diff options
author | Steffen Maier <maier@linux.ibm.com> | 2022-07-29 19:25:29 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-21 16:16:13 +0300 |
commit | b8aad5eba7385fa7f386624d2a0ef5f24225980a (patch) | |
tree | 8d8f7ea9f7f264dfe0b66d061e8822548170f80d /drivers | |
parent | 5e0da18956d38e7106664dc1d06367b22f06edd3 (diff) | |
download | linux-b8aad5eba7385fa7f386624d2a0ef5f24225980a.tar.xz |
scsi: zfcp: Fix missing auto port scan and thus missing target ports
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>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/s390/scsi/zfcp_fc.c | 29 | ||||
-rw-r--r-- | drivers/s390/scsi/zfcp_fc.h | 6 | ||||
-rw-r--r-- | drivers/s390/scsi/zfcp_fsf.c | 4 |
3 files changed, 26 insertions, 13 deletions
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c index 511bf8e0a436..b61acbb09be3 100644 --- a/drivers/s390/scsi/zfcp_fc.c +++ b/drivers/s390/scsi/zfcp_fc.c @@ -145,27 +145,33 @@ void zfcp_fc_enqueue_event(struct zfcp_adapter *adapter, 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) @@ -181,9 +187,12 @@ static void zfcp_fc_wka_port_offline(struct work_struct *work) 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); } @@ -193,13 +202,15 @@ static void zfcp_fc_wka_port_put(struct zfcp_fc_wka_port *wka_port) 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; diff --git a/drivers/s390/scsi/zfcp_fc.h b/drivers/s390/scsi/zfcp_fc.h index 6902ae1f8e4f..25bebfaa8cbc 100644 --- a/drivers/s390/scsi/zfcp_fc.h +++ b/drivers/s390/scsi/zfcp_fc.h @@ -185,7 +185,8 @@ 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 @@ -195,7 +196,8 @@ 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; diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c index 37d450f46952..8401c42db541 100644 --- a/drivers/s390/scsi/zfcp_fsf.c +++ b/drivers/s390/scsi/zfcp_fsf.c @@ -1889,7 +1889,7 @@ static void zfcp_fsf_open_wka_port_handler(struct zfcp_fsf_req *req) wka_port->status = ZFCP_FC_WKA_PORT_ONLINE; } out: - wake_up(&wka_port->completion_wq); + wake_up(&wka_port->opened); } /** @@ -1948,7 +1948,7 @@ static void zfcp_fsf_close_wka_port_handler(struct zfcp_fsf_req *req) } wka_port->status = ZFCP_FC_WKA_PORT_OFFLINE; - wake_up(&wka_port->completion_wq); + wake_up(&wka_port->closed); } /** |