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Subject[78/89] rds: Make rds_sock_lock BH rather than IRQ safe.
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "David S. Miller" <davem@davemloft.net>

[ Upstream commit efc3dbc37412c027e363736b4f4c74ee5e8ecffc ]

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@chelsio.com>
Reported-by: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/rds/af_rds.c | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -68,7 +68,6 @@ static int rds_release(struct socket *so
{
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 *so
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_

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 *s
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 soc
{
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 soc
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
{
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)



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