Re: [PATCH v2 net-next] tcp: Check daddr_cache before use in tracepoint

From: David Ahern <redacted>
Date: Mon, 16 Oct 2017 15:32:07 -0700

Running perf in one window to capture tcp_retransmit_skb tracepoint:
    $ perf record -e tcp:tcp_retransmit_skb -a

And causing a retransmission on an active TCP session (e.g., dropping
packets in the receiver, changing MTU on the interface to 500 and back
to 1500) triggers a panic:

 ...

Check that daddr_cache is non-NULL before de-referencing.

Fixes: e086101b150a ("tcp: add a tracepoint for tcp retransmission")
Signed-off-by: David Ahern <redacted>

Applied.