diff mbox series

ibmvfc: Protect vhost->task_set increment by the host lock

Message ID 1600286999-22059-1-git-send-email-brking@linux.vnet.ibm.com
State New
Headers show
Series ibmvfc: Protect vhost->task_set increment by the host lock | expand

Commit Message

Brian King Sept. 16, 2020, 8:09 p.m. UTC
In the discovery thread, ibmvfc does a vhost->task_set++ without
any lock held. This could result in two targets getting the same
cancel key, which could have strange effects in error recovery.
The actual probability of this occurring should be extremely
small, since this should all be done in a single threaded loop
from the discovery thread, but let's fix it up anyway to be safe.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvfc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Martin K. Petersen Sept. 22, 2020, 9:39 p.m. UTC | #1
Brian,

> In the discovery thread, ibmvfc does a vhost->task_set++ without any

> lock held. This could result in two targets getting the same cancel

> key, which could have strange effects in error recovery.  The actual

> probability of this occurring should be extremely small, since this

> should all be done in a single threaded loop from the discovery

> thread, but let's fix it up anyway to be safe.


Applied to 5.10/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering
Martin K. Petersen Sept. 30, 2020, 3:34 a.m. UTC | #2
On Wed, 16 Sep 2020 15:09:59 -0500, Brian King wrote:

> In the discovery thread, ibmvfc does a vhost->task_set++ without
> any lock held. This could result in two targets getting the same
> cancel key, which could have strange effects in error recovery.
> The actual probability of this occurring should be extremely
> small, since this should all be done in a single threaded loop
> from the discovery thread, but let's fix it up anyway to be safe.

Applied to 5.10/scsi-queue, thanks!

[1/1] scsi: ibmvfc: Protect vhost->task_set increment by the host lock
      https://git.kernel.org/mkp/scsi/c/2584e5aef87a
diff mbox series

Patch

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 322bb30..b393587 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -4169,11 +4169,11 @@  static int ibmvfc_alloc_target(struct ibmvfc_host *vhost,struct ibmvfc_discover_
 	tgt->wwpn = wwpn;
 	tgt->vhost = vhost;
 	tgt->need_login = 1;
-	tgt->cancel_key = vhost->task_set++;
 	timer_setup(&tgt->timer, ibmvfc_adisc_timeout, 0);
 	kref_init(&tgt->kref);
 	ibmvfc_init_tgt(tgt, ibmvfc_tgt_implicit_logout);
 	spin_lock_irqsave(vhost->host->host_lock, flags);
+	tgt->cancel_key = vhost->task_set++;
 	list_add_tail(&tgt->queue, &vhost->targets);
 
 unlock_out: