[kernel/f16] Backport patch to fix oops in rds (rhbz 718790)

[Josh Boyer]

commit fb68683a8ff418b75a8088761feffbbd6e71c2a0
Author: Josh Boyer <jwboyer at redhat.com>
Date:   Tue Jan 24 22:48:56 2012 -0500

    Backport patch to fix oops in rds (rhbz 718790)

 kernel.spec                                        |    9 ++
 ...ake-rds_sock_lock-BH-rather-than-IRQ-safe.patch |  116 ++++++++++++++++++++
 2 files changed, 125 insertions(+), 0 deletions(-)
---
diff --git a/kernel.spec b/kernel.spec
index 95da156..b7a4ec6 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -817,6 +817,9 @@ Patch21228: SCSI-sym53c8xx-Fix-NULL-pointer-dereference-in-slave.patch
 #rhbz 766071
 Patch21229: iwlagn-check-for-SMPS-mode.patch
 
+#rhbz 718790
+Patch21230: rds-Make-rds_sock_lock-BH-rather-than-IRQ-safe.patch
+
 Patch22000: rcu-reintroduce-missing-calls.patch
 
 
@@ -1521,6 +1524,9 @@ ApplyPatch iwlagn-check-for-SMPS-mode.patch
 
 ApplyPatch rcu-reintroduce-missing-calls.patch
 
+#rhbz 718790
+ApplyPatch rds-Make-rds_sock_lock-BH-rather-than-IRQ-safe.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2292,6 +2298,9 @@ fi
 # and build.
 
 %changelog
+* Wed Jan 25 2012 Josh Boyer <jwboyer at redhat.com>
+- Backport patch to fix oops in rds (rhbz 718790)
+
 * Tue Jan 24 2012 John W. Linville <linville at redhat.com>
 - Update compat-wireless snapshot to version 3.3-rc1-2
 
diff --git a/rds-Make-rds_sock_lock-BH-rather-than-IRQ-safe.patch b/rds-Make-rds_sock_lock-BH-rather-than-IRQ-safe.patch
new file mode 100644
index 0000000..0946aad
--- /dev/null
+++ b/rds-Make-rds_sock_lock-BH-rather-than-IRQ-safe.patch
@@ -0,0 +1,116 @@
+From efc3dbc37412c027e363736b4f4c74ee5e8ecffc Mon Sep 17 00:00:00 2001
+From: "David S. Miller" <davem at davemloft.net>
+Date: Tue, 24 Jan 2012 17:03:44 -0500
+Subject: [PATCH] rds: Make rds_sock_lock BH rather than IRQ safe.
+
+rds_sock_info() triggers locking warnings because we try to perform a
+local_bh_enable() (via sock_i_ino()) while hardware interrupts are
+disabled (via taking rds_sock_lock).
+
+There is no reason for rds_sock_lock to be a hardware IRQ disabling
+lock, none of these access paths run in hardware interrupt context.
+
+Therefore making it a BH disabling lock is safe and sufficient to
+fix this bug.
+
+Reported-by: Kumar Sanghvi <kumaras at chelsio.com>
+Reported-by: Josh Boyer <jwboyer at gmail.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ net/rds/af_rds.c |   20 ++++++++------------
+ 1 files changed, 8 insertions(+), 12 deletions(-)
+
+diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
+index bb6ad81..424ff62 100644
+--- a/net/rds/af_rds.c
++++ b/net/rds/af_rds.c
+@@ -68,7 +68,6 @@ static int rds_release(struct socket *sock)
+ {
+ 	struct sock *sk = sock->sk;
+ 	struct rds_sock *rs;
+-	unsigned long flags;
+ 
+ 	if (!sk)
+ 		goto out;
+@@ -94,10 +93,10 @@ static int rds_release(struct socket *sock)
+ 	rds_rdma_drop_keys(rs);
+ 	rds_notify_queue_get(rs, NULL);
+ 
+-	spin_lock_irqsave(&rds_sock_lock, flags);
++	spin_lock_bh(&rds_sock_lock);
+ 	list_del_init(&rs->rs_item);
+ 	rds_sock_count--;
+-	spin_unlock_irqrestore(&rds_sock_lock, flags);
++	spin_unlock_bh(&rds_sock_lock);
+ 
+ 	rds_trans_put(rs->rs_transport);
+ 
+@@ -409,7 +408,6 @@ static const struct proto_ops rds_proto_ops = {
+ 
+ static int __rds_create(struct socket *sock, struct sock *sk, int protocol)
+ {
+-	unsigned long flags;
+ 	struct rds_sock *rs;
+ 
+ 	sock_init_data(sock, sk);
+@@ -426,10 +424,10 @@ static int __rds_create(struct socket *sock, struct sock *sk, int protocol)
+ 	spin_lock_init(&rs->rs_rdma_lock);
+ 	rs->rs_rdma_keys = RB_ROOT;
+ 
+-	spin_lock_irqsave(&rds_sock_lock, flags);
++	spin_lock_bh(&rds_sock_lock);
+ 	list_add_tail(&rs->rs_item, &rds_sock_list);
+ 	rds_sock_count++;
+-	spin_unlock_irqrestore(&rds_sock_lock, flags);
++	spin_unlock_bh(&rds_sock_lock);
+ 
+ 	return 0;
+ }
+@@ -471,12 +469,11 @@ static void rds_sock_inc_info(struct socket *sock, unsigned int len,
+ {
+ 	struct rds_sock *rs;
+ 	struct rds_incoming *inc;
+-	unsigned long flags;
+ 	unsigned int total = 0;
+ 
+ 	len /= sizeof(struct rds_info_message);
+ 
+-	spin_lock_irqsave(&rds_sock_lock, flags);
++	spin_lock_bh(&rds_sock_lock);
+ 
+ 	list_for_each_entry(rs, &rds_sock_list, rs_item) {
+ 		read_lock(&rs->rs_recv_lock);
+@@ -492,7 +489,7 @@ static void rds_sock_inc_info(struct socket *sock, unsigned int len,
+ 		read_unlock(&rs->rs_recv_lock);
+ 	}
+ 
+-	spin_unlock_irqrestore(&rds_sock_lock, flags);
++	spin_unlock_bh(&rds_sock_lock);
+ 
+ 	lens->nr = total;
+ 	lens->each = sizeof(struct rds_info_message);
+@@ -504,11 +501,10 @@ static void rds_sock_info(struct socket *sock, unsigned int len,
+ {
+ 	struct rds_info_socket sinfo;
+ 	struct rds_sock *rs;
+-	unsigned long flags;
+ 
+ 	len /= sizeof(struct rds_info_socket);
+ 
+-	spin_lock_irqsave(&rds_sock_lock, flags);
++	spin_lock_bh(&rds_sock_lock);
+ 
+ 	if (len < rds_sock_count)
+ 		goto out;
+@@ -529,7 +525,7 @@ out:
+ 	lens->nr = rds_sock_count;
+ 	lens->each = sizeof(struct rds_info_socket);
+ 
+-	spin_unlock_irqrestore(&rds_sock_lock, flags);
++	spin_unlock_bh(&rds_sock_lock);
+ }
+ 
+ static void rds_exit(void)
+-- 
+1.7.7.6
+