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Message-Id: <1439923216-25295-1-git-send-email-razor@blackwall.org>
Date: Tue, 18 Aug 2015 21:40:16 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: netdev@...r.kernel.org
Cc: dsa@...ulusnetworks.com, shm@...ulusnetworks.com,
davem@...emloft.net,
Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Subject: [PATCH net-next v3] vrf: vrf_master_ifindex_rcu is not always called with rcu read lock
From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
While running net-next I hit this:
[ 634.073119] ===============================
[ 634.073150] [ INFO: suspicious RCU usage. ]
[ 634.073182] 4.2.0-rc6+ #45 Not tainted
[ 634.073213] -------------------------------
[ 634.073244] include/net/vrf.h:38 suspicious rcu_dereference_check()
usage!
[ 634.073274]
other info that might help us debug this:
[ 634.073307]
rcu_scheduler_active = 1, debug_locks = 1
[ 634.073338] 2 locks held by swapper/0/0:
[ 634.073369] #0: (((&n->timer))){+.-...}, at: [<ffffffff8112bc35>]
call_timer_fn+0x5/0x480
[ 634.073412] #1: (slock-AF_INET){+.-...}, at: [<ffffffff8174f0f5>]
icmp_send+0x155/0x5f0
[ 634.073450]
stack backtrace:
[ 634.073483] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-rc6+ #45
[ 634.073514] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[ 634.073545] 0000000000000000 0593ba8242d9ace4 ffff88002fc03b48
ffffffff81803f1b
[ 634.073612] 0000000000000000 ffffffff81e12500 ffff88002fc03b78
ffffffff811003c5
[ 634.073642] 0000000000000000 ffff88002ec4e600 ffffffff81f00f80
ffff88002fc03cf0
[ 634.073669] Call Trace:
[ 634.073694] <IRQ> [<ffffffff81803f1b>] dump_stack+0x4c/0x65
[ 634.073728] [<ffffffff811003c5>] lockdep_rcu_suspicious+0xc5/0x100
[ 634.073763] [<ffffffff8174eb56>] icmp_route_lookup+0x176/0x5c0
[ 634.073793] [<ffffffff8174f2fb>] ? icmp_send+0x35b/0x5f0
[ 634.073818] [<ffffffff8174f274>] ? icmp_send+0x2d4/0x5f0
[ 634.073844] [<ffffffff8174f3ce>] icmp_send+0x42e/0x5f0
[ 634.073873] [<ffffffff8170b662>] ipv4_link_failure+0x22/0xa0
[ 634.073899] [<ffffffff8174bdda>] arp_error_report+0x3a/0x80
[ 634.073926] [<ffffffff816d6100>] ? neigh_lookup+0x2c0/0x2c0
[ 634.073952] [<ffffffff816d396e>] neigh_invalidate+0x8e/0x110
[ 634.073984] [<ffffffff816d62ae>] neigh_timer_handler+0x1ae/0x290
[ 634.074013] [<ffffffff816d6100>] ? neigh_lookup+0x2c0/0x2c0
[ 634.074013] [<ffffffff8112bce3>] call_timer_fn+0xb3/0x480
[ 634.074013] [<ffffffff8112bc35>] ? call_timer_fn+0x5/0x480
[ 634.074013] [<ffffffff816d6100>] ? neigh_lookup+0x2c0/0x2c0
[ 634.074013] [<ffffffff8112c2bc>] run_timer_softirq+0x20c/0x430
[ 634.074013] [<ffffffff810af50e>] __do_softirq+0xde/0x630
[ 634.074013] [<ffffffff810afc97>] irq_exit+0x117/0x120
[ 634.074013] [<ffffffff81810976>] smp_apic_timer_interrupt+0x46/0x60
[ 634.074013] [<ffffffff8180e950>] apic_timer_interrupt+0x70/0x80
[ 634.074013] <EOI> [<ffffffff8106b9d6>] ? native_safe_halt+0x6/0x10
[ 634.074013] [<ffffffff81101d8d>] ? trace_hardirqs_on+0xd/0x10
[ 634.074013] [<ffffffff81027d43>] default_idle+0x23/0x200
[ 634.074013] [<ffffffff8102852f>] arch_cpu_idle+0xf/0x20
[ 634.074013] [<ffffffff810f89ba>] default_idle_call+0x2a/0x40
[ 634.074013] [<ffffffff810f8dcc>] cpu_startup_entry+0x39c/0x4c0
[ 634.074013] [<ffffffff817f9cad>] rest_init+0x13d/0x150
[ 634.074013] [<ffffffff81f69038>] start_kernel+0x4a8/0x4c9
[ 634.074013] [<ffffffff81f68120>] ?
