Fix in script to avoid orchagent crash when port down followed by fdb…

[rupesh-k]

What I did
Observed that sometimes orchagent is hitting seg fault with below stack when port down followed by FDB delete.

Crash:
Thread 1 "orchagent" received signal SIGSEGV, Segmentation fault.
0x00007f8f742aebb3 in std::_Rb_tree_increment(std::_Rb_tree_node_base const*) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
(gdb) bt
#0 0x00007f8f742aebb3 in std::_Rb_tree_increment(std::_Rb_tree_node_base const*) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#1 0x000055c07f1f1078 in std::_Rb_tree_const_iterator::operator++ (this=) at /usr/include/c++/6/bits/stl_tree.h:288
#2 FdbOrch::update (this=this@entry=0x55c07f89f6d0, type=, entry=, bridge_port_id=) at fdborch.cpp:235
#3 0x000055c07f1f2002 in FdbOrch::doTask (this=0x55c07f89f6d0, consumer=...) at fdborch.cpp:485
#4 0x000055c07f15d712 in OrchDaemon::start (this=0x55c07f882e80) at orchdaemon.cpp:467
#5 0x000055c07f148322 in main (argc=, argv=) at main.cpp:346

Why I did it
Fixed in script to avoid this as it may be hitting some timing issue.

How I verified it
Ran script 50 times without any issue.

Details if related

[rupesh-k]

Hi @daall

Observed in swss-build-pr the tests failed, on further investigation found that it is hitting the crash in fdborch when port down is followed by fdb delete.

Fixing in script to avoid this.

I am not sure whom to follow up on the fdb orch crash.

Thanks

[daall]

retest this please

[daall]

Thanks for the quick find and fix @rupesh-k! Can you open an issue in the sonic-buildimage repo with the vs tag?

@lguohan FYI