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authorFlavio Leitner <fbl@redhat.com>2014-03-27 11:05:34 -0300
committerDavid S. Miller <davem@davemloft.net>2014-03-28 16:41:53 -0400
commit4f647e0a3c37b8d5086214128614a136064110c3 (patch)
tree32b03e568ed7e2c381de3b709a50161fbb3e6fe0
parent99b192da9c99284ad3374132e56f66995cadc6b4 (diff)
downloadlinux-linaro-stable-4f647e0a3c37b8d5086214128614a136064110c3.tar.gz
openvswitch: fix a possible deadlock and lockdep warning
There are two problematic situations. A deadlock can happen when is_percpu is false because it can get interrupted while holding the spinlock. Then it executes ovs_flow_stats_update() in softirq context which tries to get the same lock. The second sitation is that when is_percpu is true, the code correctly disables BH but only for the local CPU, so the following can happen when locking the remote CPU without disabling BH: CPU#0 CPU#1 ovs_flow_stats_get() stats_read() +->spin_lock remote CPU#1 ovs_flow_stats_get() | <interrupted> stats_read() | ... +--> spin_lock remote CPU#0 | | <interrupted> | ovs_flow_stats_update() | ... | spin_lock local CPU#0 <--+ ovs_flow_stats_update() +---------------------------------- spin_lock local CPU#1 This patch disables BH for both cases fixing the deadlocks. Acked-by: Jesse Gross <jesse@nicira.com> ================================= [ INFO: inconsistent lock state ] 3.14.0-rc8-00007-g632b06a #1 Tainted: G I --------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/0/0 [HC0[0]:SC1[5]:HE1:SE0] takes: (&(&cpu_stats->lock)->rlock){+.?...}, at: [<ffffffffa05dd8a1>] ovs_flow_stats_update+0x51/0xd0 [openvswitch] {SOFTIRQ-ON-W} state was registered at: [<ffffffff810f973f>] __lock_acquire+0x68f/0x1c40 [<ffffffff810fb4e2>] lock_acquire+0xa2/0x1d0 [<ffffffff817d8d9e>] _raw_spin_lock+0x3e/0x80 [<ffffffffa05dd9e4>] ovs_flow_stats_get+0xc4/0x1e0 [openvswitch] [<ffffffffa05da855>] ovs_flow_cmd_fill_info+0x185/0x360 [openvswitch] [<ffffffffa05daf05>] ovs_flow_cmd_build_info.constprop.27+0x55/0x90 [openvswitch] [<ffffffffa05db41d>] ovs_flow_cmd_new_or_set+0x4dd/0x570 [openvswitch] [<ffffffff816c245d>] genl_family_rcv_msg+0x1cd/0x3f0 [<ffffffff816c270e>] genl_rcv_msg+0x8e/0xd0 [<ffffffff816c0239>] netlink_rcv_skb+0xa9/0xc0 [<ffffffff816c0798>] genl_rcv+0x28/0x40 [<ffffffff816bf830>] netlink_unicast+0x100/0x1e0 [<ffffffff816bfc57>] netlink_sendmsg+0x347/0x770 [<ffffffff81668e9c>] sock_sendmsg+0x9c/0xe0 [<ffffffff816692d9>] ___sys_sendmsg+0x3a9/0x3c0 [<ffffffff8166a911>] __sys_sendmsg+0x51/0x90 [<ffffffff8166a962>] SyS_sendmsg+0x12/0x20 [<ffffffff817e3ce9>] system_call_fastpath+0x16/0x1b irq event stamp: 1740726 hardirqs last enabled at (1740726): [<ffffffff8175d5e0>] ip6_finish_output2+0x4f0/0x840 hardirqs last disabled at (1740725): [<ffffffff8175d59b>] ip6_finish_output2+0x4ab/0x840 softirqs last enabled at (1740674): [<ffffffff8109be12>] _local_bh_enable+0x22/0x50 softirqs last disabled at (1740675): [<ffffffff8109db05>] irq_exit+0xc5/0xd0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&cpu_stats->lock)->rlock); <Interrupt> lock(&(&cpu_stats->lock)->rlock); *** DEADLOCK *** 5 locks held by swapper/0/0: #0: (((&ifa->dad_timer))){+.-...}, at: [<ffffffff810a7155>] call_timer_fn+0x5/0x320 #1: (rcu_read_lock){.+.+..}, at: [<ffffffff81788a55>] mld_sendpack+0x5/0x4a0 #2: (rcu_read_lock_bh){.+....}, at: [<ffffffff8175d149>] ip6_finish_output2+0x59/0x840 #3: (rcu_read_lock_bh){.+....}, at: [<ffffffff8168ba75>] __dev_queue_xmit+0x5/0x9b0 #4: (rcu_read_lock){.+.+..