Re: [Qemu-devel] virtio-vhost-user with virtio-scsi: end-to-end setup

[Wodkowski, PawelX]

Hi Nikos,

About SPKD backtrace you got. There is something wrong with IO channel 
allocation.
SPKD vhost-scsi  should check the result of 
spdk_scsi_dev_allocate_io_channels() in
spdk_vhost_scsi_dev_add_tgt(). But this result is not checked :(
You can add some check or assert there.

Paweł

> 
> But, now, I have really hit a roadblock. I get a segfault, I run the
> exact same commands as shown above, and end up with this backtrace:
> 
> -- cut here --
> 
> #0  0x000000000046ae42 in spdk_bdev_get_io (channel=0x30) at bdev.c:920
> #1  0x000000000046c985 in spdk_bdev_readv_blocks (desc=0x93f8a0,
> ch=0x0,
>     iov=0x7ffff2fb7c88, iovcnt=1, offset_blocks=0, num_blocks=8,
>     cb=0x453e1a <spdk_bdev_scsi_task_complete_cmd>,
> cb_arg=0x7ffff2fb7bc0) at bdev.c:1696
> #2  0x000000000046c911 in spdk_bdev_readv (desc=0x93f8a0, ch=0x0,
> iov=0x7ffff2fb7c88,
>     iovcnt=1, offset=0, nbytes=4096, cb=0x453e1a
> <spdk_bdev_scsi_task_complete_cmd>,
>     cb_arg=0x7ffff2fb7bc0) at bdev.c:1680
> #3  0x0000000000453fe2 in spdk_bdev_scsi_read (bdev=0x941c80,
> bdev_desc=0x93f8a0,
>     bdev_ch=0x0, task=0x7ffff2fb7bc0, lba=0, len=8) at scsi_bdev.c:1317
> #4  0x000000000045462e in spdk_bdev_scsi_readwrite (task=0x7ffff2fb7bc0,
> lba=0,
>     xfer_len=8, is_read=true) at scsi_bdev.c:1477
> #5  0x0000000000454c95 in spdk_bdev_scsi_process_block
> (task=0x7ffff2fb7bc0)
>     at scsi_bdev.c:1662
> #6  0x00000000004559ce in spdk_bdev_scsi_execute (task=0x7ffff2fb7bc0)
>     at scsi_bdev.c:2029
> #7  0x00000000004512e4 in spdk_scsi_lun_execute_task (lun=0x93f830,
> task=0x7ffff2fb7bc0)
>     at lun.c:162
> #8  0x0000000000450a87 in spdk_scsi_dev_queue_task (dev=0x713c80
> <g_devs>,
>     task=0x7ffff2fb7bc0) at dev.c:264
> #9  0x000000000045ae48 in task_submit (task=0x7ffff2fb7bc0) at
> vhost_scsi.c:268
> #10 0x000000000045c2b8 in process_requestq (svdev=0x7ffff31d9dc0,
> vq=0x7ffff31d9f40)
>     at vhost_scsi.c:649
> #11 0x000000000045c4ad in vdev_worker (arg=0x7ffff31d9dc0) at
> vhost_scsi.c:685
> #12 0x00000000004797f2 in _spdk_reactor_run (arg=0x944540) at
> reactor.c:471
> #13 0x0000000000479dad in spdk_reactors_start () at reactor.c:633
> #14 0x00000000004783b1 in spdk_app_start (opts=0x7fffffffe390,
>     start_fn=0x404df8 <vhost_started>, arg1=0x0, arg2=0x0) at app.c:570
> #15 0x0000000000404ec0 in main (argc=7, argv=0x7fffffffe4f8) at vhost.c:115
> 
> -- cut here --
> 
> I have not yet been able to debug this, it’s most probably my bug, but I
> am wondering whether there could be a conflict between the two distinct
> virtio drivers: (1) the pre-existing one in the SPDK virtio library
> under lib/virtio/, and (2) the one I copied into lib/vhost/rte_vhost/ as
> part of the vhost library.
>