On Sat, Apr 13, 2013 at 8:41 AM, Anatol Pomozov <[email protected]> wrote: > > Does it make sense to move it to a separate function in kref.h? > > /** Useful when kref_get is racing with kref_put and refcounter might be 0 */ > int kref_get_not_zero(kref* ref) { > return atomic_inc_not_zero(&kref->refcount); > }
It turns out we have that, except it's called "unless_zero", because
it uses "atomic_add_unless(x,1,0)", rather than the simplified
"atomic_inc_not_zero(x)".
> or maybe instead change default behavior of kref_get() to
> atomic_inc_not_zero and force callers check the return value from
> kref_get()?
That would be painful, and _most_ users should have a preexisting
refcount. So it's probably better in the long run to just keep the
warning (but perhaps fix it to be SMP-safe). So I think the part of
your patch that made kref_get() use atomic_inc_return() is probably a
good idea regardless.
Also, I changed my patch to be minimal, and not change other users of
kobject_get(). So other users (not kset_find_obj()) will continue to
get the warning, and kset_find_obj() uses the safe version. So this is
what I'm planning on committing as the minimal patch and marking for
stable. The rest (including that atomic_inc_return() in kref_get)
would be cleanup.
Can you give this a quick test?
Linus
patch.diff
Description: Binary data
