Re: [RFC 00/12] locking: Separate lock tracepoints from lockdep/lock_stat (v1)

[Waiman Long]

On 2/9/22 14:45, Namhyung Kim wrote:
> On Wed, Feb 9, 2022 at 11:28 AM Mathieu Desnoyers
> <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
> > ----- On Feb 9, 2022, at 2:22 PM, Namhyung Kim namhyung@xxxxxxxxxx wrote:
> > > I'm also concerning dynamic allocated locks in a data structure.
> > > If we keep the info in a hash table, we should delete it when the
> > > lock is gone.  I'm not sure we have a good place to hook it up all.
> > I was wondering about this use case as well. Can we make it mandatory to
> > declare the lock "class" (including the name) statically, even though the
> > lock per-se is allocated dynamically ? Then the initialization of the lock
> > embedded within the data structure would simply refer to the lock class
> > definition.
> Isn't it still the same if we have static lock classes that the entry needs
> to be deleted from the hash table when it frees the data structure?
> I'm more concerned about free than alloc as there seems to be no
> API to track that in a place.

We may have to invent some new APIs to do that. For example, 
spin_lock_exit() can be the counterpart of spin_lock_init() and so on. 
Of course, existing kernel code have to be modified to designate the 
point after which a lock is no longer being used or is freed.

Cheers,
Longman