<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/scsi, branch v4.20.4</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>scsi: sd: Fix cache_type_store()</title>
<updated>2019-01-22T20:09:51+00:00</updated>
<author>
<name>Ivan Mironov</name>
<email>mironov.ivan@gmail.com</email>
</author>
<published>2018-12-23T07:41:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=871858ab00355ddc02dd930804d02b2927f43288'/>
<id>871858ab00355ddc02dd930804d02b2927f43288</id>
<content type='text'>
commit 44759979a49bfd2d20d789add7fa81a21eb1a4ab upstream.

Changing of caching mode via /sys/devices/.../scsi_disk/.../cache_type may
fail if device responds to MODE SENSE command with DPOFUA flag set, and
then checks this flag to be not set on MODE SELECT command.

In this scenario, when trying to change cache_type, write always fails:

	# echo "none" &gt;cache_type
	bash: echo: write error: Invalid argument

And following appears in dmesg:

	[13007.865745] sd 1:0:1:0: [sda] Sense Key : Illegal Request [current]
	[13007.865753] sd 1:0:1:0: [sda] Add. Sense: Invalid field in parameter list

From SBC-4 r15, 6.5.1 "Mode pages overview", description of DEVICE-SPECIFIC
PARAMETER field in the mode parameter header:
	...
	The write protect (WP) bit for mode data sent with a MODE SELECT
	command shall be ignored by the device server.
	...
	The DPOFUA bit is reserved for mode data sent with a MODE SELECT
	command.
	...

The remaining bits in the DEVICE-SPECIFIC PARAMETER byte are also reserved
and shall be set to zero.

[mkp: shuffled commentary to commit description]

Cc: stable@vger.kernel.org
Signed-off-by: Ivan Mironov &lt;mironov.ivan@gmail.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 44759979a49bfd2d20d789add7fa81a21eb1a4ab upstream.

Changing of caching mode via /sys/devices/.../scsi_disk/.../cache_type may
fail if device responds to MODE SENSE command with DPOFUA flag set, and
then checks this flag to be not set on MODE SELECT command.

In this scenario, when trying to change cache_type, write always fails:

	# echo "none" &gt;cache_type
	bash: echo: write error: Invalid argument

And following appears in dmesg:

	[13007.865745] sd 1:0:1:0: [sda] Sense Key : Illegal Request [current]
	[13007.865753] sd 1:0:1:0: [sda] Add. Sense: Invalid field in parameter list

From SBC-4 r15, 6.5.1 "Mode pages overview", description of DEVICE-SPECIFIC
PARAMETER field in the mode parameter header:
	...
	The write protect (WP) bit for mode data sent with a MODE SELECT
	command shall be ignored by the device server.
	...
	The DPOFUA bit is reserved for mode data sent with a MODE SELECT
	command.
	...

The remaining bits in the DEVICE-SPECIFIC PARAMETER byte are also reserved
and shall be set to zero.

[mkp: shuffled commentary to commit description]

Cc: stable@vger.kernel.org
Signed-off-by: Ivan Mironov &lt;mironov.ivan@gmail.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>scsi: core: Synchronize request queue PM status only on successful resume</title>
<updated>2019-01-22T20:09:51+00:00</updated>
<author>
<name>Stanley Chu</name>
<email>stanley.chu@mediatek.com</email>
</author>
<published>2019-01-03T14:08:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ee16d72948516c08087ea12a151e150ea4324edb'/>
<id>ee16d72948516c08087ea12a151e150ea4324edb</id>
<content type='text'>
commit 3f7e62bba0003f9c68f599f5997c4647ef5b4f4e upstream.

The commit 356fd2663cff ("scsi: Set request queue runtime PM status back to
active on resume") fixed up the inconsistent RPM status between request
queue and device. However changing request queue RPM status shall be done
only on successful resume, otherwise status may be still inconsistent as
below,

Request queue: RPM_ACTIVE
Device: RPM_SUSPENDED

This ends up soft lockup because requests can be submitted to underlying
devices but those devices and their required resource are not resumed.

For example,

After above inconsistent status happens, IO request can be submitted to UFS
device driver but required resource (like clock) is not resumed yet thus
lead to warning as below call stack,

WARN_ON(hba-&gt;clk_gating.state != CLKS_ON);
ufshcd_queuecommand
scsi_dispatch_cmd
scsi_request_fn
__blk_run_queue
cfq_insert_request
__elv_add_request
blk_flush_plug_list
blk_finish_plug
jbd2_journal_commit_transaction
kjournald2

We may see all behind IO requests hang because of no response from storage
host or device and then soft lockup happens in system. In the end, system
may crash in many ways.