}, at: [<ffffffffa05e41b5>] internal_dev_xmit+0x5/0x110 [openvswitch] stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Tainted: G I 3.14.0-rc8-00007-g632b06a #1 Hardware name: /DX58SO, BIOS SOX5810J.86A.5599.2012.0529.2218 05/29/2012 0000000000000000 0fcf20709903df0c ffff88042d603808 ffffffff817cfe3c ffffffff81c134c0 ffff88042d603858 ffffffff817cb6da 0000000000000005 ffffffff00000001 ffff880400000000 0000000000000006 ffffffff81c134c0 Call Trace: <IRQ> [<ffffffff817cfe3c>] dump_stack+0x4d/0x66 [<ffffffff817cb6da>] print_usage_bug+0x1f4/0x205 [<ffffffff810f7f10>] ? check_usage_backwards+0x180/0x180 [<ffffffff810f8963>] mark_lock+0x223/0x2b0 [<ffffffff810f96d3>] __lock_acquire+0x623/0x1c40 [<ffffffff810f5707>] ? __lock_is_held+0x57/0x80 [<ffffffffa05e26c6>] ? masked_flow_lookup+0x236/0x250 [openvswitch] [<ffffffff810fb4e2>] lock_acquire+0xa2/0x1d0 [<ffffffffa05dd8a1>] ? ovs_flow_stats_update+0x51/0xd0 [openvswitch] [<ffffffff817d8d9e>] _raw_spin_lock+0x3e/0x80 [<ffffffffa05dd8a1>] ? ovs_flow_stats_update+0x51/0xd0 [openvswitch] [<ffffffffa05dd8a1>] ovs_flow_stats_update+0x51/0xd0 [openvswitch] [<ffffffffa05dcc64>] ovs_dp_process_received_packet+0x84/0x120 [openvswitch] [<ffffffff810f93f7>] ? __lock_acquire+0x347/0x1c40 [<ffffffffa05e3bea>] ovs_vport_receive+0x2a/0x30 [openvswitch] [<ffffffffa05e4218>] internal_dev_xmit+0x68/0x110 [openvswitch] [<ffffffffa05e41b5>] ? internal_dev_xmit+0x5/0x110 [openvswitch] [<ffffffff8168b4a6>] dev_hard_start_xmit+0x2e6/0x8b0 [<ffffffff8168be87>] __dev_queue_xmit+0x417/0x9b0 [<ffffffff8168ba75>] ? __dev_queue_xmit+0x5/0x9b0 [<ffffffff8175d5e0>] ? ip6_finish_output2+0x4f0/0x840 [<ffffffff8168c430>] dev_queue_xmit+0x10/0x20 [<ffffffff8175d641>] ip6_finish_output2+0x551/0x840 [<ffffffff8176128a>] ? ip6_finish_output+0x9a/0x220 [<ffffffff8176128a>] ip6_finish_output+0x9a/0x220 [<ffffffff8176145f>] ip6_output+0x4f/0x1f0 [<ffffffff81788c29>] mld_sendpack+0x1d9/0x4a0 [<ffffffff817895b8>] mld_send_initial_cr.part.32+0x88/0xa0 [<ffffffff817691b0>] ? addrconf_dad_completed+0x220/0x220 [<ffffffff8178e301>] ipv6_mc_dad_complete+0x31/0x50 [<ffffffff817690d7>] addrconf_dad_completed+0x147/0x220 [<ffffffff817691b0>] ? addrconf_dad_completed+0x220/0x220 [<ffffffff8176934f>] addrconf_dad_timer+0x19f/0x1c0 [<ffffffff810a71e9>] call_timer_fn+0x99/0x320 [<ffffffff810a7155>] ? call_timer_fn+0x5/0x320 [<ffffffff817691b0>] ? addrconf_dad_completed+0x220/0x220 [<ffffffff810a76c4>] run_timer_softirq+0x254/0x3b0 [<ffffffff8109d47d>] __do_softirq+0x12d/0x480 Signed-off-by: Flavio Leitner <fbl@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/openvswitch/flow.c26
1 files changed, 6 insertions, 20 deletions
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index dda451f4429c..2998989e76db 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -103,30 +103,24 @@ static void stats_read(struct flow_stats *stats,
void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
unsigned long *used, __be16 *tcp_flags)
{
- int cpu, cur_cpu;
+ int cpu;
*used = 0;
*tcp_flags = 0;
memset(ovs_stats, 0, sizeof(*ovs_stats));
+ local_bh_disable();
if (!flow->stats.is_percpu) {
stats_read(flow->stats.stat, ovs_stats, used, tcp_flags);
} else {
- cur_cpu = get_cpu();
for_each_possible_cpu(cpu) {
struct flow_stats *stats;
- if (cpu == cur_cpu)
- local_bh_disable();
-
stats = per_cpu_ptr(flow->stats.cpu_stats, cpu);
stats_read(stats, ovs_stats, used, tcp_flags);
-
- if (cpu == cur_cpu)
- local_bh_enable();
}
- put_cpu();
}
+ local_bh_enable();
}
static void stats_reset(struct flow_stats *stats)
@@ -141,25 +135,17 @@ static void stats_reset(struct flow_stats *stats)
void ovs_flow_stats_clear(struct sw_flow *flow)
{
- int cpu, cur_cpu;
+ int cpu;
+ local_bh_disable();
if (!flow->stats.is_percpu) {
stats_reset(flow->stats.stat);
} else {
- cur_cpu = get_cpu();
-
for_each_possible_cpu(cpu) {
-
- if (cpu == cur_cpu)
- local_bh_disable();
-
stats_reset(per_cpu_ptr(flow->stats.cpu_stats, cpu));
-
- if (cpu == cur_cpu)
- local_bh_enable();
}
- put_cpu();
}
+ local_bh_enable();
}
static int check_header(struct sk_buff *skb, int len)