Oleg Nesterov <o...@redhat.com> writes: > alloc_pid() does get_pid_ns() beforehand but forgets to put_pid_ns() > if it fails because disable_pid_allocation() was called by the exiting > child_reaper. We can move get_pid_ns() down to successful return. > > While at it, simplify/cleanup the "goto out" mess, no need to confuse > the success/error return paths. > > Signed-off-by: Oleg Nesterov <o...@redhat.com> > --- > kernel/pid.c | 7 +++---- > 1 files changed, 3 insertions(+), 4 deletions(-) > > diff --git a/kernel/pid.c b/kernel/pid.c > index 9b9a266..dfc2f3b 100644 > --- a/kernel/pid.c > +++ b/kernel/pid.c > @@ -320,7 +320,6 @@ struct pid *alloc_pid(struct pid_namespace *ns) > goto out_free; > } > > - get_pid_ns(ns); > atomic_set(&pid->count, 1); > for (type = 0; type < PIDTYPE_MAX; ++type) > INIT_HLIST_HEAD(&pid->tasks[type]); > @@ -336,7 +335,7 @@ struct pid *alloc_pid(struct pid_namespace *ns) > } > spin_unlock_irq(&pidmap_lock); > > -out: > + get_pid_ns(ns);
Moving the label and changing the goto out logic is gratuitous confusing and I think it probably even generates worse code. Furthermore multiple exits make adding debugging code more difficult. Moving get_pid_ns down does close a leak in the error handling path. However at the moment my I can't figure out if it is safe to move get_pid_ns elow hlist_add_head_rcu. Because once we are on the rcu list the pid is findable, and being publicly visible with a bad refcount could cause problems. The increment of ns->nr_hashed after the adding to the rcu list is only safe because we always access ns->nr_hashed with the pidmap_lock held. Eric > return pid; > > out_unlock: > @@ -346,8 +345,8 @@ out_free: > free_pidmap(pid->numbers + i); > > kmem_cache_free(ns->pid_cachep, pid); > - pid = NULL; > - goto out; > +out: > + return NULL; > } > > void disable_pid_allocation(struct pid_namespace *ns) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
