On Mon, Feb 15, 2021 at 02:12:30PM +0100, Johannes Berg wrote:
> On Mon, 2021-02-15 at 11:44 +0100, Peter Zijlstra wrote:
> >
> > I think something like so will work, but please double check.
>
> Yeah, that looks better.
>
> > +++ b/include/linux/lockdep.h
> > @@ -294,11 +294,15 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
> >
> > #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
> >
> > -#define lockdep_assert_held(l) do { \
> > - WARN_ON(debug_locks && !lockdep_is_held(l)); \
> > +#define lockdep_assert_held(l) do { \
> > + WARN_ON(debug_locks && lockdep_is_held(l) == 0)); \
> > } while (0)
>
> That doesn't really need to change? It's the same.
Correct, but I found it more symmetric vs the not implementation below.
> > -#define lockdep_assert_held_write(l) do { \
> > +#define lockdep_assert_not_held(l) do { \
> > + WARN_ON(debug_locks && lockdep_is_held(l) == 1)); \
> > + } while (0)
> > +
> > +#define lockdep_assert_held_write(l) do { \
> > WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
> > } while (0)
> >
> > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> > index c1418b47f625..983ba206f7b2 100644
> > --- a/kernel/locking/lockdep.
> > +++ b/kernel/locking/lockdep.c
> > @@ -5467,7 +5467,7 @@ noinstr int lock_is_held_type(const struct lockdep_map *lock, int read)
> > int ret = 0;
> >
> > if (unlikely(!lockdep_enabled()))
> > - return 1; /* avoid false negative lockdep_assert_held() */
> > + return -1; /* avoid false negative lockdep_assert_held() */
>
> Maybe add lockdep_assert_not_held() to the comment, to explain the -1
> (vs non-zero)?
Yeah, or frob a '*' in there.
On Mon, 2021-02-15 at 17:04 +0100, Peter Zijlstra wrote:
> On Mon, Feb 15, 2021 at 02:12:30PM +0100, Johannes Berg wrote:
> > On Mon, 2021-02-15 at 11:44 +0100, Peter Zijlstra wrote:
> > > I think something like so will work, but please double check.
> >
> > Yeah, that looks better.
> >
> > > +++ b/include/linux/lockdep.h
> > > @@ -294,11 +294,15 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
> > >
> > > #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
> > >
> > > -#define lockdep_assert_held(l) do { \
> > > - WARN_ON(debug_locks && !lockdep_is_held(l)); \
> > > +#define lockdep_assert_held(l) do { \
> > > + WARN_ON(debug_locks && lockdep_is_held(l) == 0)); \
> > > } while (0)
> >
> > That doesn't really need to change? It's the same.
>
> Correct, but I found it more symmetric vs the not implementation below.
Fair enough. One might argue that you should have an
enum lockdep_lock_state {
LOCK_STATE_NOT_HELD, /* 0 now */
LOCK_STATE_HELD, /* 1 now */
LOCK_STATE_UNKNOWN, /* -1 with your patch but might as well be 2 */
};
:)
johannes
On 2/15/21 9:10 AM, Johannes Berg wrote:
> On Mon, 2021-02-15 at 17:04 +0100, Peter Zijlstra wrote:
>> On Mon, Feb 15, 2021 at 02:12:30PM +0100, Johannes Berg wrote:
>>> On Mon, 2021-02-15 at 11:44 +0100, Peter Zijlstra wrote:
>>>> I think something like so will work, but please double check.
>>>
>>> Yeah, that looks better.
>>>
>>>> +++ b/include/linux/lockdep.h
>>>> @@ -294,11 +294,15 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
>>>>
>>>> #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
>>>>
>>>> -#define lockdep_assert_held(l) do { \
>>>> - WARN_ON(debug_locks && !lockdep_is_held(l)); \
>>>> +#define lockdep_assert_held(l) do { \
>>>> + WARN_ON(debug_locks && lockdep_is_held(l) == 0)); \
>>>> } while (0)
>>>
>>> That doesn't really need to change? It's the same.
>>
>> Correct, but I found it more symmetric vs the not implementation below.
>
> Fair enough. One might argue that you should have an
>
> enum lockdep_lock_state {
> LOCK_STATE_NOT_HELD, /* 0 now */
> LOCK_STATE_HELD, /* 1 now */
> LOCK_STATE_UNKNOWN, /* -1 with your patch but might as well be 2 */
> };
>
> :)
>
Thank you both. Picking this back up. Will send v2 incorporating
your comments and suggestions.
thanks,
-- Shuah