[PATCH 1/3] IB/srp: Remove target from list before freeing Scsi_Host structure

[Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>]

From: Vu Pham <vuhuong-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

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 that the following kernel oops can be triggered:

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-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
[bvanassche: Modified path description and CC'ed stable]
Signed-off-by: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
Cc: David Dillow <dillowda-1Heg1YXhbW8@public.gmane.org>
Cc: Roland Dreier <roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Sebastian Riemer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
Cc: Jack Wang <jinpu.wang-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
---
 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 f93baf8..f1318a8 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)
-- 
1.8.1.4

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