On Fri, 2010-10-29 at 18:18 +0100, Jeremy Fitzhardinge wrote:
> On 10/28/2010 04:39 AM, Vasiliy Kulikov wrote:
> > put_user() may fail. In this case propagate error code from
> > privcmd_ioctl_mmap_batch().
>
> Thanks for looking at this. I'm in two minds about this; the existing
> logic is such that these put_users can only fail if something else has
> already failed and its returning an error. I guess it would be useful
> to get an EFAULT if you've got a problem writing back the results.
>
> IanC, any opinion?
Not a strong one.
Perhaps what we really want in this case is for traverse_pages to return
the total number of callback failures it encountered rather than
aborting after the first failure?
On the other hand you are correct that gather_array() has already
touched all the pages which we are going to be touching here so how
likely is a new failure at this point anyway?
Ian.
>
> Thanks,
> J
>
> > Signed-off-by: Vasiliy Kulikov <segooon@xxxxxxxxx>
> > ---
> > Compile tested.
> >
> > drivers/xen/xenfs/privcmd.c | 8 ++------
> > 1 files changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/xen/xenfs/privcmd.c b/drivers/xen/xenfs/privcmd.c
> > index f80be7f..2eb04c8 100644
> > --- a/drivers/xen/xenfs/privcmd.c
> > +++ b/drivers/xen/xenfs/privcmd.c
> > @@ -266,9 +266,7 @@ static int mmap_return_errors(void *data, void *state)
> > xen_pfn_t *mfnp = data;
> > struct mmap_batch_state *st = state;
> >
> > - put_user(*mfnp, st->user++);
> > -
> > - return 0;
> > + return put_user(*mfnp, st->user++);
> > }
> >
> > static struct vm_operations_struct privcmd_vm_ops;
> > @@ -323,10 +321,8 @@ static long privcmd_ioctl_mmap_batch(void __user *udata)
> > up_write(&mm->mmap_sem);
> >
> > if (state.err > 0) {
> > - ret = 0;
> > -
> > state.user = m.arr;
> > - traverse_pages(m.num, sizeof(xen_pfn_t),
> > + ret = traverse_pages(m.num, sizeof(xen_pfn_t),
> > &pagelist,
> > mmap_return_errors, &state);
> > }
>
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