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authorPetr Tesarik <ptesarik@suse.cz>2019-06-24 09:36:42 +0200
committerPetr Tesarik <ptesarik@suse.cz>2019-06-24 09:37:05 +0200
commit4401d3bae18e8ded20a9ba47870d36baa8ff29ec (patch)
tree8cf046f009113ef68129b8de15358503edfc6155
parentb36c370c06996d6dd07b817fecb8c7b0253f75d4 (diff)
scsi: zfcp: fix to prevent port_remove with pure auto scan LUNs
(only sdevs) (bsc#1051510).
-rw-r--r--patches.fixes/scsi-zfcp-fix-to-prevent-port_remove-with-pure-auto-scan-luns-only-sdevs184
-rw-r--r--series.conf1
2 files changed, 185 insertions, 0 deletions
diff --git a/patches.fixes/scsi-zfcp-fix-to-prevent-port_remove-with-pure-auto-scan-luns-only-sdevs b/patches.fixes/scsi-zfcp-fix-to-prevent-port_remove-with-pure-auto-scan-luns-only-sdevs
new file mode 100644
index 0000000000..1ee44c3892
--- /dev/null
+++ b/patches.fixes/scsi-zfcp-fix-to-prevent-port_remove-with-pure-auto-scan-luns-only-sdevs
@@ -0,0 +1,184 @@
+From: Steffen Maier <maier@linux.ibm.com>
+Date: Thu, 23 May 2019 15:23:46 +0200
+Subject: scsi: zfcp: fix to prevent port_remove with pure auto scan LUNs (only
+ sdevs)
+Git-commit: ef4021fe5fd77ced0323cede27979d80a56211ca
+Patch-mainline: v5.2-rc1
+References: bsc#1051510
+
+When the user tries to remove a zfcp port via sysfs, we only rejected it if
+there are zfcp unit children under the port. With purely automatically
+scanned LUNs there are no zfcp units but only SCSI devices. In such cases,
+the port_remove erroneously continued. We close the port and this
+implicitly closes all LUNs under the port. The SCSI devices survive with
+their private zfcp_scsi_dev still holding a reference to the "removed"
+zfcp_port (still allocated but invisible in sysfs) [zfcp_get_port_by_wwpn
+in zfcp_scsi_slave_alloc]. This is not a problem as long as the fc_rport
+stays blocked. Once (auto) port scan brings back the removed port, we
+unblock its fc_rport again by design. However, there is no mechanism that
+would recover (open) the LUNs under the port (no "ersfs_3" without
+zfcp_unit [zfcp_erp_strategy_followup_success]). Any pending or new I/O to
+such LUN leads to repeated:
+
+ Done: NEEDS_RETRY Result: hostbyte=DID_IMM_RETRY driverbyte=DRIVER_OK
+
+See also v4.10 commit 6f2ce1c6af37 ("scsi: zfcp: fix rport unblock race
+with LUN recovery"). Even a manual LUN recovery
+(echo 0 > /sys/bus/scsi/devices/H:C:T:L/zfcp_failed)
+does not help, as the LUN links to the old "removed" port which remains
+to lack ZFCP_STATUS_COMMON_RUNNING [zfcp_erp_required_act].
+The only workaround is to first ensure that the fc_rport is blocked
+(e.g. port_remove again in case it was re-discovered by (auto) port scan),
+then delete the SCSI devices, and finally re-discover by (auto) port scan.
+The port scan includes an fc_rport unblock, which in turn triggers
+a new scan on the scsi target to freshly get new pure auto scan LUNs.
+
+Fix this by rejecting port_remove also if there are SCSI devices
+(even without any zfcp_unit) under this port. Re-use mechanics from v3.7
+commit d99b601b6338 ("[SCSI] zfcp: restore refcount check on port_remove").
+However, we have to give up zfcp_sysfs_port_units_mutex earlier in unit_add
+to prevent a deadlock with scsi_host scan taking shost->scan_mutex first
+and then zfcp_sysfs_port_units_mutex now in our zfcp_scsi_slave_alloc().
