Re: [Qemu-devel] [PATCH v2 3/4] memory-backend-file: improve error handling

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jun 17, 2014 at 06:09:08PM +0800, Hu Tao wrote:
> On Tue, Jun 17, 2014 at 12:03:13PM +0200, Igor Mammedov wrote:
> > On Mon, 16 Jun 2014 18:05:43 +0800
> > Hu Tao <hutao@cn.fujitsu.com> wrote:
> > 
> > > This patch fixes two problems of memory-backend-file:
> > > 
> > > 1. If user adds a memory-backend-file object using object_add command,
> > >    specifying a non-existing directory for property mem-path, qemu
> > >    will core dump with message:
> > > 
> > >      /nonexistingdir: No such file or directory
> > >      Bad ram offset fffffffffffff000
> > >      Aborted (core dumped)
> > > 
> > > 2. If user adds a memory-backend-file object using object_add command,
> > >    specifying a size that is less than huge page size, qemu
> > >    will core dump with message:
> > > 
> > >      Bad ram offset fffffffffffff000
> > >      Aborted (core dumped)
> > > 
> > > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> > > ---
> > >  exec.c | 26 ++++++++++++++++++--------
> > >  1 file changed, 18 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/exec.c b/exec.c
> > > index 8705cc5..a6afb4d 100644
> > > --- a/exec.c
> > > +++ b/exec.c
> > [...]
> > > @@ -1308,7 +1311,14 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
> > >          return -1;
> > >      }
> > >  
> > > -    return ram_block_add(new_block);
> > > +    addr = ram_block_add(new_block);
> > > +    if (addr == -1) {
> > how this hunk is relevant to commit message?
> > 
> > and more important in what case ram_block_add() returns -1?
> 
> See patch 03 int v1(titled [PATCH RFC 3/4] exec: don't exit unconditionally if failed to allocate memory)
> It is not included in this version but we'll fix it after the merge.

So maybe defer this hunk to after the merge too.

> > 
> > > +        g_free(new_block);
> > > +        error_setg(errp, "failed to allocate memory\n");
> > > +        return -1;
> > > +    }
> > > +
> > > +    return addr;
> > >  }
> > >  #endif
> > >