Re: [Qemu-devel] iscsi / block segfault regression

[Peter Lieven]

Segfault happens if I specify format=iscsi in the -drive option group. In this 
case bdrv_swap() is called. Maybe there is a handling of bs->opaque missing?!

Peter


On 21.03.2013 12:03, Peter Lieven wrote:
> git bisect results:
>
> address@hidden:~/git/qemu$ git bisect bad
> f500a6d3c2b9ef0bb06d0080d91d8ed3c1d68f58 is the first bad commit
> commit f500a6d3c2b9ef0bb06d0080d91d8ed3c1d68f58
> Author: Kevin Wolf <address@hidden>
> Date:   Mon Nov 12 17:35:27 2012 +0100
>
>      block: Avoid second open for format probing
>
>      This fixes problems that are caused by the additional open/close cycle
>      of the existing format probing, for example related to qemu-nbd without
>      -t option or file descriptor passing.
>
>      Signed-off-by: Kevin Wolf <address@hidden>
>
> :100644 100644 c4f5566b5de6cfa371d7b60dd8b0e1a2da7fd55f 
> 2ec3afebfe6a6c12b573cba9ad36de800623fe6a M    block.c
>
>
> On 21.03.2013 11:45, Peter Lieven wrote:
> > Hi,
> >
> > I currently try to debug a regression in git master with iscsi that happens 
> > with some iscsi volumes.
> > I added debugging output to all aio calls into block/iscsi.c and it seems that 
> > immediately after
> > brdv_open something is overwriting bs->opaque with a new pointer.
> >
> > ~/git/qemu$ x86_64-softmmu/qemu-system-x86_64 -k de -enable-kvm -m 1024 -drive 
> > format=iscsi,file=iscsi://172.21.200.31/iqn.2001-05.com.equallogic:0-8a0906-3c0f4e007-dce91829d0450add-lieven-storage-migration-test-hd0/0,if=virtio,cache=writeback,aio=native
> >   -vnc :1 -boot dc -monitor stdio
> > iscsi open start
> > iscsi_full_connect_sync: iscsilun = 140063347224208, iscsilun->iscsi = 
> > 140063347225536, bs = 140063347221696, 
> > filename=iscsi://172.21.200.31/iqn.2001-05.com.equallogic:0-8a0906-3c0f4e007-dce91829d0450add-lieven-storage-migration-test-hd0/0
> > iscsi open finish ret=0
> > iscsi_aio_flush: iscsilun = 140063347230736, iscsilun->iscsi = 0, bs = 
> > 140063347221696, 
> > filename=iscsi://172.21.200.31/iqn.2001-05.com.equallogic:0-8a0906-3c0f4e007-dce91829d0450add-lieven-storage-migration-test-hd0/0
> > iscsi_aio_flush_acb: iscsilun = 140063347230736, iscsilun->iscsi = 0, bs = 
> > 140063347221696, 
> > filename=iscsi://172.21.200.31/iqn.2001-05.com.equallogic:0-8a0906-3c0f4e007-dce91829d0450add-lieven-storage-migration-test-hd0/0
> > Speicherzugriffsfehler (Speicherabzug geschrieben)
> >
> > bs address is unchanged, but iscsilun address is changed after connection it 
> > seems to an area with zeroed memory. the pointer to the iscsi context
> > is thus NULL.
> >
> > iscsilun, iscsilun->iscsi and bs are addresses.
> >
> > Peter