Re: Problem with iotest 233

[Thomas Huth <thuth@redhat.com>]

On 25/02/2025 18.44, Thomas Huth wrote:
> On 25/02/2025 11.12, Kevin Wolf wrote:
>> Am 25.02.2025 um 08:20 hat Thomas Huth geschrieben:
>>>
>>>   Hi!
>>>
>>> I'm facing a weird hang in iotest 233 on my Fedora 41 laptop. When running
>>>
>>>   ./check -raw 233
>>>
>>> the test simply hangs. Looking at the log, the last message is "== check
>>> plain client to TLS server fails ==". I added some debug messages, and it
>>> seems like the previous NBD server is not correctly terminated here.
>>> The test works fine again if I apply this patch:
>>>
>>> diff --git a/tests/qemu-iotests/common.nbd b/tests/qemu-iotests/common.nbd
>>> --- a/tests/qemu-iotests/common.nbd
>>> +++ b/tests/qemu-iotests/common.nbd
>>> @@ -35,7 +35,7 @@ nbd_server_stop()
>>>           read NBD_PID < "$nbd_pid_file"
>>>           rm -f "$nbd_pid_file"
>>>           if [ -n "$NBD_PID" ]; then
>>> -            kill "$NBD_PID"
>>> +            kill -9 "$NBD_PID"
>>>           fi
>>>       fi
>>>       rm -f "$nbd_unix_socket" "$nbd_stderr_fifo"
>>>
>>> ... but that does not look like the right solution to me. What could prevent
>>> the qemu-nbd from correctly shutting down when it receives a normal SIGTERM
>>> signal?
>>
>> Not sure. In theory, qemu_system_killed() should set state = TERMINATE
>> and make main_loop_wait() return through the notification, which should
>> then make it shut down. Maybe you can attach gdb and check what 'state'
>> is when it hangs and if it's still in the main loop?
> 
> I attached a gdb and ran "bt", and it looks like it is hanging in an exit() 
> handler:
> 
> (gdb) bt
> #0  0x00007f127f8fff1d in syscall () from /lib64/libc.so.6
> #1  0x00007f127fd32e1d in g_cond_wait () from /lib64/libglib-2.0.so.0
> #2  0x00005583df3048b2 in flush_trace_file (wait=true) at ../../devel/qemu/ 
> trace/simple.c:140
> #3  st_flush_trace_buffer () at ../../devel/qemu/trace/simple.c:383
> #4  0x00007f127f8296c1 in __run_exit_handlers () from /lib64/libc.so.6
> #5  0x00007f127f82978e in exit () from /lib64/libc.so.6
> #6  0x00005583df1ae9e1 in main (argc=<optimized out>, argv=<optimized out>) 
> at ../../devel/qemu/qemu-nbd.c:1242

Ah, now that I wrote that: I recently ran "configure" with 
--enable-trace-backends=simple ... when I remove that from "config.status" 
again, then the test works fine again 8-)

Still, I think it should not hang with the simple trace backend here, should it?

  Thomas