Make sure that vm = vlib_mains [thread_index], not vm = vlib_mains[0] =
&vlib_global_main.
>From what you wrote, I suspect that’s the problem.
D.
From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of PRANAB DAS
Sent: Friday, February 5, 2021 7:38 PM
To: vpp-dev@lists.fd.io
Subject: [vpp-dev] vlib_put_frame_to_node to udp-encap causes main-thread crash
Hi
I am puzzled by the crash in the main-thread caused by the following code
snippet that I have used to send control message payload over a udp encap
tunnel. The udp encap tunnel is created using udp encap vppcli. The code below
works when only a few packets are sent. But when I tried to send a burst of
these messages, for instance in a for loop with count 10 it causes a crash on
the main-thread even though the call is made on a worker thread.
Really appreciate it you could provide some information how to debug this.
Thank you
if (vlib_buffer_alloc (vm, &bi0, 1) != 1)
{
return -1;
}
b0 = vlib_get_buffer (vm, bi0);
udp4_encap_node = vlib_get_node_by_name(vm, (u8 *) "udp4-encap");
dp4_encap_node_index=udp4_encap_node->index;
vnet_buffer(b0)->sw_if_index[VLIB_RX] = 0;
vnet_buffer(b0)->ip.adj_index[VLIB_TX] = 0; // udp encap tunnel created with
index 0
vlib_frame_t *f = vlib_get_frame_to_node(vm, udp4_encap_node_index);
u32 *to_next = vlib_frame_vector_args(f);
to_next[0] = bi0;
f->n_vectors = 1;
vlib_put_frame_to_node(vm, udp4_encap_node_index, f);
This is the back trace. I don't understand how vlib_put_frame_to_node on a
worker thread can trigger a crash on the main thread. Is it caused by some
corruption ?
Thread 1 "vpp_main" received signal SIGSEGV, Segmentation fault.
dispatch_pending_node (vm=vm@entry=0x7f55e8b94300 <vlib_global_main>,
pending_frame_index=pending_frame_index@entry=3,
last_time_stamp=510933815354328)
at /usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/main.c:1500
1500 nf->flags |= VLIB_FRAME_IS_ALLOCATED;
(gdb) bt
#0 dispatch_pending_node (vm=vm@entry=0x7f55e8b94300 <vlib_global_main>,
pending_frame_index=pending_frame_index@entry=3,
last_time_stamp=510933815354328)
at /usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/main.c:1500
#1 0x00007f55e8938bf6 in vlib_main_or_worker_loop (is_main=1,
vm=0x7f55e8b94300 <vlib_global_main>)
at /usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/main.c:2013
#2 vlib_main_loop (vm=0x7f55e8b94300 <vlib_global_main>) at
/usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/main.c:2141
#3 vlib_main (vm=<optimized out>, vm@entry=0x7f55e8b94300 <vlib_global_main>,
input=input@entry=0x7f55a7fd6fa0)
at /usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/main.c:2387
#4 0x00007f55e8978c46 in thread0 (arg=140006953403136) at
/usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/unix/main.c:673
#5 0x00007f55e80243dc in clib_calljmp () from /lib64/libvppinfra.so.20.05.1
#6 0x00007ffd742d0920 in ?? ()
#7 0x00007f55e8979ced in vlib_unix_main (argc=<optimized out>, argv=<optimized
out>)
at
/usr/src/debug/vpp-20.05.1-2~gcb5420544_dirty.x86_64/src/vlib/unix/main.c:745
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