datapath: Fix deadlock during stats update.

Stats-read needs to lock stats but same lock is taken in stats update in irq context. Therefore it needs to disable irq to avoid following deadlock :- BUG: soft lockup - CPU#1 stuck for 23s! [ovs-vswitchd:1425] CPU 1 Pid: 1425, comm: ovs-vswitchd Tainted: G O 3.2.39-server-nn23 openvswitch#1 VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform RIP: 0010:[<ffffffff8103db22>] [<ffffffff8103db22>] __ticket_spin_lock+0x22/0x30 RSP: 0018:ffff88003fd03b30 EFLAGS: 00000297 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000050 RDX: 0000000000000002 RSI: ffff88003d0a9900 RDI: ffff88003ae19598 RBP: ffff88003fd03b30 R08: 0000000000000000 R09: ffff88003ad44048 R10: 0000000000000001 R11: 0000000000000001 R12: ffff88003fd03aa8 R13: ffffffff8164e5de R14: ffff88003fd03b30 R15: ffff88003ae19580 FS: 00007ffb0b428940(0000) GS:ffff88003fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3c0ef94000 CR3: 00000000250e2000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process ovs-vswitchd (pid: 1425, threadinfo ffff88002514a000, task ffff8800250aae00) Stack: ffff88003fd03b40 ffffffff8164596e ffff88003fd03b70 ffffffffa027622d ffff88003d0a9900 ffffe8ffffd03800 ffff8800297f5a80 ffff88003fd03ba8 ffff88003fd03c60 ffffffffa02759af ffff88003fd03de0 ffff88003fd03e4c Call Trace: <IRQ> [<ffffffff8164596e>] _raw_spin_lock+0xe/0x20 [<ffffffffa027622d>] ovs_flow_stats_update+0x5d/0x100 [openvswitch] [<ffffffffa02759af>] ovs_dp_process_received_packet+0x8f/0x130 [openvswitch] [<ffffffffa027c0ca>] ovs_vport_receive+0x2a/0x30 [openvswitch] [<ffffffffa027db18>] netdev_frame_hook+0xb8/0x120 [openvswitch] [<ffffffffa027da60>] ? free_port_rcu+0x30/0x30 [openvswitch] [<ffffffff81539318>] __netif_receive_skb+0x1c8/0x620 [<ffffffff8153a4c0>] netif_receive_skb+0x80/0x90 [<ffffffff8115f14c>] ? ksize+0x1c/0xc0 [<ffffffff8153a610>] napi_skb_finish+0x50/0x70 [<ffffffff8153ac15>] napi_gro_receive+0xf5/0x140 [<ffffffffa00368ae>] vmxnet3_rq_rx_complete+0x51e/0x7c0 [vmxnet3] [<ffffffff8101ac90>] ? nommu_map_sg+0xe0/0xe0 [<ffffffffa0036da5>] vmxnet3_poll_rx_only+0x45/0xc0 [vmxnet3] [<ffffffff8153ae64>] net_rx_action+0x134/0x290 [<ffffffff8103db0d>] ? __ticket_spin_lock+0xd/0x30 [<ffffffff8106e1a8>] __do_softirq+0xa8/0x210 [<ffffffff8164596e>] ? _raw_spin_lock+0xe/0x20 [<ffffffff8164fd6c>] call_softirq+0x1c/0x30 [<ffffffff81016215>] do_softirq+0x65/0xa0 [<ffffffff8106e58e>] irq_exit+0x8e/0xb0 [<ffffffff81650633>] do_IRQ+0x63/0xe0 [<ffffffff81645e2e>] common_interrupt+0x6e/0x6e ----------- Bug #21853 Reported-by: Pawan Shukla <shuklap@vmware.com> Signed-off-by: Pravin B Shelar <pshelar@nicira.com> Acked-by: Jesse Gross <jesse@nicira.com>
Terrylol · Dec 16, 2013 · 9d73c9c · 9d73c9c
1 parent 4b6ab2b
commit 9d73c9c
Show file tree

