Re: [Qemu-devel] [PATCH v11 1/2] block/vxhs.c: Add support for a new block device type called "vxhs"

[Jeff Cody]

On Wed, Apr 12, 2017 at 01:10:10AM -0700, ashish mittal wrote:
> On Tue, Apr 11, 2017 at 12:47 PM, Jeff Cody <address@hidden> wrote:
> > On Mon, Apr 03, 2017 at 08:48:08PM -0700, Ashish Mittal wrote:
> >> Source code for the qnio library that this code loads can be downloaded 
> >> from:
> >> https://github.com/VeritasHyperScale/libqnio.git
> >>
> >> Sample command line using JSON syntax:
> >> ./x86_64-softmmu/qemu-system-x86_64 -name instance-00000008 -S -vnc 
> >> 0.0.0.0:0
> >> -k en-us -vga cirrus -device 
> >> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
> >> -msg timestamp=on
> >> 'json:{"driver":"vxhs","vdisk-id":"c3e9095a-a5ee-4dce-afeb-2a59fb387410",
> >> "server":{"host":"172.172.17.4","port":"9999"}}'
> >>
> >> Sample command line using URI syntax:
> >> qemu-img convert -f raw -O raw -n
> >> /var/lib/nova/instances/_base/0c5eacd5ebea5ed914b6a3e7b18f1ce734c386ad
> >> vxhs://192.168.0.1:9999/c6718f6b-0401-441d-a8c3-1f0064d75ee0
> >>
> >> Sample command line using TLS credentials (run in secure mode):
> >> ./qemu-io --object
> >> tls-creds-x509,id=tls0,dir=/etc/pki/qemu/vxhs,endpoint=client -c 'read
> >> -v 66000 2.5k' 'json:{"server.host": "127.0.0.1", "server.port": "9999",
> >> "vdisk-id": "/test.raw", "driver": "vxhs", "tls-creds":"tls0"}'
> >>
> >> Signed-off-by: Ashish Mittal <address@hidden>
> >
> > I was testing this some with blockdev-add and blockdev-del, and this
> > sequence causes a segfault:
> >
> > 1. blockdev-add vxhs image
> > 2. blockdev-del above image
> > 3. blockdev-add vxhs image  <--- segfaults
> >
> > Looking at it in gdb, this is an issue with libqnio.  The call to iio_fini()
> > is not sufficiently thorough in cleaning up resources.
> >
> > In nio_client.c, qnc_ctx is never freed, because there does not
> > seem to be a call such as 'qnc_driver_fini' that cleans up the allocated
> > qnio_client_ctx.
> >
> > Therefore, on the second call to iio_init, the libqnio internal variable
> > network_driver is NULL, because qnc_driver_init() returns NULL if it is
> > called when qnc_ctx is still initialized:
> >
> >
> >
> > lib/qnio/nio_client.c:
> >
> > 411 int
> > 412 iio_init(int32_t version, iio_cb_t cb)
> > 413 {
> >
> > [...]
> >
> > 432     apictx->network_driver = qnc_secure_driver_init(client_callback);
> > 433     nioDbg("Created API context.\n");
> > 434     return 0;
> > 435 }
> >
> > [...]
> >
> > 779 struct channel_driver *
> > 780 qnc_driver_init(qnio_notify client_notify)
> > 781 {
> > 782     if (qnc_ctx) {
> > 783         nioDbg("Driver already initialized");
> > 784         return NULL;
> > 785     }
> > 786
> >
> >
> > So two issues:
> >
> > A. iio_init() should check the returned pointer, and fail if NULL
> >
> > B. iio_fini() needs to clean everything up so that a new vxhs connection is
> >    possible. This likely means at least one new function in nio_client.c to
> >    clean up qnc_ctx.
> >
> > -Jeff
> 
> Thanks for reporting the issue and also suggesting the fix.
> I was able to reproduce the issue and have checked in a fix to libqnio.
> 
> This was the stack trace from the core -
> 
> Program terminated with signal 11, Segmentation fault.
> #0  0x00007f12083a3afa in iio_channel_open (uri=0x7f120c57eb70
> "of://127.0.0.1:9999", cacert=0x0, client_key=0x0, client_cert=0x0) at
> lib/qnio/iioapi.c:105
> #1  0x00007f12083a470a in iio_open (uri=0x7f120d121be0
> "of://127.0.0.1:9999", devid=0x7f120baa4bb0 "/test.raw", flags=0,
> cacert=0x0, client_key=0x0, client_cert=0x0) at lib/qnio/iioapi.c:520
> #2  0x00007f12091bf7a3 in vxhs_open (bs=<optimized out>,
> options=<optimized out>, bdrv_flags=<optimized out>,
> errp=0x7ffdf1cafd70) at block/vxhs.c:388
> #3  0x00007f120916cf14 in bdrv_open_driver
> (address@hidden, address@hidden <bdrv_vxhs>,
> node_name=<optimized out>, address@hidden,
> open_flags=8194,
>     address@hidden) at block.c:1011
> #4  0x00007f120917079f in bdrv_open_common (errp=0x7ffdf1cafe28,
> options=0x7f120daa6840, file=0x0, bs=0x7f120b1481b0) at block.c:1250
> #5  bdrv_open_inherit (filename=<optimized out>, address@hidden,
> address@hidden, options=0x7f120daa6840,
> address@hidden, flags=40962, address@hidden,
>     address@hidden, address@hidden)
> at block.c:2413
> #6  0x00007f1209171663 in bdrv_open (address@hidden,
> address@hidden, address@hidden,
> flags=<optimized out>, address@hidden)
>     at block.c:2505
> #7  0x00007f1208f9f026 in bds_tree_init
> (address@hidden, address@hidden)
> at blockdev.c:656
> #8  0x00007f1208fa4e5b in qmp_blockdev_add
> (address@hidden, address@hidden)
> at blockdev.c:3885
> ...
> 
> Please test again with refreshed libqnio and let me know in case of issues.
>

Hi Ashish,

I updated libqnio to 87b641b, and I can confirm that it fixes the issue I
was seeing above.

Thanks,
Jeff