+
+Signed-off-by: Steffen Maier <maier@linux.ibm.com>
+Fixes: b62a8d9b45b9 ("[SCSI] zfcp: Use SCSI device data zfcp scsi dev instead of zfcp unit")
+Fixes: f8210e34887e ("[SCSI] zfcp: Allow midlayer to scan for LUNs when running in NPIV mode")
+Cc: <stable@vger.kernel.org> #2.6.37+
+Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
+Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
+Acked-by: Petr Tesarik <ptesarik@suse.com>
+---
+ drivers/s390/scsi/zfcp_ext.h | 1
+ drivers/s390/scsi/zfcp_scsi.c | 9 ++++++
+ drivers/s390/scsi/zfcp_sysfs.c | 54 ++++++++++++++++++++++++++++++++++++-----
+ drivers/s390/scsi/zfcp_unit.c | 8 +++++-
+ 4 files changed, 65 insertions(+), 7 deletions(-)
+
+--- a/drivers/s390/scsi/zfcp_ext.h
++++ b/drivers/s390/scsi/zfcp_ext.h
+@@ -161,6 +161,7 @@ extern const struct attribute_group *zfc
+ extern struct mutex zfcp_sysfs_port_units_mutex;
+ extern struct device_attribute *zfcp_sysfs_sdev_attrs[];
+ extern struct device_attribute *zfcp_sysfs_shost_attrs[];
++bool zfcp_sysfs_port_is_removing(const struct zfcp_port *const port);
+
+ /* zfcp_unit.c */
+ extern int zfcp_unit_add(struct zfcp_port *, u64);
+--- a/drivers/s390/scsi/zfcp_scsi.c
++++ b/drivers/s390/scsi/zfcp_scsi.c
+@@ -124,6 +124,15 @@ static int zfcp_scsi_slave_alloc(struct
+
+ zfcp_sdev->erp_action.port = port;
+
++ mutex_lock(&zfcp_sysfs_port_units_mutex);
++ if (zfcp_sysfs_port_is_removing(port)) {
++ /* port is already gone */
++ mutex_unlock(&zfcp_sysfs_port_units_mutex);
++ put_device(&port->dev); /* undo zfcp_get_port_by_wwpn() */
++ return -ENXIO;
++ }
++ mutex_unlock(&zfcp_sysfs_port_units_mutex);
++
+ unit = zfcp_unit_find(port, zfcp_scsi_dev_lun(sdev));
+ if (unit)
+ put_device(&unit->dev);
+--- a/drivers/s390/scsi/zfcp_sysfs.c
++++ b/drivers/s390/scsi/zfcp_sysfs.c
+@@ -237,6 +237,53 @@ static ZFCP_DEV_ATTR(adapter, port_resca
+
+ DEFINE_MUTEX(zfcp_sysfs_port_units_mutex);
+
++static void zfcp_sysfs_port_set_removing(struct zfcp_port *const port)
++{
++ lockdep_assert_held(&zfcp_sysfs_port_units_mutex);
++ atomic_set(&port->units, -1);
++}
++
++bool zfcp_sysfs_port_is_removing(const struct zfcp_port *const port)
++{
++ lockdep_assert_held(&zfcp_sysfs_port_units_mutex);
++ return atomic_read(&port->units) == -1;
++}
++
++static bool zfcp_sysfs_port_in_use(struct zfcp_port *const port)
++{
++ struct zfcp_adapter *const adapter = port->adapter;
++ unsigned long flags;
++ struct scsi_device *sdev;
++ bool in_use = true;
++
++ mutex_lock(&zfcp_sysfs_port_units_mutex);
++ if (atomic_read(&port->units) > 0)
++ goto unlock_port_units_mutex; /* zfcp_unit(s) under port */
++
++ spin_lock_irqsave(adapter->scsi_host->host_lock, flags);
++ __shost_for_each_device(sdev, adapter->scsi_host) {
