On Tue, Jan 31, 2017 at 7:44 AM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> On Mon, 2017-01-30 at 22:19 -0800, Cong Wang wrote:
>
>>
>> The context is process context (TX path before hitting qdisc), and
>> BH is not disabled, so in_interrupt() doesn't catch it. Hmm, this
>> makes me thinking maybe we really need to disable BH in this
>> case for nf_hook()? But it is called in RX path too, and BH is
>> already disabled there.
>
> ipt_do_table() and similar netfilter entry points disable BH.
>
> Maybe it is done too late.
I think we need a fix like the following one for minimum impact.
diff --git a/net/core/dev.c b/net/core/dev.c
index 727b6fd..eee7d63 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1720,12 +1720,10 @@ EXPORT_SYMBOL(net_enable_timestamp);
void net_disable_timestamp(void)
{
#ifdef HAVE_JUMP_LABEL
- if (in_interrupt()) {
- atomic_inc(&netstamp_needed_deferred);
- return;
- }
-#endif
+ atomic_inc(&netstamp_needed_deferred);
+#else
static_key_slow_dec(&netstamp_needed);
+#endif
}
EXPORT_SYMBOL(net_disable_timestamp);
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