Re: [PATCH] libdiskfs: fix reference counting of peropen objects

[Justus Winter]

Quoting Neal H. Walfield (2014-08-29 11:55:07)
> At Fri, 29 Aug 2014 11:33:44 +0200,
> Justus Winter wrote:
> > Previously, peropen objects were created with a reference count of
> > zero.  Therefore, if diskfs_create_protid fails, passing such an
> > object to diskfs_release_peropen would lead to a reference count
> > underflow.
> > 
> > * libdiskfs/peropen-make.c (diskfs_peropen_make): Initialize reference
> > count to one.
> > * libdiskfs/protid-make.c (diskfs_start_protid): And consume this
> > reference on success.  Update comment.
> 
> Are references really consumed?  (I think 'released' is the right
> word.)

Yes, they are.  If diskfs_create_protid succeeds, the reference is in
the belly of the newly created protid object.

Also, this terminology is used elsewhere in the Hurd.  Functions that
contain the term 'release' in their name decrement a reference count
(e.g. diskfs_release_peropen).  On the other hand, 'consume' indicates
that a reference is absorbed, e.g. in exec/exec.c (use1),
pfinet/socket.c (make_sock_user), and trans/fakeroot.c (new_node).

Cheers,
Justus