On Mon, Jan 29, 2024 at 5:42 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
>
> Move pool refcounting functions into the pool section. First the
> destroy functions, then the get and put which uses them.
>
> __zswap_pool_empty() has an upward reference to the global
> zswap_pools, to sanity check it's not the currently active pool that's
> being freed. That gets the forward decl for zswap_pool_cuyrrent().
nit: zswap_pool_cuyrrent() -> zswap_pool_current() :-)
Also, would it make sense to move zswap_pool_current() above
__zswap_pool_empty() to get rid of the forward declaration? I guess
it's now grouped with current_get() etc. - those don't seem to use the
empty check, so maybe they can also go above __zswap_pool_empty()?
>
> This puts the get and put function above all callers, so kill the
> forward decls as well.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---
> mm/zswap.c | 94 +++++++++++++++++++++++++++---------------------------
> 1 file changed, 47 insertions(+), 47 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 805d9a35f633..33775f2224b7 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -278,8 +278,6 @@ static inline struct zswap_tree *swap_zswap_tree(swp_entry_t swp)
>
> static int zswap_writeback_entry(struct zswap_entry *entry,
> swp_entry_t swpentry);
> -static int zswap_pool_get(struct zswap_pool *pool);
> -static void zswap_pool_put(struct zswap_pool *pool);
>
> static bool zswap_is_full(void)
> {
> @@ -472,6 +470,53 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
> kfree(pool);
> }
>
> +static void __zswap_pool_release(struct work_struct *work)
> +{
> + struct zswap_pool *pool = container_of(work, typeof(*pool),
> + release_work);
> +
> + synchronize_rcu();
> +
> + /* nobody should have been able to get a kref... */
> + WARN_ON(kref_get_unless_zero(&pool->kref));
> +
> + /* pool is now off zswap_pools list and has no references. */
> + zswap_pool_destroy(pool);
> +}
> +
> +static struct zswap_pool *zswap_pool_current(void);
> +
> +static void __zswap_pool_empty(struct kref *kref)
> +{
> + struct zswap_pool *pool;
> +
> + pool = container_of(kref, typeof(*pool), kref);
> +
> + spin_lock(&zswap_pools_lock);
> +
> + WARN_ON(pool == zswap_pool_current());
> +
> + list_del_rcu(&pool->list);
> +
> + INIT_WORK(&pool->release_work, __zswap_pool_release);
> + schedule_work(&pool->release_work);
> +
> + spin_unlock(&zswap_pools_lock);
> +}
> +
> +static int __must_check zswap_pool_get(struct zswap_pool *pool)
> +{
> + if (!pool)
> + return 0;
> +
> + return kref_get_unless_zero(&pool->kref);
> +}
> +
> +static void zswap_pool_put(struct zswap_pool *pool)
> +{
> + kref_put(&pool->kref, __zswap_pool_empty);
> +}
> +
> /* should be called under RCU */
> #ifdef CONFIG_MEMCG
> static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
> @@ -1122,51 +1167,6 @@ static void shrink_worker(struct work_struct *w)
> zswap_pool_put(pool);
> }
>
> -static int __must_check zswap_pool_get(struct zswap_pool *pool)
> -{
> - if (!pool)
> - return 0;
> -
> - return kref_get_unless_zero(&pool->kref);
> -}
> -
> -static void __zswap_pool_release(struct work_struct *work)
> -{
> - struct zswap_pool *pool = container_of(work, typeof(*pool),
> - release_work);
> -
> - synchronize_rcu();
> -
> - /* nobody should have been able to get a kref... */
> - WARN_ON(kref_get_unless_zero(&pool->kref));
> -
> - /* pool is now off zswap_pools list and has no references. */
> - zswap_pool_destroy(pool);
> -}
> -
> -static void __zswap_pool_empty(struct kref *kref)
> -{
> - struct zswap_pool *pool;
> -
> - pool = container_of(kref, typeof(*pool), kref);
> -
> - spin_lock(&zswap_pools_lock);
> -
> - WARN_ON(pool == zswap_pool_current());
> -
> - list_del_rcu(&pool->list);
> -
> - INIT_WORK(&pool->release_work, __zswap_pool_release);
> - schedule_work(&pool->release_work);
> -
> - spin_unlock(&zswap_pools_lock);
> -}
> -
> -static void zswap_pool_put(struct zswap_pool *pool)
> -{
> - kref_put(&pool->kref, __zswap_pool_empty);
> -}
> -
> /*********************************
> * param callbacks
> **********************************/
> --
> 2.43.0
>
