unregister_devs_sas_addr(struct domain_device *parent,
 		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);
+			list_add_tail(&phy->port->del_list,
+				&parent->port->sas_port_del_list);
 		phy->port = NULL;
 	}
 }
@@ -2121,7 +2122,7 @@  int sas_ex_revalidate_domain(struct domain_device *port_dev)
 	struct domain_device *dev = NULL;
 
 	res = sas_find_bcast_dev(port_dev, &dev);
-	while (res == 0 && dev) {
+	if (res == 0 && dev) {
 		struct expander_device *ex = &dev->ex_dev;
 		int i = 0, phy_id;
 
@@ -2133,9 +2134,6 @@  int sas_ex_revalidate_domain(struct domain_device *port_dev)
 			res = sas_rediscover(dev, phy_id);
 			i = phy_id + 1;
 		} while (i < ex->num_phys);
-
-		dev = NULL;
-		res = sas_find_bcast_dev(port_dev, &dev);
 	}
 	return res;
 }
diff --git a/drivers/scsi/libsas/sas_internal.h b/drivers/scsi/libsas/sas_internal.h
index 9cf0bc260b0e..2cbbd113d898 100644
--- a/drivers/scsi/libsas/sas_internal.h
+++ b/drivers/scsi/libsas/sas_internal.h
@@ -98,6 +98,7 @@  int sas_try_ata_reset(struct asd_sas_phy *phy);
 void sas_hae_reset(struct work_struct *work);
 
 void sas_free_device(struct kref *kref);
+void sas_destruct_devices(struct asd_sas_port *port);
 
 #ifdef CONFIG_SCSI_SAS_HOST_SMP
 extern int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index d3c5297c6c89..5d3244c8f280 100644
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -66,6 +66,7 @@  static void sas_resume_port(struct asd_sas_phy *phy)
 		rc = sas_notify_lldd_dev_found(dev);
 		if (rc) {
 			sas_unregister_dev(port, dev);
+			sas_destruct_devices(port);
 			continue;
 		}
 
@@ -219,6 +220,7 @@  void sas_deform_port(struct asd_sas_phy *phy, int gone)
 
 	if (port->num_phys == 1) {
 		sas_unregister_domain_devices(port, gone);
+		sas_destruct_devices(port);
 		sas_port_delete(port->port);
 		port->port = NULL;
 	} else {
@@ -323,6 +325,7 @@  static void sas_init_port(struct asd_sas_port *port,
 	INIT_LIST_HEAD(&port->dev_list);
 	INIT_LIST_HEAD(&port->disco_list);
 	INIT_LIST_HEAD(&port->destroy_list);
+	INIT_LIST_HEAD(&port->sas_port_del_list);
 	spin_lock_init(&port->phy_list_lock);
 	INIT_LIST_HEAD(&port->phy_list);
 	port->ha = sas_ha;
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 706a7017885c..c9226edaca08 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -85,13 +85,11 @@  enum phy_event {
 
 enum discover_event {
 	DISCE_DISCOVER_DOMAIN   = 0U,
-	DISCE_REVALIDATE_DOMAIN = 1,
-	DISCE_PORT_GONE         = 2,
-	DISCE_PROBE		= 3,
-	DISCE_SUSPEND		= 4,
-	DISCE_RESUME		= 5,
-	DISCE_DESTRUCT		= 6,
-	DISC_NUM_EVENTS		= 7,
+	DISCE_REVALIDATE_DOMAIN,
+	DISCE_PORT_GONE,
+	DISCE_SUSPEND,
+	DISCE_RESUME,
+	DISC_NUM_EVENTS,
 };
 
 /* ---------- Expander Devices ---------- */
@@ -269,6 +267,7 @@  struct asd_sas_port {
 	struct list_head dev_list;
 	struct list_head disco_list;
 	struct list_head destroy_list;
+	struct list_head sas_port_del_list;
 	enum   sas_linkrate linkrate;
 
 	struct sas_work work;
diff --git a/include/scsi/scsi_transport_sas.h b/include/scsi/scsi_transport_sas.h
index 31ae074dad9d..d088d450de61 100644
--- a/include/scsi/scsi_transport_sas.h
+++ b/include/scsi/scsi_transport_sas.h
@@ -160,6 +160,7 @@  struct sas_port {
 
 	struct mutex		phy_list_mutex;
 	struct list_head	phy_list;
+	struct list_head	del_list; /* libsas only */
 };
 
 #define dev_to_sas_port(d) \