Re: [Qemu-devel] [PATCH 1/2] migration: implement io_set_aio_fd_handler function for RDMA QIOChannel

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> Lidong Chen <jemmy858585@gmail.com> wrote:
> > if qio_channel_rdma_readv return QIO_CHANNEL_ERR_BLOCK, the destination qemu
> > crash.
> >
> > The backtrace is:
> > (gdb) bt
> >     #0  0x0000000000000000 in ?? ()
> >     #1  0x00000000008db50e in qio_channel_set_aio_fd_handler (ioc=0x38111e0, ctx=0x3726080,
> >         io_read=0x8db841 <qio_channel_restart_read>, io_write=0x0, opaque=0x38111e0) at io/channel.c:
> >     #2  0x00000000008db952 in qio_channel_set_aio_fd_handlers (ioc=0x38111e0) at io/channel.c:438
> >     #3  0x00000000008dbab4 in qio_channel_yield (ioc=0x38111e0, condition=G_IO_IN) at io/channel.c:47
> >     #4  0x00000000007a870b in channel_get_buffer (opaque=0x38111e0, buf=0x440c038 "", pos=0, size=327
> >         at migration/qemu-file-channel.c:83
> >     #5  0x00000000007a70f6 in qemu_fill_buffer (f=0x440c000) at migration/qemu-file.c:299
> >     #6  0x00000000007a79d0 in qemu_peek_byte (f=0x440c000, offset=0) at migration/qemu-file.c:562
> >     #7  0x00000000007a7a22 in qemu_get_byte (f=0x440c000) at migration/qemu-file.c:575
> >     #8  0x00000000007a7c78 in qemu_get_be32 (f=0x440c000) at migration/qemu-file.c:655
> >     #9  0x00000000007a0508 in qemu_loadvm_state (f=0x440c000) at migration/savevm.c:2126
> >     #10 0x0000000000794141 in process_incoming_migration_co (opaque=0x0) at migration/migration.c:366
> >     #11 0x000000000095c598 in coroutine_trampoline (i0=84033984, i1=0) at util/coroutine-ucontext.c:1
> >     #12 0x00007f9c0db56d40 in ?? () from /lib64/libc.so.6
> >     #13 0x00007f96fe858760 in ?? ()
> >     #14 0x0000000000000000 in ?? ()
> >
> > RDMA QIOChannel not implement io_set_aio_fd_handler. so
> > qio_channel_set_aio_fd_handler will access NULL pointer.
> >
> > Signed-off-by: Lidong Chen <lidongchen@tencent.com>
> > ---
> 
> 
> Hi
> 
> could you resend, it don't compile for me :-(

This really sits after the other set of rdma changes.
I doubt this path is reachable without the previous set.

Dave
> 
> /mnt/kvm/qemu/cleanup/migration/rdma.c: In function ‘qio_channel_rdma_set_aio_fd_handler’:
> /mnt/kvm/qemu/cleanup/migration/rdma.c:2877:39: error: ‘QIOChannelRDMA’ {aka ‘struct QIOChannelRDMA’} has no member named ‘rdmain’; did you mean ‘rdma’?
>          aio_set_fd_handler(ctx, rioc->rdmain->comp_channel->fd,
>                                        ^~~~~~
>                                        rdma
> /mnt/kvm/qemu/cleanup/migration/rdma.c:2880:39: error: ‘QIOChannelRDMA’ {aka ‘struct QIOChannelRDMA’} has no member named ‘rdmaout’; did you mean ‘rdma’?
>          aio_set_fd_handler(ctx, rioc->rdmaout->comp_channel->fd,
>                                        ^~~~~~~
>                                        rdma
> make: *** [/mnt/kvm/qemu/cleanup/rules.mak:66: migration/rdma.o] Error 1
>   CC      migration/block.o
>   CC      ui/vnc.o
> 
> It seems like
> 
> > diff --git a/migration/rdma.c b/migration/rdma.c
> > index 92e4d30..dfa4f77 100644
> > --- a/migration/rdma.c
> > +++ b/migration/rdma.c
> > @@ -2963,6 +2963,21 @@ static GSource *qio_channel_rdma_create_watch(QIOChannel *ioc,
> >      return source;
> >  }
> >  
> > +static void qio_channel_rdma_set_aio_fd_handler(QIOChannel *ioc,
> > +                                                  AioContext *ctx,
> > +                                                  IOHandler *io_read,
> > +                                                  IOHandler *io_write,
> > +                                                  void *opaque)
> > +{
> > +    QIOChannelRDMA *rioc = QIO_CHANNEL_RDMA(ioc);
> > +    if (io_read) {
> > +        aio_set_fd_handler(ctx, rioc->rdmain->comp_channel->fd,
> 
>         this should be rioc->rdam->comp_channel
> 
> > +                           false, io_read, io_write, NULL, opaque);
> > +    } else {
> > +        aio_set_fd_handler(ctx, rioc->rdmaout->comp_channel->fd,
> 
> and this rioc-rdma->comp_channel
> 
> But will preffer if you confirm.
> 
> Thanks.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK