netconsole: don't call __netpoll_cleanup() while atomic

[ Upstream commit 3f315bef23075ea8a98a6fe4221a83b83456d970 ]

__netpoll_cleanup() is called in netconsole_netdev_event() while holding a
spinlock. Release/acquire the spinlock before/after it and restart the
loop. Also, disable the netconsole completely, because we won't have chance
after the restart of the loop, and might end up in a situation where
nt->enabled == 1 and nt->np.dev == NULL.

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 6989ebe2bc7902c44e429dfefda4c432d3eb7131..21a942c1ed7b3e16ac414b05e043736bad0852bf 100644 (file)
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -630,6 +630,7 @@ static int netconsole_netdev_event(struct notifier_block *this,
                goto done;
 
        spin_lock_irqsave(&target_list_lock, flags);
+restart:
        list_for_each_entry(nt, &target_list, list) {
                netconsole_target_get(nt);
                if (nt->np.dev == dev) {
@@ -642,15 +643,17 @@ static int netconsole_netdev_event(struct notifier_block *this,
                        case NETDEV_UNREGISTER:
                                /*
                                 * rtnl_lock already held
+                                * we might sleep in __netpoll_cleanup()
                                 */
-                               if (nt->np.dev) {
-                                       __netpoll_cleanup(&nt->np);
-                                       dev_put(nt->np.dev);
-                                       nt->np.dev = NULL;
-                               }
+                               spin_unlock_irqrestore(&target_list_lock, flags);
+                               __netpoll_cleanup(&nt->np);
+                               spin_lock_irqsave(&target_list_lock, flags);
+                               dev_put(nt->np.dev);
+                               nt->np.dev = NULL;
                                nt->enabled = 0;
                                stopped = true;
-                               break;
+                               netconsole_target_put(nt);
+                               goto restart;
                        }
                }
                netconsole_target_put(nt);