bpf: Add test_tag to .gitignore - net-next.git

path: root/tools/testing/selftests/seccomp

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author	Mickaël Salaün <mic@digikod.net>	2017-02-10 00:21:45 +0100
committer	David S. Miller <davem@davemloft.net>	2017-02-10 15:56:08 -0500
commit	bc6a3d9977b6ea093cd7c567ef83657023e77f26 (patch)
tree	818554b86ad5f16649551345ad4a7abdf8128738 /tools/testing/selftests/seccomp
parent	702498a1426bc95b6f49f9c5fba616110cbd3947 (diff)

bpf: Add test_tag to .gitignore

Signed-off-by: Mickaël Salaün <mic@digikod.net> Cc: Alexei Starovoitov <ast@fb.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>

Diffstat (limited to 'tools/testing/selftests/seccomp')

0 files changed, 0 insertions, 0 deletions

32/0x280 [<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>

Diffstat (limited to 'net/tipc/net.h')


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