early_idt_handler_array+0x120/0x120
[ 634.074013] [<ffffffff81f68339>] x86_64_start_reservations+0x2a/0x2c
[ 634.074013] [<ffffffff81f68485>] x86_64_start_kernel+0x14a/0x16d
It would seem vrf_master_ifindex_rcu() can be called without RCU held in
other contexts as well so introduce a new helper which acquires rcu and
returns the ifindex.
Also add curly braces around both the "if" and "else" parts as per the
style guide.
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
---
v3: keep the rcu comment above vrf_master_ifindex_rcu()
v2: use a new helper that acquires and releases rcu instead
include/net/vrf.h | 20 ++++++++++++++++++--
net/ipv4/icmp.c | 4 ++--
2 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/include/net/vrf.h b/include/net/vrf.h
index 3bb4af462ed6..5bfb16237fd7 100644
--- a/include/net/vrf.h
+++ b/include/net/vrf.h
@@ -43,9 +43,9 @@ static inline int vrf_master_ifindex_rcu(const struct net_device *dev)
if (!dev)
return 0;
- if (netif_is_vrf(dev))
+ if (netif_is_vrf(dev)) {
ifindex = dev->ifindex;
- else {
+ } else {
vrf_ptr = rcu_dereference(dev->vrf_ptr);
if (vrf_ptr)
ifindex = vrf_ptr->ifindex;
@@ -54,6 +54,17 @@ static inline int vrf_master_ifindex_rcu(const struct net_device *dev)
return ifindex;
}
+static inline int vrf_master_ifindex(const struct net_device *dev)
+{
+ int ifindex;
+
+ rcu_read_lock();
+ ifindex = vrf_master_ifindex_rcu(dev);
+ rcu_read_unlock();
+
+ return ifindex;
+}
+
/* called with rcu_read_lock */
static inline int vrf_dev_table_rcu(const struct net_device *dev)
{
@@ -133,6 +144,11 @@ static inline int vrf_master_ifindex_rcu(const struct net_device *dev)
return 0;
}
+static inline int vrf_master_ifindex(const struct net_device *dev)
+{
+ return 0;
+}
+
static inline int vrf_dev_table_rcu(const struct net_device *dev)
{
return 0;
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index c6f1ce149ffb..f16488efa1c8 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -426,7 +426,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
fl4.flowi4_mark = mark;
fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
fl4.flowi4_proto = IPPROTO_ICMP;
- fl4.flowi4_oif = vrf_master_ifindex_rcu(skb->dev) ? : skb->dev->ifindex;
+ fl4.flowi4_oif = vrf_master_ifindex(skb->dev) ? : skb->dev->ifindex;
security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
rt = ip_route_output_key(net, &fl4);
if (IS_ERR(rt))
@@ -460,7 +460,7 @@ static struct rtable *icmp_route_lookup(struct net *net,
fl4->flowi4_proto = IPPROTO_ICMP;
fl4->fl4_icmp_type = type;
fl4->fl4_icmp_code = code;
- fl4->flowi4_oif = vrf_master_ifindex_rcu(skb_in->dev) ? : skb_in->dev->ifindex;
+ fl4->flowi4_oif = vrf_master_ifindex(skb_in->dev) ? : skb_in->dev->ifindex;
security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
rt = __ip_route_output_key(net, fl4);
--
2.4.3
--
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