linux-stable.git/drivers/s390, branch v4.9.331

s390/dasd: fix Oops in dasd_alias_get_start_dev due to missing pavgroup

2022-09-28T08:55:46+00:00

commit db7ba07108a48c0f95b74fabbfd5d63e924f992d upstream.

Fix Oops in dasd_alias_get_start_dev() function caused by the pavgroup
pointer being NULL.

The pavgroup pointer is checked on the entrance of the function but
without the lcu->lock being held. Therefore there is a race window
between dasd_alias_get_start_dev() and _lcu_update() which sets
pavgroup to NULL with the lcu->lock held.

Fix by checking the pavgroup pointer with lcu->lock held.

Cc:  # 2.6.25+
Fixes: 8e09f21574ea ("[S390] dasd: add hyper PAV support to DASD device driver, part 1")
Signed-off-by: Stefan Haberland 
Reviewed-by: Jan Hoeppner 
Link: https://lore.kernel.org/r/20220919154931.4123002-2-sth@linux.ibm.com
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

scsi: zfcp: Fix missing auto port scan and thus missing target ports

2022-08-25T09:09:25+00:00

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:  #v2.6.28+
Reviewed-by: Benjamin Block 
Signed-off-by: Steffen Maier 
Signed-off-by: Martin K. Petersen 
Signed-off-by: Greg Kroah-Hartman

tty: the rest, stop using tty_schedule_flip()

2022-07-29T15:05:47+00:00

commit b68b914494df4f79b4e9b58953110574af1cb7a2 upstream.

Since commit a9c3f68f3cd8d (tty: Fix low_latency BUG) in 2014,
tty_flip_buffer_push() is only a wrapper to tty_schedule_flip(). We are
going to remove the latter (as it is used less), so call the former in
the rest of the users.

Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: William Hubbs 
Cc: Chris Brannon 
Cc: Kirk Reiser 
Cc: Samuel Thibault 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: Alexander Gordeev 
Reviewed-by: Johan Hovold 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20211122111648.30379-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

s390/lcs: fix variable dereferenced before check

2022-05-18T07:15:43+00:00

[ Upstream commit 671bb35c8e746439f0ed70815968f9a4f20a8deb ]

smatch complains about
drivers/s390/net/lcs.c:1741 lcs_get_control() warn: variable dereferenced before check 'card->dev' (see line 1739)

Fixes: 27eb5ac8f015 ("[PATCH] s390: lcs driver bug fixes and improvements [1/2]")
Signed-off-by: Alexandra Winter 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

s390/ctcm: fix potential memory leak

2022-05-18T07:15:43+00:00

[ Upstream commit 0c0b20587b9f25a2ad14db7f80ebe49bdf29920a ]

smatch complains about
drivers/s390/net/ctcm_mpc.c:1210 ctcmpc_unpack_skb() warn: possible memory leak of 'mpcginfo'

mpc_action_discontact() did not free mpcginfo. Consolidate the freeing in
ctcmpc_unpack_skb().

Fixes: 293d984f0e36 ("ctcm: infrastructure for replaced ctc driver")
Signed-off-by: Alexandra Winter 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

s390/ctcm: fix variable dereferenced before check

2022-05-18T07:15:43+00:00

[ Upstream commit 2c50c6867c85afee6f2b3bcbc50fc9d0083d1343 ]

Found by cppcheck and smatch.
smatch complains about
drivers/s390/net/ctcm_sysfs.c:43 ctcm_buffer_write() warn: variable dereferenced before check 'priv' (see line 42)

Fixes: 3c09e2647b5e ("ctcm: rename READ/WRITE defines to avoid redefinitions")
Reported-by: Colin Ian King 
Signed-off-by: Alexandra Winter 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

scsi: zfcp: Fix failed recovery on gone remote port with non-NPIV FCP devices

2022-02-08T17:15:26+00:00

commit 8c9db6679be4348b8aae108e11d4be2f83976e30 upstream.

Suppose we have an environment with a number of non-NPIV FCP devices
(virtual HBAs / FCP devices / zfcp "adapter"s) sharing the same physical
FCP channel (HBA port) and its I_T nexus. Plus a number of storage target
ports zoned to such shared channel. Now one target port logs out of the
fabric causing an RSCN. Zfcp reacts with an ADISC ELS and subsequent port
recovery depending on the ADISC result. This happens on all such FCP
devices (in different Linux images) concurrently as they all receive a copy
of this RSCN. In the following we look at one of those FCP devices.

Requests other than FSF_QTCB_FCP_CMND can be slow until they get a
response.

Depending on which requests are affected by slow responses, there are
different recovery outcomes. Here we want to fix failed recoveries on port
or adapter level by avoiding recovery requests that can be slow.

