[Qemu-devel] Re: [PATCH]hw/xen_disk: ioreq not finished on error

[Stefano Stabellini]

On Mon, 28 Mar 2011, Feiran Zheng wrote:
> On Mon, Mar 28, 2011 at 9:42 PM, Stefano Stabellini
> <address@hidden> wrote:
> > On Sun, 27 Mar 2011, Feiran Zheng wrote:
> >> Bug fix: routines 'ioreq_runio_qemu_sync' and 'ioreq_runio_qemu_aio'
> >> won't call 'ioreq_unmap' or 'ioreq_finish' on errors, leaving ioreq in
> >> the blkdev->inflight list and a leak.
> >>
> >> Signed-off-by: Feiran Zheng <address@hidden>
> >> ---
> >>  hw/xen_disk.c |   22 +++++++++++++++++-----
> >>  1 files changed, 17 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/hw/xen_disk.c b/hw/xen_disk.c
> >> index 445bf03..7940fab 100644
> >> --- a/hw/xen_disk.c
> >> +++ b/hw/xen_disk.c
> >> @@ -309,8 +309,10 @@ static int ioreq_runio_qemu_sync(struct ioreq *ioreq)
> >>      int i, rc, len = 0;
> >>      off_t pos;
> >>
> >> -    if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1)
> >> -     goto err;
> >> +    if (ioreq->req.nr_segments) {
> >> +     if (ioreq_map(ioreq) == -1)
> >> +         goto err_no_map;
> >> +    }
> >>      if (ioreq->presync)
> >>       bdrv_flush(blkdev->bs);
> >>
> >
> > this change is just to make the code clearer and easier to read, right?
> 
> I think so.
> 
> >
> >
> >> @@ -364,6 +366,9 @@ static int ioreq_runio_qemu_sync(struct ioreq *ioreq)
> >>      return 0;
> >>
> >>  err:
> >> +    ioreq_unmap(ioreq);
> >> +err_no_map:
> >> +    ioreq_finish(ioreq);
> >>      ioreq->status = BLKIF_RSP_ERROR;
> >>      return -1;
> >>  }
> >> @@ -392,8 +397,10 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
> >>  {
> >>      struct XenBlkDev *blkdev = ioreq->blkdev;
> >>
> >> -    if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1)
> >> -     goto err;
> >> +    if (ioreq->req.nr_segments) {
> >> +     if (ioreq_map(ioreq) == -1)
> >> +         goto err_no_map;
> >> +    }
> >>
> >>      ioreq->aio_inflight++;
> >>      if (ioreq->presync)
> >> @@ -425,9 +432,14 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
> >>      qemu_aio_complete(ioreq, 0);
> >>
> >>      return 0;
> >> +
> >> +err_no_map:
> >> +    ioreq_finish(ioreq);
> >> +    ioreq->status = BLKIF_RSP_ERROR;
> >> +    return -1;
> >>
> >
> > why aren't you calling ioreq_unmap before ioreq_finish, like in the
> > previous case?
> >
> >
> >
> It seems not a must but if call qemu_aio_complete, the error info can
> be printed, I thought it may be helpful.

I am not sure I understand what you mean here because in case of error
we don't call qemu_aio_complete at all in the err_no_map code path.