Messages in this thread | | | Subject | Re: [PATCH v3] ipc: introduce ipc_valid_object() helper to sort out IPC_RMID races | From | Davidlohr Bueso <> | Date | Wed, 18 Dec 2013 16:38:24 -0800 |
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On Wed, 2013-12-18 at 18:33 -0200, Rafael Aquini wrote: > After the locking semantics for the SysV IPC API got improved, a couple of > IPC_RMID race windows were opened because we ended up dropping the > 'kern_ipc_perm.deleted' check performed way down in ipc_lock(). > The spotted races got sorted out by re-introducing the old test within > the racy critical sections. > > This patch introduces ipc_valid_object() to consolidate the way we cope with > IPC_RMID races by using the same abstraction across the API implementation. > > Signed-off-by: Rafael Aquini <aquini@redhat.com> > Acked-by: Rik van Riel <riel@redhat.com> > Acked-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
[...]
> +/* > + * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths > + * where the respective ipc_ids.rwsem is not being held down. > + * Checks whether the ipc object is still around or if it's gone already, as > + * ipc_rmid() may have already freed the ID while the ipc lock was spinning. > + * Needs to be called with kern_ipc_perm.lock held -- exception made for one > + * checkpoint case at sys_semtimedop() as noted in code commentary. > + */ > +static inline bool ipc_valid_object(struct kern_ipc_perm *perm) > +{ > + return perm->deleted == 0; > +}
I would like to see .deleted being converted to bool while we're at it though, that return statement just bugs the hell out of me. Could you send a patch for that as well?
Thanks, Davidlohr
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