[3.8.y.z extended stable] Patch "IB/srp: Remove target from list before freeing Scsi_Host structure" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    IB/srp: Remove target from list before freeing Scsi_Host structure

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.14.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f9f1cee88bf9bc23ce15c9fd2b3a4d22055863c3 Mon Sep 17 00:00:00 2001
From: Vu Pham <vuhuong at mellanox.com>
Date: Thu, 10 Oct 2013 13:50:29 +0200
Subject: IB/srp: Remove target from list before freeing Scsi_Host structure

commit 65d7dd2f3479ef5aec1d9ddd1481cb7851c11af6 upstream.

Remove an SRP target from the SRP target list before invoking the last
scsi_host_put() call.  This change is necessary because that last put
frees the memory that holds the srp_target_port structure.

This patch prevents the following kernel oops:

    RIP: 0010:[<ffffffff810b00d0>] __lock_acquire+0x500/0x1570
    Call Trace:
     [<ffffffff810b11e4>] lock_acquire+0xa4/0x120
     [<ffffffff81531206>] _spin_lock+0x36/0x70
     [<ffffffffa01b6d8f>] srp_remove_work+0xef/0x180 [ib_srp]
     [<ffffffff8109125c>] worker_thread+0x21c/0x3d0
     [<ffffffff81096e86>] kthread+0x96/0xa0
     [<ffffffff8100c20a>] child_rip+0xa/0x20

Signed-off-by: Vu Pham <vuhuong at mellanox.com>

[ bvanassche - Modified path description and CC'ed stable. ]

Signed-off-by: Bart Van Assche <bvanassche at acm.org>
Signed-off-by: Roland Dreier <roland at purestorage.com>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 7ccf328..2223eb6 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -532,6 +532,11 @@ static void srp_remove_target(struct srp_target_port *target)
 	ib_destroy_cm_id(target->cm_id);
 	srp_free_target_ib(target);
 	srp_free_req_data(target);
+
+	spin_lock(&target->srp_host->target_lock);
+	list_del(&target->list);
+	spin_unlock(&target->srp_host->target_lock);
+
 	scsi_host_put(target->scsi_host);
 }

@@ -542,10 +547,6 @@ static void srp_remove_work(struct work_struct *work)

 	WARN_ON_ONCE(target->state != SRP_TARGET_REMOVED);

-	spin_lock(&target->srp_host->target_lock);
-	list_del(&target->list);
-	spin_unlock(&target->srp_host->target_lock);
-
 	srp_remove_target(target);
 }

--
1.8.3.2