[ws] BUS FAULT occurs when connect and disconnect websocket server for several times.

[qiaojingx]

Description

Try to connect and disconnect with websocket server for several times, BUS FAULT error will happen.

Test Code

WebSocketServer.js;

Steps to Reproduction

1. make JS=samples/websockets/WebSocketServer.js BOARD=frdm_k64f
2. cp outdir/frdm_k64f/zephyr.bin /media/<username>/MBED/
3. node samples/websockets/NodeWebSocketClient.js
4. CTRL+C to disconnect
5. repeat steps 3 and 4(error happens after about 5 times).

Actual Result

Expected Result

No error occurs.

Test Builds

Branch	Commit Id	Target Device	Test Date	Result
master	dcf56a9	FRDM-K64F	Nov 20, 2017	Fail

Additional Information

[jimmy-huang]

@qiaojingx Is this reproducible with master, it seemed the original check was with Zephyr 1.9, but I can't reproduce this on Zephyr 1.10. However, I do get ip route dropped on the linux time periodically, and I have to add route again.

[qiaojingx]

Verifed with commit 4b23a47. This issue happens with a much lower reappearance rate now(disconnect for 10+times).

And if keep connection from the beginning, issue #1725 will occurs.

[jimmy-huang]

@brianjjones and @jprestwo were able to reproduce this yesterday and root-caused this bug, so a patch is on the way, don't close this until that's in.

[qiaojingx]

Verified with commit 0c0af9b, not reproduced.