[PATCH v2 42/47] drm/ttm: introduce pool_shrink_rwsem

[Muchun Song]

> On Jul 24, 2023, at 17:43, Qi Zheng <zhengqi.arch at bytedance.com> wrote:
> 
> Currently, the synchronize_shrinkers() is only used by TTM pool. It only
> requires that no shrinkers run in parallel.
> 
> After we use RCU+refcount method to implement the lockless slab shrink,
> we can not use shrinker_rwsem or synchronize_rcu() to guarantee that all
> shrinker invocations have seen an update before freeing memory.
> 
> So we introduce a new pool_shrink_rwsem to implement a private
> synchronize_shrinkers(), so as to achieve the same purpose.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch at bytedance.com>

Reviewed-by: Muchun Song <songmuchun at bytedance.com>