[ 34/47] pktgen: fix crash at module unload

Greg KH
2012-06-07T04:25:39Z

From: Eric Dumazet <eric.dumazet@gmail.com>

[ Upstream commit c57b54684060c8aced64a5b78ff69ff289af97b9 ]

commit 7d3d43dab4e9 (net: In unregister_netdevice_notifier unregister
the netdevices.) makes pktgen crashing at module unload.

[ 296.820578] BUG: spinlock bad magic on CPU#6, rmmod/3267
[ 296.820719] lock: ffff880310c38000, .magic: ffff8803, .owner: <none>/-1, .owner_cpu: -1
[ 296.820943] Pid: 3267, comm: rmmod Not tainted 3.4.0-rc5+ #254
[ 296.821079] Call Trace:
[ 296.821211] [<ffffffff8168a715>] spin_dump+0x8a/0x8f
[ 296.821345] [<ffffffff8168a73b>] spin_bug+0x21/0x26
[ 296.821507] [<ffffffff812b4741>] do_raw_spin_lock+0x131/0x140
[ 296.821648] [<ffffffff8169188e>] _raw_spin_lock+0x1e/0x20
[ 296.821786] [<ffffffffa00cc0fd>] __pktgen_NN_threads+0x4d/0x140 [pktgen]
[ 296.821928] [<ffffffffa00ccf8d>] pktgen_device_event+0x10d/0x1e0 [pktgen]
[ 296.822073] [<ffffffff8154ed4f>] unregister_netdevice_notifier+0x7f/0x100
[ 296.822216] [<ffffffffa00d2a0b>] pg_cleanup+0x48/0x73 [pktgen]
[ 296.822357] [<ffffffff8109528e>] sys_delete_module+0x17e/0x2a0
[ 296.822502] [<ffffffff81699652>] system_call_fastpath+0x16/0x1b

Hold the pktgen_thread_lock while splicing pktgen_threads, and test
pktgen_exiting in pktgen_device_event() to make unload faster.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/pktgen.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -1932,7 +1932,7 @@ static int pktgen_device_event(struct no
{
struct net_device *dev = ptr;

- if (!net_eq(dev_net(dev), &init_net))
+ if (!net_eq(dev_net(dev), &init_net) || pktgen_exiting)
return NOTIFY_DONE;

/* It is OK that we do not hold the group lock right now,
@@ -3755,12 +3755,18 @@ static void __exit pg_cleanup(void)
{
struct pktgen_thread *t;
struct list_head *q, *n;
+ struct list_head list;

/* Stop all interfaces & threads */
pktgen_exiting = true;

- list_for_each_safe(q, n, &pktgen_threads) {
+ mutex_lock(&pktgen_thread_lock);
+ list_splice(&list, &pktgen_threads);
+ mutex_unlock(&pktgen_thread_lock);
+
+ list_for_each_safe(q, n, &list) {
t = list_entry(q, struct pktgen_thread, th_list);
+ list_del(&t->th_list);
kthread_stop(t->tsk);
kfree(t);
}