--- /dev/null
+From 4da8c5f76825269f28d6a89fa752934a4bcb6dfa Mon Sep 17 00:00:00 2001
+From: Steffen Maier <maier@linux.ibm.com>
+Date: Fri, 29 Jul 2022 18:25:29 +0200
+Subject: scsi: zfcp: Fix missing auto port scan and thus missing target ports
+
+From: Steffen Maier <maier@linux.ibm.com>
+
+commit 4da8c5f76825269f28d6a89fa752934a4bcb6dfa upstream.
+
+Case (1):
+ The only waiter on wka_port->completion_wq is zfcp_fc_wka_port_get()
+ trying to open a WKA port. As such it should only be woken up by WKA port
+ *open* responses, not by WKA port close responses.
+
+Case (2):
+ A close WKA port response coming in just after having sent a new open WKA
+ port request and before blocking for the open response with wait_event()
+ in zfcp_fc_wka_port_get() erroneously renders the wait_event a NOP
+ because the close handler overwrites wka_port->status. Hence the
+ wait_event condition is erroneously true and it does not enter blocking
+ state.
+
+With non-negligible probability, the following time space sequence happens
+depending on timing without this fix:
+
+user process ERP thread zfcp work queue tasklet system work queue
+============ ========== =============== ======= =================
+$ echo 1 > online
+zfcp_ccw_set_online
+zfcp_ccw_activate
+zfcp_erp_adapter_reopen
+msleep scan backoff zfcp_erp_strategy
+| ...
+| zfcp_erp_action_cleanup
+| ...
+| queue delayed scan_work
+| queue ns_up_work
+| ns_up_work:
+| zfcp_fc_wka_port_get
+| open wka request
+| open response
+| GSPN FC-GS
+| RSPN FC-GS [NPIV-only]
+| zfcp_fc_wka_port_put
+| (--wka->refcount==0)
+| sched delayed wka->work
+|
+~~~Case (1)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+zfcp_erp_wait
+flush scan_work
+| wka->work:
+| wka->status=CLOSING
+| close wka request
+| scan_work:
+| zfcp_fc_wka_port_get
+| (wka->status==CLOSING)
+| wka->status=OPENING
+| open wka request
+| wait_event
+| | close response
+| | wka->status=OFFLINE
+| | wake_up /*WRONG*/
+~~~Case (2)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+| wka->work:
+| wka->status=CLOSING
+| close wka request
+zfcp_erp_wait
+flush scan_work
+| scan_work:
+| zfcp_fc_wka_port_get
+| (wka->status==CLOSING)
+| wka->status=OPENING
+| open wka request
+| close response
+| wka->status=OFFLINE
+| wake_up /*WRONG&NOP*/
+| wait_event /*NOP*/
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+| (wka->status!=ONLINE)
+| return -EIO
+| return early
+ open response
+ wka->status=ONLINE
+ wake_up /*NOP*/
+
+So we erroneously end up with no automatic port scan. This is a big problem
+when it happens during boot. The timing is influenced by v3.19 commit
+18f87a67e6d6 ("zfcp: auto port scan resiliency").
+
+Fix it by fully mutually excluding zfcp_fc_wka_port_get() and
+zfcp_fc_wka_port_offline(). For that to work, we make the latter block
+until we got the response for a close WKA port. In order not to penalize
+the system workqueue, we move wka_port->work to our own adapter workqueue.
+Note that before v2.6.30 commit 828bc1212a68 ("[SCSI] zfcp: Set WKA-port to
+offline on adapter deactivation"), zfcp did block in
+zfcp_fc_wka_port_offline() as well, but with a different condition.
+
+While at it, make non-functional cleanups to improve code reading in
+zfcp_fc_wka_port_get(). If we cannot send the WKA port open request, don't
+rely on the subsequent wait_event condition to immediately let this case
+pass without blocking. Also don't want to rely on the additional condition
+handling the refcount to be skipped just to finally return with -EIO.
