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

[Luis Henriques]

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-3.11.y-queue branch of the 3.11.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-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 805cc53854ab9ac3742969105ef17dab46e127e1 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>
Signed-off-by: Luis Henriques <luis.henriques 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 df7a19c..bc003a5 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -534,6 +534,11 @@ 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);
 }

@@ -545,10 +550,6 @@ static void srp_remove_work(struct work_struct *work)
 	WARN_ON_ONCE(target->state != SRP_TARGET_REMOVED);

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

 static void srp_rport_delete(struct srp_rport *rport)
--
1.8.3.2