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:
[ 58.543144] BUG: unable to handle kernel NULL pointer dereference at
0000000000000008
[ 58.545300] IP: perf_trace_tcp_retransmit_skb+0xd0/0x145
[ 58.546770] PGD 0 P4D 0
[ 58.547472] Oops: 0000 [#1] SMP
[ 58.548328] Modules linked in: vrf
[ 58.549262] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc4+ #26
[ 58.551004] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.7.5-20140531_083030-gandalf 04/01/2014
[ 58.554560] task: ffffffff81a0e540 task.stack: ffffffff81a00000
[ 58.555817] RIP: 0010:perf_trace_tcp_retransmit_skb+0xd0/0x145
[ 58.557137] RSP: 0018:ffff88003fc03d68 EFLAGS: 00010282
[ 58.558292] RAX: 0000000000000000 RBX: ffffe8ffffc0ec80 RCX: ffff880038543098
[ 58.559850] RDX: 0400000000000000 RSI: ffff88003fc03d70 RDI: ffff88003fc14b68
[ 58.561099] RBP: ffff88003fc03da8 R08: 0000000000000000 R09: ffffea0000d3224a
[ 58.562005] R10: ffff88003fc03db8 R11: 0000000000000010 R12: ffff8800385428c0
[ 58.562930] R13: ffffe8ffffc0e478 R14: ffffffff81a93a40 R15: ffff88003d4f0c00
[ 58.563845] FS: 0000000000000000(0000) GS:ffff88003fc00000(0000)
knlGS:0000000000000000
[ 58.564873] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 58.565613] CR2: 0000000000000008 CR3: 000000003d68f004 CR4: 00000000000606f0
[ 58.566538] Call Trace:
[ 58.566865] <IRQ>
[ 58.567140] __tcp_retransmit_skb+0x4ab/0x4c6
[ 58.567704] ? tcp_set_ca_state+0x22/0x3f
[ 58.568231] tcp_retransmit_skb+0x14/0xa3
[ 58.568754] tcp_retransmit_timer+0x472/0x5e3
[ 58.569324] ? tcp_write_timer_handler+0x1e9/0x1e9
[ 58.569946] tcp_write_timer_handler+0x95/0x1e9
[ 58.570548] tcp_write_timer+0x2a/0x58
Remove use of ipv6_pinfo in favor of data in sock_common.
Fixes: e086101b150a ("tcp: add a tracepoint for tcp retransmission")
Signed-off-by: David Ahern <dsah...@gmail.com>
---
v3
- remove use of inet6_sk and check sk_family (requested by Eric)
- Add IS_ENABLED(CONFIG_IPV6) around use of sk_v6_rcv_saddr and
sk_v6_daddr as done in sock_common (noted by Cong)
v2
- remove np and get addresses from sock_common
include/trace/events/tcp.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 3d1cbd072b7e..271812216ce3 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -27,7 +27,6 @@ TRACE_EVENT(tcp_retransmit_skb,
),
TP_fast_assign(
- struct ipv6_pinfo *np = inet6_sk(sk);
struct inet_sock *inet = inet_sk(sk);
struct in6_addr *pin6;
__be32 *p32;
@@ -44,12 +43,15 @@ TRACE_EVENT(tcp_retransmit_skb,
p32 = (__be32 *) __entry->daddr;
*p32 = inet->inet_daddr;
- if (np) {
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == AF_INET6) {
pin6 = (struct in6_addr *)__entry->saddr_v6;
- *pin6 = np->saddr;
+ *pin6 = sk->sk_v6_rcv_saddr;
pin6 = (struct in6_addr *)__entry->daddr_v6;
- *pin6 = *(np->daddr_cache);
- } else {
+ *pin6 = sk->sk_v6_daddr;
+ } else
+#endif
+ {
pin6 = (struct in6_addr *)__entry->saddr_v6;
ipv6_addr_set_v4mapped(inet->inet_saddr, pin6);
pin6 = (struct in6_addr *)__entry->daddr_v6;
--
2.1.4
