From: Jesse Larrew <jlarrew@redhat.com>
Date: Wed, 5 Nov 2008 23:22:02 -0500
Subject: [openib] ehca: deadlock race when creating small queues
Message-id: 20081106042127.3677.44866.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.3 BZ470137] IB/ehca: Possible deadlock during creation of small queues.
Bugzilla: 470137
RH-Acked-by: Doug Ledford <dledford@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=470137

Description:
===========
This is a bugfix for the Infiniband/ehca driver on Power architectures.

In an error path of create_small_queues(), there is a mutex_unlock()
missing. This could lead to a deadlock in the ehca driver.

This patch simply adds the missing mutex_unlock(). It was accepted by
the community and is now in linux-2.6.27 kernel.

RHEL Version Found:
================
RHEL 5.3

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1560678

Upstream Status:
================
Here is the link to the LKML post:
http://lkml.org/lkml/2008/7/21/48

Here is the upstream commit:
commit 1a867c33bb65f2921351a9bdd98548bb96f0ff8c
http://kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.27

Test Status:
============
This is untested.

===============================================================

Jesse Larrew
IBM Onsite Partner
Office: 978-392-3183
Mobile: 512-791-4852
jlarrew@redhat.com
jlarrew@linux.vnet.ibm.com

Proposed Patch:
===============
This patch is based on 2.6.18-122.el5.

diff --git a/drivers/infiniband/hw/ehca/ipz_pt_fn.c b/drivers/infiniband/hw/ehca/ipz_pt_fn.c
index 661f8db..c3a3284 100644
--- a/drivers/infiniband/hw/ehca/ipz_pt_fn.c
+++ b/drivers/infiniband/hw/ehca/ipz_pt_fn.c
@@ -163,6 +163,7 @@ static int alloc_small_queue_page(struct ipz_queue *queue, struct ehca_pd *pd)
 
 out:
 	ehca_err(pd->ib_pd.device, "failed to allocate small queue page");
+	mutex_unlock(&pd->lock);
 	return 0;
 }