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authorYing Xue <ying.xue@windriver.com>2012-08-16 12:09:07 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-09-14 05:50:48 -0700
commit49b74a1aebc95914fff369b746ce13558eb9063f (patch)
parent2eeeacf627ab4bac67c3c1735b2c96fccbea6262 (diff)
tipc: fix lockdep warning during bearer initialization
[ Upstream commit 4225a398c1352a7a5c14dc07277cb5cc4473983b ] When the lockdep validator is enabled, it will report the below warning when we enable a TIPC bearer: [ INFO: possible irq lock inversion dependency detected ] --------------------------------------------------------- Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ptype_lock); local_irq_disable(); lock(tipc_net_lock); lock(ptype_lock); <Interrupt> lock(tipc_net_lock); *** DEADLOCK *** the shortest dependencies between 2nd lock and 1st lock: -> (ptype_lock){+.+...} ops: 10 { [...] SOFTIRQ-ON-W at: [<c1089418>] __lock_acquire+0x528/0x13e0 [<c108a360>] lock_acquire+0x90/0x100 [<c1553c38>] _raw_spin_lock+0x38/0x50 [<c14651ca>] dev_add_pack+0x3a/0x60 [<c182da75>] arp_init+0x1a/0x48 [<c182dce5>] inet_init+0x181/0x27e [<c1001114>] do_one_initcall+0x34/0x170 [<c17f7329>] kernel_init+0x110/0x1b2 [<c155b6a2>] kernel_thread_helper+0x6/0x10 [...] ... key at: [<c17e4b10>] ptype_lock+0x10/0x20 ... acquired at: [<c108a360>] lock_acquire+0x90/0x100 [<c1553c38>] _raw_spin_lock+0x38/0x50 [<c14651ca>] dev_add_pack+0x3a/0x60 [<c8bc18d2>] enable_bearer+0xf2/0x140 [tipc] [<c8bb283a>] tipc_enable_bearer+0x1ba/0x450 [tipc] [<c8bb3a04>] tipc_cfg_do_cmd+0x5c4/0x830 [tipc] [<c8bbc032>] handle_cmd+0x42/0xd0 [tipc] [<c148e802>] genl_rcv_msg+0x232/0x280 [<c148d3f6>] netlink_rcv_skb+0x86/0xb0 [<c148e5bc>] genl_rcv+0x1c/0x30 [<c148d144>] netlink_unicast+0x174/0x1f0 [<c148ddab>] netlink_sendmsg+0x1eb/0x2d0 [<c1456bc1>] sock_aio_write+0x161/0x170 [<c1135a7c>] do_sync_write+0xac/0xf0 [<c11360f6>] vfs_write+0x156/0x170 [<c11361e2>] sys_write+0x42/0x70 [<c155b0df>] sysenter_do_call+0x12/0x38 [...] } -> (tipc_net_lock){+..-..} ops: 4 { [...] IN-SOFTIRQ-R at: [<c108953a>] __lock_acquire+0x64a/0x13e0 [<c108a360>] lock_acquire+0x90/0x100 [<c15541cd>] _raw_read_lock_bh+0x3d/0x50 [<c8bb874d>] tipc_recv_msg+0x1d/0x830 [tipc] [<c8bc195f>] recv_msg+0x3f/0x50 [tipc] [<c146a5fa>] __netif_receive_skb+0x22a/0x590 [<c146ab0b>] netif_receive_skb+0x2b/0xf0 [<c13c43d2>] pcnet32_poll+0x292/0x780 [<c146b00a>] net_rx_action+0xfa/0x1e0 [<c103a4be>] __do_softirq+0xae/0x1e0 [...] } >From the log, we can see three different call chains between CPU0 and CPU1: Time 0 on CPU0: kernel_init()->inet_init()->dev_add_pack() At time 0, the ptype_lock is held by CPU0 in dev_add_pack(); Time 1 on CPU1: tipc_enable_bearer()->enable_bearer()->dev_add_pack() At time 1, tipc_enable_bearer() first holds tipc_net_lock, and then wants to take ptype_lock to register TIPC protocol handler into the networking stack. But the ptype_lock has been taken by dev_add_pack() on CPU0, so at this time the dev_add_pack() running on CPU1 has to be busy looping. Time 2 on CPU0: netif_receive_skb()->recv_msg()->tipc_recv_msg() At time 2, an incoming TIPC packet arrives at CPU0, hence tipc_recv_msg() will be invoked. In tipc_recv_msg(), it first wants to hold tipc_net_lock. At the moment, below scenario happens: On CPU0, below is our sequence of taking locks: lock(ptype_lock)->lock(tipc_net_lock) On CPU1, our sequence of taking locks looks like: lock(tipc_net_lock)->lock(ptype_lock) Obviously deadlock may happen in this case. But please note the deadlock possibly doesn't occur at all when the first TIPC bearer is enabled. Before enable_bearer() -- running on CPU1 does not hold ptype_lock, so the TIPC receive handler (i.e. recv_msg()) is not registered successfully via dev_add_pack(), so the tipc_recv_msg() cannot be called by recv_msg() even if a TIPC message comes to CPU0. But when the second TIPC bearer is registered, the deadlock can perhaps really happen. To fix it, we will push the work of registering TIPC protocol handler into workqueue context. After the change, both paths taking ptype_lock are always in process contexts, thus, the deadlock should never occur. Signed-off-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 14 insertions, 1 deletions
diff --git a/net/tipc/eth_media.c b/net/tipc/eth_media.c
index b69092eb95d8..a8c2a6b2dda7 100644
--- a/net/tipc/eth_media.c
+++ b/net/tipc/eth_media.c
@@ -53,6 +53,7 @@ struct eth_bearer {
struct tipc_bearer *bearer;
struct net_device *dev;
struct packet_type tipc_packet_type;
+ struct work_struct setup;
static struct eth_bearer eth_bearers[MAX_ETH_BEARERS];
@@ -121,6 +122,17 @@ static int recv_msg(struct sk_buff *buf, struct net_device *dev,
+ * setup_bearer - setup association between Ethernet bearer and interface
+ */
+static void setup_bearer(struct work_struct *work)
+ struct eth_bearer *eb_ptr =
+ container_of(work, struct eth_bearer, setup);
+ dev_add_pack(&eb_ptr->tipc_packet_type);
* enable_bearer - attach TIPC bearer to an Ethernet interface
@@ -167,7 +179,8 @@ static int enable_bearer(struct tipc_bearer *tb_ptr)
eb_ptr->tipc_packet_type.af_packet_priv = eb_ptr;
- dev_add_pack(&eb_ptr->tipc_packet_type);
+ INIT_WORK(&eb_ptr->setup, setup_bearer);
+ schedule_work(&eb_ptr->setup);
/* Associate TIPC bearer with Ethernet bearer */