On Wed, Jan 04, 2017 at 09:32:01AM +0800, zhanghailiang wrote:
> From: Caoxinhua <caoxin...@huawei.com>
>
> QEMU will crash with the follow backtrace if the new created thread exited
> before
> we call qemu_thread_set_name() for it.
>
> (gdb) bt
> #0 0x00007f9a68b095d7 in __GI_raise (sig=sig@entry=6) at
> ../nptl/sysdeps/unix/sysv/linux/raise.c:56
> #1 0x00007f9a68b0acc8 in __GI_abort () at abort.c:90
> #2 0x00007f9a69cda389 in PAT_abort () from /usr/lib64/libuvpuserhotfix.so
> #3 0x00007f9a69cdda0d in patchIllInsHandler () from
> /usr/lib64/libuvpuserhotfix.so
> #4 <signal handler called>
> #5 pthread_setname_np (th=140298470549248, name=name@entry=0x8cc74a
> "io-task-worker") at ../nptl/sysdeps/unix/sysv/linux/pthread_setname.c:49
> #6 0x00000000007f5f20 in qemu_thread_set_name
> (thread=thread@entry=0x7ffd2ac09680, name=name@entry=0x8cc74a
> "io-task-worker") at util/qemu_thread_posix.c:459
> #7 0x00000000007f679e in qemu_thread_create
> (thread=thread@entry=0x7ffd2ac09680, name=name@entry=0x8cc74a
> "io-task-worker",start_routine=start_routine@entry=0x7c1300
> <qio_task_thread_worker>, arg=arg@entry=0x7f99b8001720, mode=mode@entry=1) at
> util/qemu_thread_posix.c:498
> #8 0x00000000007c15b6 in qio_task_run_in_thread
> (task=task@entry=0x7f99b80033d0, worker=worker@entry=0x7bd920
> <qio_channel_socket_connect_worker>, opaque=0x7f99b8003370, destroy=0x7c6220
> <qapi_free_SocketAddress>) at io/task.c:133
> #9 0x00000000007bda04 in qio_channel_socket_connect_async
> (ioc=0x7f99b80014c0, addr=0x37235d0, callback=callback@entry=0x54ad00
> <qemu_chr_socket_connected>, opaque=opaque@entry=0x38118b0,
> destroy=destroy@entry=0x0) at io/channel_socket.c:191
> #10 0x00000000005487f6 in socket_reconnect_timeout (opaque=0x38118b0) at
> qemu_char.c:4402
> #11 0x00007f9a6a1533b3 in g_timeout_dispatch () from
> /usr/lib64/libglib-2.0.so.0
> #12 0x00007f9a6a15299a in g_main_context_dispatch () from
> /usr/lib64/libglib-2.0.so.0
> #13 0x0000000000747386 in glib_pollfds_poll () at main_loop.c:227
> #14 0x0000000000747424 in os_host_main_loop_wait (timeout=404000000) at
> main_loop.c:272
> #15 0x0000000000747575 in main_loop_wait (nonblocking=nonblocking@entry=0)
> at main_loop.c:520
> #16 0x0000000000557d31 in main_loop () at vl.c:2170
> #17 0x000000000041c8b7 in main (argc=<optimized out>, argv=<optimized out>,
> envp=<optimized out>) at vl.c:5083
>
> Let's detach the new thread after calling qemu_thread_set_name().
>
> Signed-off-by: Caoxinhua <caoxin...@huawei.com>
> ---
> v2:
> Fix missing title
> ---
> util/qemu-thread-posix.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
> index d20cdde..d31793d 100644
> --- a/util/qemu-thread-posix.c
> +++ b/util/qemu-thread-posix.c
> @@ -481,12 +481,6 @@ void qemu_thread_create(QemuThread *thread, const char
> *name,
> if (err) {
> error_exit(err, __func__);
> }
> - if (mode == QEMU_THREAD_DETACHED) {
> - err = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
> - if (err) {
> - error_exit(err, __func__);
> - }
> - }
>
> /* Leave signal handling to the iothread. */
> sigfillset(&set);
> @@ -499,6 +493,12 @@ void qemu_thread_create(QemuThread *thread, const char
> *name,
> qemu_thread_set_name(thread, name);
> }
>
> + if (mode == QEMU_THREAD_DETACHED) {
> + err = pthread_detach(thread->thread);
> + if (err) {
> + error_exit(err, __func__);
> + }
> + }
Is it permitted to be calling pthread_detach(), if there is a chance that
the thread has already exited ? It seems reasonable, since a non-detached
thread shouldl remain in a zombie state waiting to be join'd, but the man
page is unclear on behaviour.
Regards,
Daniel
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