Fixes: 356fd2663cff (scsi: Set request queue runtime PM status back to active on resume)
Cc: stable@vger.kernel.org
Signed-off-by: Stanley Chu &lt;stanley.chu@mediatek.com&gt;
Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 3f7e62bba0003f9c68f599f5997c4647ef5b4f4e upstream.

The commit 356fd2663cff ("scsi: Set request queue runtime PM status back to
active on resume") fixed up the inconsistent RPM status between request
queue and device. However changing request queue RPM status shall be done
only on successful resume, otherwise status may be still inconsistent as
below,

Request queue: RPM_ACTIVE
Device: RPM_SUSPENDED

This ends up soft lockup because requests can be submitted to underlying
devices but those devices and their required resource are not resumed.

For example,

After above inconsistent status happens, IO request can be submitted to UFS
device driver but required resource (like clock) is not resumed yet thus
lead to warning as below call stack,

WARN_ON(hba-&gt;clk_gating.state != CLKS_ON);
ufshcd_queuecommand
scsi_dispatch_cmd
scsi_request_fn
__blk_run_queue
cfq_insert_request
__elv_add_request
blk_flush_plug_list
blk_finish_plug
jbd2_journal_commit_transaction
kjournald2

We may see all behind IO requests hang because of no response from storage
host or device and then soft lockup happens in system. In the end, system
may crash in many ways.

Fixes: 356fd2663cff (scsi: Set request queue runtime PM status back to active on resume)
Cc: stable@vger.kernel.org
Signed-off-by: Stanley Chu &lt;stanley.chu@mediatek.com&gt;
Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>scsi: lpfc: do not set queue-&gt;page_count to 0 if pc_sli4_params.wqpcnt is invalid</title>
<updated>2019-01-13T08:24:01+00:00</updated>
<author>
<name>Ewan D. Milne</name>
<email>emilne@redhat.com</email>
</author>
<published>2018-12-13T20:25:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a88b5ff6cff9514bd8297ae4c4815c0410621bbb'/>
<id>a88b5ff6cff9514bd8297ae4c4815c0410621bbb</id>
<content type='text'>
commit 4e87eb2f46ea547d12a276b2e696ab934d16cfb6 upstream.

Certain older adapters such as the OneConnect OCe10100 may not have a valid
wqpcnt value.  In this case, do not set queue-&gt;page_count to 0 in
lpfc_sli4_queue_alloc() as this will prevent the driver from initializing.

Fixes: 895427bd01 ("scsi: lpfc: NVME Initiator: Base modifications")
Cc: stable@vger.kernel.org # 4.11+
Signed-off-by: Ewan D. Milne &lt;emilne@redhat.com&gt;
Reviewed-by: Laurence Oberman &lt;loberman@redhat.com&gt;
Tested-by:   Laurence Oberman &lt;loberman@redhat.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 4e87eb2f46ea547d12a276b2e696ab934d16cfb6 upstream.

Certain older adapters such as the OneConnect OCe10100 may not have a valid
wqpcnt value.  In this case, do not set queue-&gt;page_count to 0 in
lpfc_sli4_queue_alloc() as this will prevent the driver from initializing.

Fixes: 895427bd01 ("scsi: lpfc: NVME Initiator: Base modifications")
Cc: stable@vger.kernel.org # 4.11+
Signed-off-by: Ewan D. Milne &lt;emilne@redhat.com&gt;
Reviewed-by: Laurence Oberman &lt;loberman@redhat.com&gt;
Tested-by:   Laurence Oberman &lt;loberman@redhat.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi</title>
<updated>2018-12-22T23:03:00+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-12-22T23:03:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9105b8aa50c182371533fc97db64fc8f26f051b3'/>
<id>9105b8aa50c182371533fc97db64fc8f26f051b3</id>
<content type='text'>
Pull SCSI fixes from James Bottomley:
 "This is two simple target fixes and one discard related I/O starvation
  problem in sd.

  The discard problem occurs because the discard page doesn't have a
  mempool backing so if the allocation fails due to memory pressure, we
  then lose the forward progress we require if the writeout is on the
  same device. The fix is to back it with a mempool"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: sd: use mempool for discard special page
  scsi: target: iscsi: cxgbit: add missing spin_lock_init()
  scsi: target: iscsi: cxgbit: fix csk leak
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull SCSI fixes from James Bottomley:
 "This is two simple target fixes and one discard related I/O starvation
  problem in sd.

