Re: [Qemu-devel] [PATCH v4 06/10] iohandler: switch to GPollFD

[Jan Kiszka]

On 2013-02-20 11:28, Stefan Hajnoczi wrote:
> Convert iohandler_select_fill() and iohandler_select_poll() to use
> GPollFD instead of rfds/wfds/xfds.

Since this commmit, I'm getting QEMU lock-ups, apparently slirp is
involved (the Linux guest tries to start its network at this point):

(gdb) thread apply all bt

Thread 3 (Thread 0x7fffed0e3700 (LWP 26788)):
#0  __lll_lock_wait () at 
../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:136
#1  0x00007ffff44c7294 in _L_lock_999 () from /lib64/libpthread.so.0
#2  0x00007ffff44c70aa in __pthread_mutex_lock (mutex=0x5555560afcc0) at 
pthread_mutex_lock.c:61
#3  0x00005555558945e9 in qemu_mutex_lock (mutex=<value optimized out>) at 
/data/qemu/util/qemu-thread-posix.c:57
#4  0x00005555557d9da5 in kvm_cpu_exec (env=0x55555689c9f0) at 
/data/qemu/kvm-all.c:1564
#5  0x0000555555780091 in qemu_kvm_cpu_thread_fn (arg=0x55555689c9f0) at 
/data/qemu/cpus.c:759
#6  0x00007ffff44c4a3f in start_thread (arg=0x7fffed0e3700) at 
pthread_create.c:297
#7  0x00007ffff2fb871d in clone () at 
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#8  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7fffed8e4700 (LWP 26787)):
#0  sem_timedwait () at 
../nptl/sysdeps/unix/sysv/linux/x86_64/sem_timedwait.S:103
#1  0x0000555555894a93 in qemu_sem_timedwait (sem=0x555556090020, ms=<value 
optimized out>) at /data/qemu/util/qemu-thread-posix.c:237
#2  0x000055555575116e in worker_thread (unused=<value optimized out>) at 
/data/qemu/thread-pool.c:88
#3  0x00007ffff44c4a3f in start_thread (arg=0x7fffed8e4700) at 
pthread_create.c:297
#4  0x00007ffff2fb871d in clone () at 
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#5  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7ffff7fab760 (LWP 26784)):
#0  0x00007ffff44cc763 in recvfrom () at ../sysdeps/unix/syscall-template.S:82
#1  0x000055555574b67d in recvfrom (so=0x555556bd2f50) at 
/usr/include/bits/socket2.h:77
#2  sorecvfrom (so=0x555556bd2f50) at /data/qemu/slirp/socket.c:498
#3  0x000055555574a160 in slirp_pollfds_poll (pollfds=0x555556511240, 
select_error=0) at /data/qemu/slirp/slirp.c:619
#4  0x000055555570ec99 in main_loop_wait (nonblocking=<value optimized out>) at 
/data/qemu/main-loop.c:514
#5  0x000055555577821d in main_loop (argc=<value optimized out>, argv=<value 
optimized out>, envp=<value optimized out>) at /data/qemu/vl.c:2002
#6  main (argc=<value optimized out>, argv=<value optimized out>, envp=<value 
optimized out>) at /data/qemu/vl.c:4334

Thread 1 blocks in recvfrom, not returning, not releasing the global lock.

Any idea?

Jan

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