This commit introduces refcount and completion_wait fields to struct shrinker to manage the life cycle of shrinker instance. Just a preparation work for implementing the lockless slab shrink, no functional changes. Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> --- include/linux/shrinker.h | 11 +++++++++++ mm/vmscan.c | 5 +++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 4094e4c44e80..7bfeb2f25246 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -4,6 +4,8 @@ #include <linux/atomic.h> #include <linux/types.h> +#include <linux/refcount.h> +#include <linux/completion.h> /* * This struct is used to pass information from page reclaim to the shrinkers. @@ -70,6 +72,9 @@ struct shrinker { int seeks; /* seeks to recreate an obj */ unsigned flags; + refcount_t refcount; + struct completion completion_wait; + void *private_data; /* These are for internal use */ @@ -118,6 +123,12 @@ struct shrinker *shrinker_alloc_and_init(count_objects_cb count, void shrinker_free(struct shrinker *shrinker); void unregister_and_free_shrinker(struct shrinker *shrinker); +static inline void shrinker_put(struct shrinker *shrinker) +{ + if (refcount_dec_and_test(&shrinker->refcount)) + complete(&shrinker->completion_wait); +} + #ifdef CONFIG_SHRINKER_DEBUG extern int shrinker_debugfs_add(struct shrinker *shrinker); extern struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker, diff --git a/mm/vmscan.c b/mm/vmscan.c index 3a8d50ad6ff6..6f9c4750effa 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -740,6 +740,8 @@ void free_prealloced_shrinker(struct shrinker *shrinker) void register_shrinker_prepared(struct shrinker *shrinker) { down_write(&shrinker_rwsem); + refcount_set(&shrinker->refcount, 1); + init_completion(&shrinker->completion_wait); list_add_tail(&shrinker->list, &shrinker_list); shrinker->flags |= SHRINKER_REGISTERED; shrinker_debugfs_add(shrinker); @@ -794,6 +796,9 @@ void unregister_shrinker(struct shrinker *shrinker) if (!(shrinker->flags & SHRINKER_REGISTERED)) return; + shrinker_put(shrinker); + wait_for_completion(&shrinker->completion_wait); + down_write(&shrinker_rwsem); list_del(&shrinker->list); shrinker->flags &= ~SHRINKER_REGISTERED; -- 2.30.2 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel