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Message-ID: <1322515010.2970.24.camel@edumazet-laptop>
Date: Mon, 28 Nov 2011 22:16:50 +0100
From: Eric Dumazet <eric.dumazet@...il.com>
To: igorm@....rs
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH 1/1] netstamp_needed shouldn't be jump_label_key
Le lundi 28 novembre 2011 à 21:33 +0100, Eric Dumazet a écrit :
> Le lundi 28 novembre 2011 à 21:23 +0100, igorm@....rs a écrit :
> > From: Igor Maravic <igorm@....rs>
> >
> > Problem with setting netstamp_needed as jump_label_key is that
> > it inc/dec, functions net_enable_timestamp/net_disable_timestamp,
> > are called from interrupts.
> >
> > That can cause DEADLOCK, because jump_label_{inc, dec} are using mutex locking,
> > that may sleep.
> >
> > Signed-off-by: Igor Maravic <igorm@....rs>
> >
>
> Come on, we can find another way to handle this :)
>
> Its net-next, we are allowed to try to find something better.
>
Could you test following patch ?
Thanks
[PATCH net-next] net: dont call jump_label_dec from irq context
Igor Maravic reported an error caused by jump_label_dec() being called
from IRQ context :
BUG: sleeping function called from invalid context at kernel/mutex.c:271
in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper
1 lock held by swapper/0:
#0: (&n->timer){+.-...}, at: [<ffffffff8107ce90>] call_timer_fn+0x0/0x340
Pid: 0, comm: swapper Not tainted 3.2.0-rc2-net-next-mpls+ #1
Call Trace:
<IRQ> [<ffffffff8104f417>] __might_sleep+0x137/0x1f0
[<ffffffff816b9a2f>] mutex_lock_nested+0x2f/0x370
[<ffffffff810a89fd>] ? trace_hardirqs_off+0xd/0x10
[<ffffffff8109a37f>] ? local_clock+0x6f/0x80
[<ffffffff810a90a5>] ? lock_release_holdtime.part.22+0x15/0x1a0
[<ffffffff81557929>] ? sock_def_write_space+0x59/0x160
[<ffffffff815e936e>] ? arp_error_report+0x3e/0x90
[<ffffffff810969cd>] atomic_dec_and_mutex_lock+0x5d/0x80
[<ffffffff8112fc1d>] jump_label_dec+0x1d/0x50
[<ffffffff81566525>] net_disable_timestamp+0x15/0x20
[<ffffffff81557a75>] sock_disable_timestamp+0x45/0x50
[<ffffffff81557b00>] __sk_free+0x80/0x200
[<ffffffff815578d0>] ? sk_send_sigurg+0x70/0x70
[<ffffffff815e936e>] ? arp_error_report+0x3e/0x90
[<ffffffff81557cba>] sock_wfree+0x3a/0x70
[<ffffffff8155c2b0>] skb_release_head_state+0x70/0x120
[<ffffffff8155c0b6>] __kfree_skb+0x16/0x30
[<ffffffff8155c119>] kfree_skb+0x49/0x170
[<ffffffff815e936e>] arp_error_report+0x3e/0x90
[<ffffffff81575bd9>] neigh_invalidate+0x89/0xc0
[<ffffffff81578dbe>] neigh_timer_handler+0x9e/0x2a0
[<ffffffff81578d20>] ? neigh_update+0x640/0x640
[<ffffffff81073558>] __do_softirq+0xc8/0x3a0
Since jump_label_{inc|dec} must be called from process context only,
we must defer jump_label_dec() if net_disable_timestamp() is called
from interrupt context.
Reported-by: Igor Maravic <igorm@....rs>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/core/dev.c | 23 +++++++++++++++++++++++
net/ipv4/netfilter/ip_queue.c | 6 ++++--
net/ipv6/netfilter/ip6_queue.c | 5 ++++-
3 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 8afb244..de5266c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1443,15 +1443,38 @@ int call_netdevice_notifiers(unsigned long val, struct net_device *dev)
EXPORT_SYMBOL(call_netdevice_notifiers);
static struct jump_label_key netstamp_needed __read_mostly;
+#ifdef HAVE_JUMP_LABEL
+/* We are not allowed to call jump_label_dec() from irq context
+ * If net_disable_timestamp() is called from irq context, defer the
+ * jump_label_dec() calls.
+ */
+static atomic_t netstamp_needed_deferred;
+#endif
void net_enable_timestamp(void)
{
+#ifdef HAVE_JUMP_LABEL
+ int deferred = atomic_xchg(&netstamp_needed_deferred, 0);
+
+ if (deferred) {
+ while (--deferred)
+ jump_label_dec(&netstamp_needed);
+ return;
+ }
+#endif
+ WARN_ON(in_interrupt());
jump_label_inc(&netstamp_needed);
}
EXPORT_SYMBOL(net_enable_timestamp);
void net_disable_timestamp(void)
{
+#ifdef HAVE_JUMP_LABEL
+ if (in_interrupt()) {
+ atomic_inc(&netstamp_needed_deferred);
+ return;
+ }
+#endif
jump_label_dec(&netstamp_needed);
}
EXPORT_SYMBOL(net_disable_timestamp);
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c
index e59aabd..a057fe6 100644
--- a/net/ipv4/netfilter/ip_queue.c
+++ b/net/ipv4/netfilter/ip_queue.c
@@ -404,6 +404,7 @@ __ipq_rcv_skb(struct sk_buff *skb)
int status, type, pid, flags;
unsigned int nlmsglen, skblen;
struct nlmsghdr *nlh;
+ bool enable_timestamp = false;
skblen = skb->len;
if (skblen < sizeof(*nlh))
@@ -441,12 +442,13 @@ __ipq_rcv_skb(struct sk_buff *skb)
RCV_SKB_FAIL(-EBUSY);
}
} else {
- net_enable_timestamp();
+ enable_timestamp = true;
peer_pid = pid;
}
spin_unlock_bh(&queue_lock);
-
+ if (enable_timestamp)
+ net_enable_timestamp();
status = ipq_receive_peer(NLMSG_DATA(nlh), type,
nlmsglen - NLMSG_LENGTH(0));
if (status < 0)
diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c
index e63c397..fb80a23 100644
--- a/net/ipv6/netfilter/ip6_queue.c
+++ b/net/ipv6/netfilter/ip6_queue.c
@@ -405,6 +405,7 @@ __ipq_rcv_skb(struct sk_buff *skb)
int status, type, pid, flags;
unsigned int nlmsglen, skblen;
struct nlmsghdr *nlh;
+ bool enable_timestamp = false;
skblen = skb->len;
if (skblen < sizeof(*nlh))
@@ -442,11 +443,13 @@ __ipq_rcv_skb(struct sk_buff *skb)
RCV_SKB_FAIL(-EBUSY);
}
} else {
- net_enable_timestamp();
+ enable_timestamp = true;
peer_pid = pid;
}
spin_unlock_bh(&queue_lock);
+ if (enable_timestamp)
+ net_enable_timestamp();
status = ipq_receive_peer(NLMSG_DATA(nlh), type,
nlmsglen - NLMSG_LENGTH(0));
--
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