Hide file tree

Showing 2 changed files with 32 additions and 22 deletions.
diff --git a/AUTHORS b/AUTHORS
@@ -209,6 +209,7 @@ Niklas Andersson        nandersson@nicira.com
 Padmanabhan Krishnan    kprad1@yahoo.com
 Pankaj Thakkar          thakkar@nicira.com
 Paulo Cravero           pcravero@as2594.net
+Pawan Shukla            shuklap@vmware.com
 Peter Balland           peter@nicira.com
 Peter Phaal             peter.phaal@inmon.com
 Prabina Pattnaik        Prabina.Pattnaik@nechclst.in

diff --git a/datapath/flow.c b/datapath/flow.c
@@ -87,17 +87,25 @@ void ovs_flow_stats_update(struct sw_flow *flow, struct sk_buff *skb)
 	spin_unlock(&stats->lock);
 }
 
-static void stats_read(struct flow_stats *stats,
+static void stats_read(struct flow_stats *stats, bool lock_bh,
 		       struct ovs_flow_stats *ovs_stats,
 		       unsigned long *used, __be16 *tcp_flags)
 {
-	spin_lock(&stats->lock);
+	if (lock_bh)
+		spin_lock_bh(&stats->lock);
+	else
+		spin_lock(&stats->lock);
+
 	if (time_after(stats->used, *used))
 		*used = stats->used;
 	*tcp_flags |= stats->tcp_flags;
 	ovs_stats->n_packets += stats->packet_count;
 	ovs_stats->n_bytes += stats->byte_count;
-	spin_unlock(&stats->lock);
+
+	if (lock_bh)
+		spin_unlock_bh(&stats->lock);
+	else
+		spin_unlock(&stats->lock);
 }
 
 void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
@@ -110,53 +118,54 @@ void ovs_flow_stats_get(struct sw_flow *flow, struct ovs_flow_stats *ovs_stats,
 	memset(ovs_stats, 0, sizeof(*ovs_stats));
 
 	if (!flow->stats.is_percpu) {
-		stats_read(flow->stats.stat, ovs_stats, used, tcp_flags);
+		stats_read(flow->stats.stat, true, 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();
+			bool lock_bh;
 
 			stats = per_cpu_ptr(flow->stats.cpu_stats, cpu);
-			stats_read(stats, ovs_stats, used, tcp_flags);
-
-			if (cpu == cur_cpu)
-				local_bh_enable();
+			lock_bh = (cpu == cur_cpu);
+			stats_read(stats, lock_bh, ovs_stats, used, tcp_flags);
 		}
 		put_cpu();
 	}
 }
 
-static void stats_reset(struct flow_stats *stats)
+static void stats_reset(struct flow_stats *stats, bool lock_bh)
 {
-	spin_lock(&stats->lock);
+	if (lock_bh)
+		spin_lock_bh(&stats->lock);
+	else
+		spin_lock(&stats->lock);
+
 	stats->used = 0;
 	stats->packet_count = 0;
 	stats->byte_count = 0;
 	stats->tcp_flags = 0;
-	spin_unlock(&stats->lock);
+
+	if (lock_bh)
+		spin_unlock_bh(&stats->lock);
+	else
+		spin_unlock(&stats->lock);
 }
 
 void ovs_flow_stats_clear(struct sw_flow *flow)
 {
 	int cpu, cur_cpu;
 
 	if (!flow->stats.is_percpu) {
-		stats_reset(flow->stats.stat);
+		stats_reset(flow->stats.stat, true);
 	} else {
 		cur_cpu = get_cpu();
 
 		for_each_possible_cpu(cpu) {
+			bool lock_bh;
 
-			if (cpu == cur_cpu)
-				local_bh_disable();
-
-			stats_reset(per_cpu_ptr(flow->stats.cpu_stats, cpu));
-
-			if (cpu == cur_cpu)
-				local_bh_enable();
+			lock_bh = (cpu == cur_cpu);
+			stats_reset(per_cpu_ptr(flow->stats.cpu_stats, cpu), lock_bh);
 		}
 		put_cpu();
 	}