++ const struct zfcp_scsi_dev *zsdev = sdev_to_zfcp(sdev);
++
++ if (sdev->sdev_state == SDEV_DEL ||
++ sdev->sdev_state == SDEV_CANCEL)
++ continue;
++ if (zsdev->port != port)
++ continue;
++ /* alive scsi_device under port of interest */
++ goto unlock_host_lock;
++ }
++
++ /* port is about to be removed, so no more unit_add or slave_alloc */
++ zfcp_sysfs_port_set_removing(port);
++ in_use = false;
++
++unlock_host_lock:
++ spin_unlock_irqrestore(adapter->scsi_host->host_lock, flags);
++unlock_port_units_mutex:
++ mutex_unlock(&zfcp_sysfs_port_units_mutex);
++ return in_use;
++}
++
+ static ssize_t zfcp_sysfs_port_remove_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+@@ -259,16 +306,11 @@ static ssize_t zfcp_sysfs_port_remove_st
+ else
+ retval = 0;
+
+- mutex_lock(&zfcp_sysfs_port_units_mutex);
+- if (atomic_read(&port->units) > 0) {
++ if (zfcp_sysfs_port_in_use(port)) {
+ retval = -EBUSY;
+- mutex_unlock(&zfcp_sysfs_port_units_mutex);
+ put_device(&port->dev); /* undo zfcp_get_port_by_wwpn() */
+ goto out;
+ }
+- /* port is about to be removed, so no more unit_add */
+- atomic_set(&port->units, -1);
+- mutex_unlock(&zfcp_sysfs_port_units_mutex);
+
+ write_lock_irq(&adapter->port_list_lock);
+ list_del(&port->list);
+--- a/drivers/s390/scsi/zfcp_unit.c
++++ b/drivers/s390/scsi/zfcp_unit.c
+@@ -123,7 +123,7 @@ int zfcp_unit_add(struct zfcp_port *port
+ int retval = 0;
+
+ mutex_lock(&zfcp_sysfs_port_units_mutex);
+- if (atomic_read(&port->units) == -1) {
++ if (zfcp_sysfs_port_is_removing(port)) {
+ /* port is already gone */
+ retval = -ENODEV;
+ goto out;
+@@ -167,8 +167,14 @@ int zfcp_unit_add(struct zfcp_port *port
+ write_lock_irq(&port->unit_list_lock);
+ list_add_tail(&unit->list, &port->unit_list);
+ write_unlock_irq(&port->unit_list_lock);
++ /*
++ * lock order: shost->scan_mutex before zfcp_sysfs_port_units_mutex
++ * due to zfcp_unit_scsi_scan() => zfcp_scsi_slave_alloc()
++ */
++ mutex_unlock(&zfcp_sysfs_port_units_mutex);
+
+ zfcp_unit_scsi_scan(unit);
++ return retval;
+
+ out:
+ mutex_unlock(&zfcp_sysfs_port_units_mutex);
diff --git a/series.conf b/series.conf
index bc20e7d29b..3b3cc710e7 100644
--- a/series.conf
+++ b/series.conf
@@ -22561,6 +22561,7 @@
patches.suse/memcg-make-it-work-on-sparse-non-0-node-systems.patch
patches.suse/kernel-signal.c-trace_signal_deliver-when-signal_gro.patch
patches.fixes/scsi-zfcp-fix-missing-zfcp_port-reference-put-on-ebusy-from-port_remove
+ patches.fixes/scsi-zfcp-fix-to-prevent-port_remove-with-pure-auto-scan-luns-only-sdevs
patches.drivers/leds-avoid-flush_work-in-atomic-context.patch
patches.drivers/i2c-dev-fix-potential-memory-leak-in-i2cdev_ioctl_rd.patch
patches.arch/KVM-PPC-Book3S-HV-XIVE-Do-not-clear-IRQ-data-of-pass.patch