+
+Link: https://lore.kernel.org/r/20220729162529.1620730-1-maier@linux.ibm.com
+Fixes: 5ab944f97e09 ("[SCSI] zfcp: attach and release SAN nameserver port on demand")
+Cc: <stable@vger.kernel.org> #v2.6.28+
+Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
+Signed-off-by: Steffen Maier <maier@linux.ibm.com>
+Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/s390/scsi/zfcp_fc.c | 29 ++++++++++++++++++++---------
+ drivers/s390/scsi/zfcp_fc.h | 6 ++++--
+ drivers/s390/scsi/zfcp_fsf.c | 4 ++--
+ 3 files changed, 26 insertions(+), 13 deletions(-)
+
+--- a/drivers/s390/scsi/zfcp_fc.c
++++ b/drivers/s390/scsi/zfcp_fc.c
+@@ -146,27 +146,33 @@ void zfcp_fc_enqueue_event(struct zfcp_a
+
+ static int zfcp_fc_wka_port_get(struct zfcp_fc_wka_port *wka_port)
+ {
++ int ret = -EIO;
++
+ if (mutex_lock_interruptible(&wka_port->mutex))
+ return -ERESTARTSYS;
+
+ if (wka_port->status == ZFCP_FC_WKA_PORT_OFFLINE ||
+ wka_port->status == ZFCP_FC_WKA_PORT_CLOSING) {
+ wka_port->status = ZFCP_FC_WKA_PORT_OPENING;
+- if (zfcp_fsf_open_wka_port(wka_port))
++ if (zfcp_fsf_open_wka_port(wka_port)) {
++ /* could not even send request, nothing to wait for */
+ wka_port->status = ZFCP_FC_WKA_PORT_OFFLINE;
++ goto out;
++ }
+ }
+
+- mutex_unlock(&wka_port->mutex);
+-
+- wait_event(wka_port->completion_wq,
++ wait_event(wka_port->opened,
+ wka_port->status == ZFCP_FC_WKA_PORT_ONLINE ||
+ wka_port->status == ZFCP_FC_WKA_PORT_OFFLINE);
+
+ if (wka_port->status == ZFCP_FC_WKA_PORT_ONLINE) {
+ atomic_inc(&wka_port->refcount);
+- return 0;
++ ret = 0;
++ goto out;
+ }
+- return -EIO;
++out:
++ mutex_unlock(&wka_port->mutex);
++ return ret;
+ }
+
+ static void zfcp_fc_wka_port_offline(struct work_struct *work)
+@@ -182,9 +188,12 @@ static void zfcp_fc_wka_port_offline(str
+
+ wka_port->status = ZFCP_FC_WKA_PORT_CLOSING;
+ if (zfcp_fsf_close_wka_port(wka_port)) {
++ /* could not even send request, nothing to wait for */
+ wka_port->status = ZFCP_FC_WKA_PORT_OFFLINE;
+- wake_up(&wka_port->completion_wq);
++ goto out;
+ }
++ wait_event(wka_port->closed,
++ wka_port->status == ZFCP_FC_WKA_PORT_OFFLINE);
+ out:
+ mutex_unlock(&wka_port->mutex);
+ }
+@@ -194,13 +203,15 @@ static void zfcp_fc_wka_port_put(struct
+ if (atomic_dec_return(&wka_port->refcount) != 0)
+ return;
+ /* wait 10 milliseconds, other reqs might pop in */
+- schedule_delayed_work(&wka_port->work, HZ / 100);
++ queue_delayed_work(wka_port->adapter->work_queue, &wka_port->work,
++ msecs_to_jiffies(10));
+ }
+
+ static void zfcp_fc_wka_port_init(struct zfcp_fc_wka_port *wka_port, u32 d_id,
+ struct zfcp_adapter *adapter)
+ {
+- init_waitqueue_head(&wka_port->completion_wq);
++ init_waitqueue_head(&wka_port->opened);
++ init_waitqueue_head(&wka_port->closed);
+
+ wka_port->adapter = adapter;
+ wka_port->d_id = d_id;
+--- a/drivers/s390/scsi/zfcp_fc.h
++++ b/drivers/s390/scsi/zfcp_fc.h
+@@ -170,7 +170,8 @@ enum zfcp_fc_wka_status {
+ /**
+ * struct zfcp_fc_wka_port - representation of well-known-address (WKA) FC port
+ * @adapter: Pointer to adapter structure this WKA port belongs to
+- * @completion_wq: Wait for completion of open/close command
++ * @opened: Wait for completion of open command
++ * @closed: Wait for completion of close command
+ * @status: Current status of WKA port
+ * @refcount: Reference count to keep port open as long as it is in use
+ * @d_id: FC destination id or well-known-address
+@@ -180,7 +181,8 @@ enum zfcp_fc_wka_status {
+ */
+ struct zfcp_fc_wka_port {
+ struct zfcp_adapter *adapter;
+- wait_queue_head_t completion_wq;
++ wait_queue_head_t opened;
++ wait_queue_head_t closed;
+ enum zfcp_fc_wka_status status;
+ atomic_t refcount;
+ u32 d_id;
+--- a/drivers/s390/scsi/zfcp_fsf.c
++++ b/drivers/s390/scsi/zfcp_fsf.c
+@@ -1582,7 +1582,7 @@ static void zfcp_fsf_open_wka_port_handl
+ wka_port->status = ZFCP_FC_WKA_PORT_ONLINE;
+ }
+ out:
+- wake_up(&wka_port->completion_wq);
++ wake_up(&wka_port->opened);
+ }
+
+ /**
+@@ -1640,7 +1640,7 @@ static void zfcp_fsf_close_wka_port_hand
+ }
+
+ wka_port->status = ZFCP_FC_WKA_PORT_OFFLINE;
+- wake_up(&wka_port->completion_wq);
++ wake_up(&wka_port->closed);
+ }
+
+ /**
projects / thirdparty / kernel / stable-queue.git / commitdiff