  The discard problem occurs because the discard page doesn't have a
  mempool backing so if the allocation fails due to memory pressure, we
  then lose the forward progress we require if the writeout is on the
  same device. The fix is to back it with a mempool"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: sd: use mempool for discard special page
  scsi: target: iscsi: cxgbit: add missing spin_lock_init()
  scsi: target: iscsi: cxgbit: fix csk leak
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi</title>
<updated>2018-12-18T17:38:34+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-12-18T17:38:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ddfbab46539f2d37a9e9d357b054486b51f7dc27'/>
<id>ddfbab46539f2d37a9e9d357b054486b51f7dc27</id>
<content type='text'>
Pull SCSI fixes from James Bottomley:
 "Three fixes: The t10-pi one is a regression from the 4.19 release, the
  qla2xxx one is a 4.20 merge window regression and the bnx2fc is a very
  old bug"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: t10-pi: Return correct ref tag when queue has no integrity profile
  scsi: bnx2fc: Fix NULL dereference in error handling
  Revert "scsi: qla2xxx: Fix NVMe Target discovery"
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull SCSI fixes from James Bottomley:
 "Three fixes: The t10-pi one is a regression from the 4.19 release, the
  qla2xxx one is a 4.20 merge window regression and the bnx2fc is a very
  old bug"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: t10-pi: Return correct ref tag when queue has no integrity profile
  scsi: bnx2fc: Fix NULL dereference in error handling
  Revert "scsi: qla2xxx: Fix NVMe Target discovery"
</pre>
</div>
</content>
</entry>
<entry>
<title>scsi: sd: use mempool for discard special page</title>
<updated>2018-12-13T01:11:54+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2018-12-12T13:46:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=61cce6f6eeced5ddd9cac55e807fe28b4f18c1ba'/>
<id>61cce6f6eeced5ddd9cac55e807fe28b4f18c1ba</id>
<content type='text'>
When boxes are run near (or to) OOM, we have a problem with the discard
page allocation in sd. If we fail allocating the special page, we return
busy, and it'll get retried. But since ordering is honored for dispatch
requests, we can keep retrying this same IO and failing. Behind that IO
could be requests that want to free memory, but they never get the
chance. This means you get repeated spews of traces like this:

[1201401.625972] Call Trace:
[1201401.631748]  dump_stack+0x4d/0x65
[1201401.639445]  warn_alloc+0xec/0x190
[1201401.647335]  __alloc_pages_slowpath+0xe84/0xf30
[1201401.657722]  ? get_page_from_freelist+0x11b/0xb10
[1201401.668475]  ? __alloc_pages_slowpath+0x2e/0xf30
[1201401.679054]  __alloc_pages_nodemask+0x1f9/0x210
[1201401.689424]  alloc_pages_current+0x8c/0x110
[1201401.699025]  sd_setup_write_same16_cmnd+0x51/0x150
[1201401.709987]  sd_init_command+0x49c/0xb70
[1201401.719029]  scsi_setup_cmnd+0x9c/0x160
[1201401.727877]  scsi_queue_rq+0x4d9/0x610
[1201401.736535]  blk_mq_dispatch_rq_list+0x19a/0x360
[1201401.747113]  blk_mq_sched_dispatch_requests+0xff/0x190
[1201401.758844]  __blk_mq_run_hw_queue+0x95/0xa0
[1201401.768653]  blk_mq_run_work_fn+0x2c/0x30
[1201401.777886]  process_one_work+0x14b/0x400
[1201401.787119]  worker_thread+0x4b/0x470
[1201401.795586]  kthread+0x110/0x150
[1201401.803089]  ? rescuer_thread+0x320/0x320
[1201401.812322]  ? kthread_park+0x90/0x90
[1201401.820787]  ? do_syscall_64+0x53/0x150
[1201401.829635]  ret_from_fork+0x29/0x40

Ensure that the discard page allocation has a mempool backing, so we
know we can make progress.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When boxes are run near (or to) OOM, we have a problem with the discard
page allocation in sd. If we fail allocating the special page, we return
busy, and it'll get retried. But since ordering is honored for dispatch
requests, we can keep retrying this same IO and failing. Behind that IO
could be requests that want to free memory, but they never get the
chance. This means you get repeated spews of traces like this:

