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Subject[PATCH v4 10/11] libsas: direct call probe and destruct
Date
In commit 87c8331f ([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.

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>
---
drivers/scsi/libsas/sas_ata.c | 1 -
drivers/scsi/libsas/sas_discover.c | 34 ++++++++++++++++++++--------------
drivers/scsi/libsas/sas_expander.c | 2 +-
drivers/scsi/libsas/sas_internal.h | 1 +
drivers/scsi/libsas/sas_port.c | 3 +++
include/scsi/libsas.h | 3 +--
include/scsi/scsi_transport_sas.h | 1 +
7 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 87f5e694..dbe8c5e 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -729,7 +729,6 @@ 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 14f714d..d5f5b58 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)
}
}

+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 +525,12 @@ 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 +586,8 @@ 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 570b2cb..b107a44 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -1903,7 +1903,7 @@ 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;
}
}
diff --git a/drivers/scsi/libsas/sas_internal.h b/drivers/scsi/libsas/sas_internal.h
index 29a7a60..dd74ed5 100644
--- a/drivers/scsi/libsas/sas_internal.h
+++ b/drivers/scsi/libsas/sas_internal.h
@@ -99,6 +99,7 @@ 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);

extern const work_func_t sas_phy_event_fns[PHY_NUM_EVENTS];
extern const work_func_t sas_port_event_fns[PORT_NUM_EVENTS];
diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index 64722f4..f07e55d 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;
}

@@ -220,6 +221,7 @@ 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 {
@@ -317,6 +319,7 @@ 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 d1ab157..cb3b010 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -82,10 +82,8 @@ enum phy_event {
enum discover_event {
DISCE_DISCOVER_DOMAIN = 0U,
DISCE_REVALIDATE_DOMAIN,
- DISCE_PROBE,
DISCE_SUSPEND,
DISCE_RESUME,
- DISCE_DESTRUCT,
DISC_NUM_EVENTS,
};

@@ -262,6 +260,7 @@ 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 73d8709..2cf88fa 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 del_list; /* libsas only */
};

#define dev_to_sas_port(d) \
--
2.5.0
\
 
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