We need the cached N_Port_ID for the remote port "link" test with ADISC.
Just before sending the ADISC, we now intentionally forget the old cached
N_Port_ID. The idea is that on receiving an RSCN for a port, we have to
assume that any cached information about this port is stale.  This forces a
fresh new GID_PN [FC-GS] nameserver lookup on any subsequent recovery for
the same port. Since we typically can still communicate with the nameserver
efficiently, we now reach steady state quicker: Either the nameserver still
does not know about the port so we stop recovery, or the nameserver already
knows the port potentially with a new N_Port_ID and we can successfully and
quickly perform open port recovery.  For the one case, where ADISC returns
successfully, we re-initialize port->d_id because that case does not
involve any port recovery.

This also solves a problem if the storage WWPN quickly logs into the fabric
again but with a different N_Port_ID. Such as on virtual WWPN takeover
during target NPIV failover.
[https://www.redbooks.ibm.com/abstracts/redp5477.html] In that case the
RSCN from the storage FDISC was ignored by zfcp and we could not
successfully recover the failover. On some later failback on the storage,
we could have been lucky if the virtual WWPN got the same old N_Port_ID
from the SAN switch as we still had cached.  Then the related RSCN
triggered a successful port reopen recovery.  However, there is no
guarantee to get the same N_Port_ID on NPIV FDISC.

Even though NPIV-enabled FCP devices are not affected by this problem, this
code change optimizes recovery time for gone remote ports as a side effect.
The timely drop of cached N_Port_IDs prevents unnecessary slow open port
attempts.

While the problem might have been in code before v2.6.32 commit
799b76d09aee ("[SCSI] zfcp: Decouple gid_pn requests from erp") this fix
depends on the gid_pn_work introduced with that commit, so we mark it as
culprit to satisfy fix dependencies.

Note: Point-to-point remote port is already handled separately and gets its
N_Port_ID from the cached peer_d_id. So resetting port->d_id in general
does not affect PtP.

Link: https://lore.kernel.org/r/20220118165803.3667947-1-maier@linux.ibm.com
Fixes: 799b76d09aee ("[SCSI] zfcp: Decouple gid_pn requests from erp")
Cc:  #2.6.32+
Suggested-by: Benjamin Block 
Reviewed-by: Benjamin Block 
Signed-off-by: Steffen Maier 
Signed-off-by: Martin K. Petersen 
Signed-off-by: Greg Kroah-Hartman

s390/sclp_vt220: fix console name to match device

2021-07-20T14:21:11+00:00

[ Upstream commit b7d91d230a119fdcc334d10c9889ce9c5e15118b ]

Console name reported in /proc/consoles:

  ttyS1                -W- (EC p  )    4:65

does not match the char device name:

  crw--w----    1 root     root        4,  65 May 17 12:18 /dev/ttysclp0

so debian-installer inside a QEMU s390x instance gets confused and fails
to start with the following error:

  steal-ctty: No such file or directory

Signed-off-by: Valentin Vidic 
Link: https://lore.kernel.org/r/20210427194010.9330-1-vvidic@valentin-vidic.from.hr
Signed-off-by: Christian Borntraeger 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Sasha Levin

s390/cio: dont call css_wait_for_slow_path() inside a lock

2021-07-20T14:20:57+00:00

commit c749d8c018daf5fba6dfac7b6c5c78b27efd7d65 upstream.

Currently css_wait_for_slow_path() gets called inside the chp->lock.
The path-verification-loop of slowpath inside this lock could lead to
deadlock as reported by the lockdep validator.

The ccw_device_get_chp_desc() during the instance of a device-set-online
would try to acquire the same 'chp->lock' to read the chp->desc.
The instance of this function can get called from multiple scenario,
like probing or setting-device online manually. This could, in some
corner-cases lead to the deadlock.

lockdep validator reported this as,

        CPU0                    CPU1
        ----                    ----
   lock(&chp->lock);
                                lock(kn->active#43);
                                lock(&chp->lock);
   lock((wq_completion)cio);

The chp->lock was introduced to serialize the access of struct
channel_path. This lock is not needed for the css_wait_for_slow_path()
function, so invoke the slow-path function outside this lock.

Fixes: b730f3a93395 ("[S390] cio: add lock to struct channel_path")
Cc: 
Reviewed-by: Peter Oberparleiter 
Signed-off-by: Vineeth Vijayan 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Greg Kroah-Hartman

s390/dasd: fix hanging DASD driver unbind

2021-03-17T15:10:15+00:00

commit 7d365bd0bff3c0310c39ebaffc9a8458e036d666 upstream.

In case of an unbind of the DASD device driver the function
dasd_generic_remove() is called which shuts down the device.
Among others this functions removes the int_handler from the cdev.
During shutdown the device cancels all outstanding IO requests and waits
for completion of the clear request.
Unfortunately the clear interrupt will never be received when there is no
interrupt handler connected.

Fix by moving the int_handler removal after the call to the state machine
where no request or interrupt is outstanding.

Cc: stable@vger.kernel.org
Signed-off-by: Stefan Haberland 
Tested-by: Bjoern Walk 
Reviewed-by: Jan Hoeppner 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman