Re: [Qemu-devel] [PATCH v2 6/7] virtio-blk: Unify {non-, }dataplane's request handlings

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Tue, Jul 01, 2014 at 01:29:36PM +0200, Max Reitz wrote:
> On 17.06.2014 08:32, Fam Zheng wrote:
> >This drops request handling code from dataplane, and uses code from
> >hw/block/virtio-blk.c.
> >
> >It starts to use multiwrite as non-dataplane does.
> >
> >Dataplane sets VirtIOBlock.complete_request to vring version, and calls
> >into non-dataplane's process handling. In complete_request_early,
> >qiov.size is added to vring push length, because it's also called in rw
> >completion now.
> >
> >Signed-off-by: Fam Zheng <famz@redhat.com>
> >---
> >  hw/block/dataplane/virtio-blk.c | 183 +++++-----------------------------------
> >  1 file changed, 19 insertions(+), 164 deletions(-)
> 
> Is it intended that qemu segfaults after this commit with x-data-plane=on?
> 
> $ ./qemu-img create -f qcow2 test.qcow2 64M
> $ x86_64-softmmu/qemu-system-x86_64 -drive if=none,file=test.qcow2,id=drv0
> -device virtio-blk-pci,drive=drv0,x-data-plane=on
> [1]    4604 segmentation fault  x86_64-softmmu/qemu-system-x86_64 -drive
> if=none,file=test.qcow2,id=drv0
> 
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x7fffd75ff700 (LWP 5217)]
> 0x00005555556373af in virtio_blk_rw_complete (opaque=0x5555565ff5e0, ret=0)
> at hw/block/virtio-blk.c:99
> 99          bdrv_acct_done(req->dev->bs, &req->acct);
> (gdb) print req
> $1 = (VirtIOBlockReq *) 0x5555565ff5e0
> (gdb) print req->dev
> $2 = (VirtIOBlock *) 0x0
> (gdb) bt
> #0  0x00005555556373af in virtio_blk_rw_complete (opaque=0x5555565ff5e0,
> ret=0) at hw/block/virtio-blk.c:99
> #1  0x0000555555840ebe in bdrv_co_em_bh (opaque=0x5555566152d0) at
> block.c:4675
> #2  0x000055555583de77 in aio_bh_poll (ctx=ctx@entry=0x5555563a8150) at
> async.c:81
> #3  0x000055555584b7a7 in aio_poll (ctx=0x5555563a8150,
> blocking=blocking@entry=true) at aio-posix.c:188
> #4  0x00005555556e520e in iothread_run (opaque=0x5555563a7fd8) at
> iothread.c:41
> #5  0x00007ffff42ba124 in start_thread () from /usr/lib/libpthread.so.0
> #6  0x00007ffff16d14bd in clone () from /usr/lib/libc.so.6

I'm looking into this and will send a patch to fix it.

Stefan

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