Re: [PATCH v4 12/22] lib/stackdepot: use read/write lock

[Marco Elver]

On Fri, Jan 12, 2024 at 09:24AM +0100, Marco Elver wrote:
> On Fri, 12 Jan 2024 at 03:38, Andrey Konovalov <andreyknvl@xxxxxxxxx> wrote:
[...]
> > Looks good to me from the functional perspective (modulo the
> > clarification comments I left above), but it would be great to get a
> > review from someone with a better understanding of the low-level
> > synchronization primitives.
> 
> Yes - and I'll have to rework this to use get_state_synchronize_rcu()
> after all. When it's ready for proper review I'll send an RFC patch.

The below should be what we want, this time without weird hacks.
NMI-safe RCU does work for this case.

I'll let the test robot beat on it then send the patch next week
(there's going to be a patch 1/2 to add stats counters as well).

Also note that the rwlock broke RT kernels, which is also fixed by the
below patch.

Thanks,
-- Marco