[ATM]: avoid race conditions related to atm_devs list

Use semaphore to protect atm_devs list, as no one need access to it from
interrupt context.  Avoid race conditions between atm_dev_register(),
atm_dev_lookup() and atm_dev_deregister().  Fix double spin_unlock() bug.

Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/atm/common.c b/net/atm/common.c
index db9318fc6031..9e016f404e14 100644
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -427,12 +427,12 @@ int vcc_connect(struct socket *sock, int itf, short vpi, int vci)
                 dev = try_then_request_module(atm_dev_lookup(itf), "atm-device-%d", itf);
         } else {
                 dev = NULL;
-                spin_lock(&atm_dev_lock);
+                down(&atm_dev_mutex);
                 if (!list_empty(&atm_devs)) {
                         dev = list_entry(atm_devs.next, struct atm_dev, dev_list);
                         atm_dev_hold(dev);
                 }
-                spin_unlock(&atm_dev_lock);
+                up(&atm_dev_mutex);
         }
         if (!dev)
                 return -ENODEV;