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

Waiman Long
2022-02-09T20:18:00Z

On 2/9/22 14:45, Namhyung Kim wrote:
> On Wed, Feb 9, 2022 at 11:28 AM Mathieu Desnoyers
> <mathieu.desnoyers@efficios.com> wrote:
>> ----- On Feb 9, 2022, at 2:22 PM, Namhyung Kim namhyung@kernel.org 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