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authorYing Xue <ying.xue@windriver.com>2018-10-11 19:57:56 +0800
committerDavid S. Miller <davem@davemloft.net>2018-10-11 10:23:48 -0700
commita1f8dd34e64af689e95122921fb2ca83dedd4c4e (patch)
tree8dfdb208e28b52510f57e66f4d4156381f312504 /net/tipc
parent26b1f4cb9150ac9662063a3bdc3c0a44bf622981 (diff)
downloadlinux-stericsson-a1f8dd34e64af689e95122921fb2ca83dedd4c4e.tar.gz
tipc: eliminate possible recursive locking detected by LOCKDEP
When booting kernel with LOCKDEP option, below warning info was found: WARNING: possible recursive locking detected 4.19.0-rc7+ #14 Not tainted -------------------------------------------- swapper/0/1 is trying to acquire lock: 00000000dcfc0fc8 (&(&list->lock)->rlock#4){+...}, at: spin_lock_bh include/linux/spinlock.h:334 [inline] 00000000dcfc0fc8 (&(&list->lock)->rlock#4){+...}, at: tipc_link_reset+0x125/0xdf0 net/tipc/link.c:850 but task is already holding lock: 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at: spin_lock_bh include/linux/spinlock.h:334 [inline] 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at: tipc_link_reset+0xfa/0xdf0 net/tipc/link.c:849 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&list->lock)->rlock#4); lock(&(&list->lock)->rlock#4); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by swapper/0/1: #0: 00000000f7539d34 (pernet_ops_rwsem){+.+.}, at: register_pernet_subsys+0x19/0x40 net/core/net_namespace.c:1051 #1: 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at: spin_lock_bh include/linux/spinlock.h:334 [inline] #1: 00000000cbb9b036 (&(&list->lock)->rlock#4){+...}, at: tipc_link_reset+0xfa/0xdf0 net/tipc/link.c:849 stack backtrace: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc7+ #14 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1af/0x295 lib/dump_stack.c:113 print_deadlock_bug kernel/locking/lockdep.c:1759 [inline] check_deadlock kernel/locking/lockdep.c:1803 [inline] validate_chain kernel/locking/lockdep.c:2399 [inline] __lock_acquire+0xf1e/0x3c60 kernel/locking/lockdep.c:3411 lock_acquire+0x1db/0x520 kernel/locking/lockdep.c:3900 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [inline] tipc_link_reset+0x125/0xdf0 net/tipc/link.c:850 tipc_link_bc_create+0xb5/0x1f0 net/tipc/link.c:526 tipc_bcast_init+0x59b/0xab0 net/tipc/bcast.c:521 tipc_init_net+0x472/0x610 net/tipc/core.c:82 ops_init+0xf7/0x520 net/core/net_namespace.c:129 __register_pernet_operations net/core/net_namespace.c:940 [inline] register_pernet_operations+0x453/0xac0 net/core/net_namespace.c:1011 register_pernet_subsys+0x28/0x40 net/core/net_namespace.c:1052 tipc_init+0x83/0x104 net/tipc/core.c:140 do_one_initcall+0x109/0x70a init/main.c:885 do_initcall_level init/main.c:953 [inline] do_initcalls init/main.c:961 [inline] do_basic_setup init/main.c:979 [inline] kernel_init_freeable+0x4bd/0x57f init/main.c:1144 kernel_init+0x13/0x180 init/main.c:1063 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 The reason why the noise above was complained by LOCKDEP is because we nested to hold l->wakeupq.lock and l->inputq->lock in tipc_link_reset function. In fact it's unnecessary to move skb buffer from l->wakeupq queue to l->inputq queue while holding the two locks at the same time. Instead, we can move skb buffers in l->wakeupq queue to a temporary list first and then move the buffers of the temporary list to l->inputq queue, which is also safe for us. Fixes: 3f32d0be6c16 ("tipc: lock wakeup & inputq at tipc_link_reset()") Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Ying Xue <ying.xue@windriver.com> Acked-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/tipc')
-rw-r--r--net/tipc/link.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/net/tipc/link.c b/net/tipc/link.c
index d229a36968da..f6552e4f4b43 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -845,14 +845,21 @@ static void link_prepare_wakeup(struct tipc_link *l)
void tipc_link_reset(struct tipc_link *l)
{
+ struct sk_buff_head list;
+
+ __skb_queue_head_init(&list);
+
l->in_session = false;
l->session++;
l->mtu = l->advertised_mtu;
+
spin_lock_bh(&l->wakeupq.lock);
+ skb_queue_splice_init(&l->wakeupq, &list);
+ spin_unlock_bh(&l->wakeupq.lock);
+
spin_lock_bh(&l->inputq->lock);
- skb_queue_splice_init(&l->wakeupq, l->inputq);
+ skb_queue_splice_init(&list, l->inputq);
spin_unlock_bh(&l->inputq->lock);
- spin_unlock_bh(&l->wakeupq.lock);
__skb_queue_purge(&l->transmq);
__skb_queue_purge(&l->deferdq);