[1201401.625972] Call Trace:
[1201401.631748]  dump_stack+0x4d/0x65
[1201401.639445]  warn_alloc+0xec/0x190
[1201401.647335]  __alloc_pages_slowpath+0xe84/0xf30
[1201401.657722]  ? get_page_from_freelist+0x11b/0xb10
[1201401.668475]  ? __alloc_pages_slowpath+0x2e/0xf30
[1201401.679054]  __alloc_pages_nodemask+0x1f9/0x210
[1201401.689424]  alloc_pages_current+0x8c/0x110
[1201401.699025]  sd_setup_write_same16_cmnd+0x51/0x150
[1201401.709987]  sd_init_command+0x49c/0xb70
[1201401.719029]  scsi_setup_cmnd+0x9c/0x160
[1201401.727877]  scsi_queue_rq+0x4d9/0x610
[1201401.736535]  blk_mq_dispatch_rq_list+0x19a/0x360
[1201401.747113]  blk_mq_sched_dispatch_requests+0xff/0x190
[1201401.758844]  __blk_mq_run_hw_queue+0x95/0xa0
[1201401.768653]  blk_mq_run_work_fn+0x2c/0x30
[1201401.777886]  process_one_work+0x14b/0x400
[1201401.787119]  worker_thread+0x4b/0x470
[1201401.795586]  kthread+0x110/0x150
[1201401.803089]  ? rescuer_thread+0x320/0x320
[1201401.812322]  ? kthread_park+0x90/0x90
[1201401.820787]  ? do_syscall_64+0x53/0x150
[1201401.829635]  ret_from_fork+0x29/0x40

Ensure that the discard page allocation has a mempool backing, so we
know we can make progress.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>scsi: bnx2fc: Fix NULL dereference in error handling</title>
<updated>2018-12-08T03:23:41+00:00</updated>
<author>
<name>Dan Carpenter</name>
<email>dan.carpenter@oracle.com</email>
</author>
<published>2018-11-01T05:25:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9ae4f8420ed7be4b13c96600e3568c144d101a23'/>
<id>9ae4f8420ed7be4b13c96600e3568c144d101a23</id>
<content type='text'>
If "interface" is NULL then we can't release it and trying to will only
lead to an Oops.

Fixes: aea71a024914 ("[SCSI] bnx2fc: Introduce interface structure for each vlan interface")
Signed-off-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If "interface" is NULL then we can't release it and trying to will only
lead to an Oops.

Fixes: aea71a024914 ("[SCSI] bnx2fc: Introduce interface structure for each vlan interface")
Signed-off-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "scsi: qla2xxx: Fix NVMe Target discovery"</title>
<updated>2018-12-08T03:22:33+00:00</updated>
<author>
<name>Himanshu Madhani</name>
<email>hmadhani@marvell.com</email>
</author>
<published>2018-12-07T05:49:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c64a87f9518409d0a439895f09f6149ffdd427b8'/>
<id>c64a87f9518409d0a439895f09f6149ffdd427b8</id>
<content type='text'>
This reverts commit db186382af21e926e90df19499475f2552192b77.

This commit introduced regression with FCP discovery so revert it to fix
discovery for FCP luns.

Signed-off-by: Himanshu Madhani &lt;hmadhani@marvell.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit db186382af21e926e90df19499475f2552192b77.

This commit introduced regression with FCP discovery so revert it to fix
discovery for FCP luns.

Signed-off-by: Himanshu Madhani &lt;hmadhani@marvell.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi</title>
<updated>2018-12-06T01:06:31+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-12-06T01:06:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cf76c364a1e1e5224af80edf70a1e3023e1fcf8c'/>
<id>cf76c364a1e1e5224af80edf70a1e3023e1fcf8c</id>
<content type='text'>
Pull SCSI fixes from James Bottomley:
 "Four obvious bug fixes. The vmw_pscsi is so old that it's amazing
  no-one noticed before now"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: storvsc: Fix a race in sub-channel creation that can cause panic
  scsi: vmw_pscsi: Rearrange code to avoid multiple calls to free_irq during unload
  scsi: libiscsi: Fix NULL pointer dereference in iscsi_eh_session_reset
  scsi: lpfc: fix block guard enablement on SLI3 adapters
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull SCSI fixes from James Bottomley:
 "Four obvious bug fixes. The vmw_pscsi is so old that it's amazing
  no-one noticed before now"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: storvsc: Fix a race in sub-channel creation that can cause panic
  scsi: vmw_pscsi: Rearrange code to avoid multiple calls to free_irq during unload
  scsi: libiscsi: Fix NULL pointer dereference in iscsi_eh_session_reset
  scsi: lpfc: fix block guard enablement on SLI3 adapters
</pre>
</div>
</content>
</entry>
<entry>
<title>scsi: storvsc: Fix a race in sub-channel creation that can cause panic</title>
<updated>2018-11-29T02:33:16+00:00</updated>
<author>
<name>Dexuan Cui</name>
<email>decui@microsoft.com</email>
</author>
<published>2018-11-26T00:26:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c967590457cae5ba4f018704c341641bdcecfdcf'/>
<id>c967590457cae5ba4f018704c341641bdcecfdcf</id>
<content type='text'>
We can concurrently try to open the same sub-channel from 2 paths:

