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Re: [Qemu-devel] tpm-tis-test and tpm-crb-test crash on OSX


From: Stefan Berger
Subject: Re: [Qemu-devel] tpm-tis-test and tpm-crb-test crash on OSX
Date: Fri, 16 Mar 2018 10:08:01 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0

On 03/16/2018 09:45 AM, Stefan Berger wrote:
On 03/16/2018 09:41 AM, Marc-André Lureau wrote:
Hi

On Fri, Mar 16, 2018 at 2:37 PM, Marc-André Lureau
<address@hidden> wrote:
Hi

On Fri, Mar 16, 2018 at 2:27 PM, Daniel P. Berrangé <address@hidden> wrote:
On Fri, Mar 16, 2018 at 01:24:53PM +0000, Peter Maydell wrote:
On 16 March 2018 at 13:12, Peter Maydell <address@hidden> wrote:
On OSX host, I noticed that tpm-tis-test and tpm-crb-test
both crash on OSX, hitting an error_abort case:

(lldb) run
Process 65115 launched:
'/Users/pm215/src/qemu-for-merges/build/all/tests/tpm-tis-test'
(x86_64)
/i386/tpm-tis/test_check_localities: OK
/i386/tpm-tis/test_check_access_reg: OK
/i386/tpm-tis/test_check_access_reg_seize: OK
/i386/tpm-tis/test_check_access_reg_release: OK
/i386/tpm-tis/test_check_transmit: OK
Unexpected error in qio_channel_socket_readv() at
/Users/pm215/src/qemu-for-merges/io/channel-socket.c:494:
Unable to read from socket: Bad file descriptor

Here's a backtrace from tpm-tis-test:
Dan suggested a race condition, which prompted me to get an
all-threads backtrace:

   thread #1: tid = 0xb50f19, 0x00007fff7eb97502
libsystem_kernel.dylib`__wait4 + 10, queue = 'com.apple.main-thread'
     frame #0: 0x00007fff7eb97502 libsystem_kernel.dylib`__wait4 + 10
     frame #1: 0x000000010001b303 tpm-tis-test`qtest_quit [inlined]
kill_qemu(s=<unavailable>) + 99 at libqtest.c:107
     frame #2: 0x000000010001b2df
tpm-tis-test`qtest_quit(s=0x0000000100404c60) + 63 at libqtest.c:280
frame #3: 0x0000000100001bd1 tpm-tis-test`main [inlined] qtest_end
+ 9 at libqtest.h:555
frame #4: 0x0000000100001bc8 tpm-tis-test`main(argc=<unavailable>,
argv=<unavailable>) + 520 at tpm-tis-test.c:477
     frame #5: 0x00007fff7ea47115 libdyld.dylib`start + 1
     frame #6: 0x00007fff7ea47115 libdyld.dylib`start + 1

   thread #3: tid = 0xb50f4a, 0x00007fff7eb977d2
libsystem_kernel.dylib`close + 10
     frame #0: 0x00007fff7eb977d2 libsystem_kernel.dylib`close + 10
     frame #1: 0x0000000100007def
tpm-tis-test`qio_channel_socket_close(ioc=<unavailable>,
errp=0x000000010006c930) + 63 at channel-socket.c:693
     frame #2: 0x00000001000039f9
tpm-tis-test`tpm_emu_ctrl_thread(data=0x00007ffeefbff0e8) + 713 at
tpm-emu.c:128
frame #3: 0x00000001001b2ec0 libglib-2.0.0.dylib`g_thread_create_proxy + 191 frame #4: 0x00007fff7ecd26c1 libsystem_pthread.dylib`_pthread_body + 340 frame #5: 0x00007fff7ecd256d libsystem_pthread.dylib`_pthread_start + 377 frame #6: 0x00007fff7ecd1c5d libsystem_pthread.dylib`thread_start + 13

* thread #2: tid = 0xb50f50, 0x00007fff7eb96e3e
libsystem_kernel.dylib`__pthread_kill + 10
* frame #0: 0x00007fff7eb96e3e libsystem_kernel.dylib`__pthread_kill + 10 frame #1: 0x00007fff7ecd5150 libsystem_pthread.dylib`pthread_kill + 333
     frame #2: 0x00007fff7eaf3312 libsystem_c.dylib`abort + 127
     frame #3: 0x0000000100043431 tpm-tis-test`error_setv [inlined]
error_handle_fatal(errp=<unavailable>) + 43 at error.c:38
     frame #4: 0x0000000100043406
tpm-tis-test`error_setv(errp=<unavailable>, src=<unavailable>,
line=<unavailable>, func=<unavailable>,
err_class=ERROR_CLASS_GENERIC_ERROR, fmt=<unavailable>,
ap=<unavailable>, suffix=<unavailable>) + 246 at error.c:71
     frame #5: 0x00000001000435db
tpm-tis-test`error_setg_errno_internal(errp=0x000000010006c930,
src="/Users/pm215/src/qemu-for-merges/io/channel-socket.c", line=494,
func="qio_channel_socket_readv", os_errno=<unavailable>, fmt="Unable
to read from socket") + 219 at error.c:111
     frame #6: 0x0000000100007ba5
tpm-tis-test`qio_channel_socket_readv(ioc=<unavailable>,
iov=<unavailable>, niov=<unavailable>, fds=0x0000000000000000,
nfds=0x0000000000000000, errp=0x000000010006c930) + 341 at
channel-socket.c:493
     frame #7: 0x0000000100004717 tpm-tis-test`qio_channel_read
[inlined] qio_channel_readv_full(ioc=0x00000001007006b0,
iov=<unavailable>, niov=1, fds=<unavailable>, nfds=<unavailable>,
errp=0x000000010006c930) + 62 at channel.c:65
     frame #8: 0x00000001000046d9
tpm-tis-test`qio_channel_read(ioc=0x00000001007006b0,
buf=<unavailable>, buflen=<unavailable>, errp=<unavailable>) + 41 at
channel.c:216
     frame #9: 0x0000000100003dd1
tpm-tis-test`tpm_emu_tpm_thread(data=0x00007ffeefbff0e8) + 241 at
tpm-emu.c:41
     frame #10: 0x00000001001b2ec0
libglib-2.0.0.dylib`g_thread_create_proxy + 191
frame #11: 0x00007fff7ecd26c1 libsystem_pthread.dylib`_pthread_body + 340 frame #12: 0x00007fff7ecd256d libsystem_pthread.dylib`_pthread_start + 377 frame #13: 0x00007fff7ecd1c5d libsystem_pthread.dylib`thread_start + 13


My guess is that the problem here is that the tpm_emu_ctrl_thread (thread 3) is forcibly closing the channel, which causes the tpm_emu_thread (thread 2)
to abort because its read returned an error.
At least the tpm_emu_tpm_thread() there is only something in the test
suite, so the real system emulator code isn't at risk of crashing.

Feels like the thread simply should *not* use error_abort, and instead
have a more graceful way to exit when the socket closes

The code expects the read() to return 0 on disconnect, not an error.
Apparently this works on !osx. Should we adapt qio-channel-socket to
return 0 in this case on osx too?
Oh I see, it calls close() on the same end, that's not correct. I
wonder if shutdown would be better. Other suggestions?

We could send the thread a special message, like 0xff ff ff ff, and that terminates it...

... wrong end of socket, so doesn't work. Other way would be to pass a pipe to the TPM emulator thread and have it poll on the pipefd and the channelfd and terminate upon pipefd reception...



    Stefan






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