Re: [Qemu-devel] [PULL v2 for-2.4 v2 5/7] AioContext: fix broken ctx->dispatching optimization

[Paolo Bonzini <pbonzini@redhat.com>]

On 23/07/2015 16:14, Cornelia Huck wrote:
> (gdb) bt 
> #0  0x000003fffc5871b4 in pthread_cond_wait@@GLIBC_2.3.2 ()
>    from /lib64/libpthread.so.0
> #1  0x000000008024cfca in qemu_cond_wait (cond=cond@entry=0x9717d950, 
>     mutex=mutex@entry=0x9717d920)
>     at /data/git/yyy/qemu/util/qemu-thread-posix.c:132
> #2  0x000000008025e83a in rfifolock_lock (r=0x9717d920)
>     at /data/git/yyy/qemu/util/rfifolock.c:59
> #3  0x00000000801b78fa in aio_context_acquire (ctx=<optimized out>)
>     at /data/git/yyy/qemu/async.c:331
> #4  0x000000008007ceb4 in virtio_blk_data_plane_start (s=0x9717d710)
>     at /data/git/yyy/qemu/hw/block/dataplane/virtio-blk.c:285
> #5  0x000000008007c64a in virtio_blk_handle_output (vdev=<optimized out>, 
>     vq=<optimized out>) at /data/git/yyy/qemu/hw/block/virtio-blk.c:599
> #6  0x00000000801c56dc in qemu_iohandler_poll (pollfds=0x97142800, 
>     ret=ret@entry=1) at /data/git/yyy/qemu/iohandler.c:126
> #7  0x00000000801c5178 in main_loop_wait (nonblocking=<optimized out>)
>     at /data/git/yyy/qemu/main-loop.c:494
> #8  0x0000000080013ee2 in main_loop () at /data/git/yyy/qemu/vl.c:1902
> #9  main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>)
>     at /data/git/yyy/qemu/vl.c:4653
> 
> I've stripped down the setup to the following commandline:
> 
> /data/git/yyy/qemu/build/s390x-softmmu/qemu-system-s390x  -machine
> s390-ccw-virtio-2.4,accel=kvm,usb=off -m 1024 -smp
> 4,sockets=4,cores=1,threads=1 -nographic -drive
> file=/dev/sda,if=none,id=drive-virtio-disk0,format=raw,serial=ccwzfcp1,cache=none,aio=native
> -device
> virtio-blk-ccw,scsi=off,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1,x-data-plane=on

What's the backtrace like for the other threads?  This is almost
definitely a latent bug somewhere else.


Paolo