path #1: vmbus_onoffer() -&gt; vmbus_process_offer() -&gt; handle_sc_creation().
path #2: storvsc_probe() -&gt; storvsc_connect_to_vsp() -&gt;
	 -&gt; storvsc_channel_init() -&gt; handle_multichannel_storage() -&gt;
	 -&gt; vmbus_are_subchannels_present() -&gt; handle_sc_creation().

They conflict with each other, but it was not an issue before the recent
commit ae6935ed7d42 ("vmbus: split ring buffer allocation from open"),
because at the beginning of vmbus_open() we checked newchannel-&gt;state so
only one path could succeed, and the other would return with -EINVAL.

After ae6935ed7d42, the failing path frees the channel's ringbuffer by
vmbus_free_ring(), and this causes a panic later.

Commit ae6935ed7d42 itself is good, and it just reveals the longstanding
race. We can resolve the issue by removing path #2, i.e. removing the
second vmbus_are_subchannels_present() in handle_multichannel_storage().

BTW, the comment "Check to see if sub-channels have already been created"
in handle_multichannel_storage() is incorrect: when we unload the driver,
we first close the sub-channel(s) and then close the primary channel, next
the host sends rescind-offer message(s) so primary-&gt;sc_list will become
empty. This means the first vmbus_are_subchannels_present() in
handle_multichannel_storage() is never useful.

Fixes: ae6935ed7d42 ("vmbus: split ring buffer allocation from open")
Cc: stable@vger.kernel.org
Cc: Long Li &lt;longli@microsoft.com&gt;
Cc: Stephen Hemminger &lt;sthemmin@microsoft.com&gt;
Cc: K. Y. Srinivasan &lt;kys@microsoft.com&gt;
Cc: Haiyang Zhang &lt;haiyangz@microsoft.com&gt;
Signed-off-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Signed-off-by: K. Y. Srinivasan &lt;kys@microsoft.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We can concurrently try to open the same sub-channel from 2 paths:

path #1: vmbus_onoffer() -&gt; vmbus_process_offer() -&gt; handle_sc_creation().
path #2: storvsc_probe() -&gt; storvsc_connect_to_vsp() -&gt;
	 -&gt; storvsc_channel_init() -&gt; handle_multichannel_storage() -&gt;
	 -&gt; vmbus_are_subchannels_present() -&gt; handle_sc_creation().

They conflict with each other, but it was not an issue before the recent
commit ae6935ed7d42 ("vmbus: split ring buffer allocation from open"),
because at the beginning of vmbus_open() we checked newchannel-&gt;state so
only one path could succeed, and the other would return with -EINVAL.

After ae6935ed7d42, the failing path frees the channel's ringbuffer by
vmbus_free_ring(), and this causes a panic later.

Commit ae6935ed7d42 itself is good, and it just reveals the longstanding
race. We can resolve the issue by removing path #2, i.e. removing the
second vmbus_are_subchannels_present() in handle_multichannel_storage().

BTW, the comment "Check to see if sub-channels have already been created"
in handle_multichannel_storage() is incorrect: when we unload the driver,
we first close the sub-channel(s) and then close the primary channel, next
the host sends rescind-offer message(s) so primary-&gt;sc_list will become
empty. This means the first vmbus_are_subchannels_present() in
handle_multichannel_storage() is never useful.

Fixes: ae6935ed7d42 ("vmbus: split ring buffer allocation from open")
Cc: stable@vger.kernel.org
Cc: Long Li &lt;longli@microsoft.com&gt;
Cc: Stephen Hemminger &lt;sthemmin@microsoft.com&gt;
Cc: K. Y. Srinivasan &lt;kys@microsoft.com&gt;
Cc: Haiyang Zhang &lt;haiyangz@microsoft.com&gt;
Signed-off-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Signed-off-by: K. Y. Srinivasan &lt;kys@microsoft.com&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
</pre>
</div>
</content>
</entry>
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