linux-kernel - [PATCH RFC 04/10] mm: Split unregister

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 07 Aug 2018 18:38:12 +0300
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     akpm@...ux-foundation.org, gregkh@...uxfoundation.org,
        rafael@...nel.org, viro@...iv.linux.org.uk,
        darrick.wong@...cle.com, paulmck@...ux.vnet.ibm.com,
        josh@...htriplett.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com,
        hughd@...gle.com, shuah@...nel.org, robh@...nel.org,
        ulf.hansson@...aro.org, aspriel@...il.com,
        vivek.gautam@...eaurora.org, robin.murphy@....com, joe@...ches.com,
        heikki.krogerus@...ux.intel.com, ktkhai@...tuozzo.com,
        sfr@...b.auug.org.au, vdavydov.dev@...il.com, mhocko@...e.com,
        chris@...is-wilson.co.uk, penguin-kernel@...ove.SAKURA.ne.jp,
        aryabinin@...tuozzo.com, willy@...radead.org, ying.huang@...el.com,
        shakeelb@...gle.com, jbacik@...com, mingo@...nel.org,
        mhiramat@...nel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH RFC 04/10] mm: Split unregister_shrinker()

This and the next patches in this series aim to make
time effect of synchronize_srcu() invisible for user.
The patch splits unregister_shrinker() in two functions:

	unregister_shrinker_delayed_initiate()
	unregister_shrinker_delayed_finalize()

and shrinker users may make the second of them to be called
asynchronous (e.g., from workqueue). Next patches make
superblock shrinker to follow this way, so user-visible
umount() time won't contain delays from synchronize_srcu().

Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
---
 include/linux/shrinker.h |    2 ++
 mm/vmscan.c              |   22 ++++++++++++++++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 9443cafd1969..92062d1239c2 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -86,5 +86,7 @@ extern int prealloc_shrinker(struct shrinker *shrinker);
 extern void register_shrinker_prepared(struct shrinker *shrinker);
 extern int register_shrinker(struct shrinker *shrinker);
 extern void unregister_shrinker(struct shrinker *shrinker);
+extern void unregister_shrinker_delayed_initiate(struct shrinker *shrinker);
+extern void unregister_shrinker_delayed_finalize(struct shrinker *shrinker);
 extern void free_prealloced_shrinker(struct shrinker *shrinker);
 #endif
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2dc274a385b9..fba4996dfe25 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -422,10 +422,7 @@ int register_shrinker(struct shrinker *shrinker)
 }
 EXPORT_SYMBOL(register_shrinker);
 
-/*
- * Remove one
- */
-void unregister_shrinker(struct shrinker *shrinker)
+void unregister_shrinker_delayed_initiate(struct shrinker *shrinker)
 {
 	if (!shrinker->nr_deferred)
 		return;
@@ -434,12 +431,29 @@ void unregister_shrinker(struct shrinker *shrinker)
 	mutex_lock(&shrinker_mutex);
 	list_del_rcu(&shrinker->list);
 	mutex_unlock(&shrinker_mutex);
+}
+EXPORT_SYMBOL(unregister_shrinker_delayed_initiate);
+
+void unregister_shrinker_delayed_finalize(struct shrinker *shrinker)
+{
+	if (!shrinker->nr_deferred)
+		return;
 
 	synchronize_srcu(&srcu);
 
 	kfree(shrinker->nr_deferred);
 	shrinker->nr_deferred = NULL;
 }
+EXPORT_SYMBOL(unregister_shrinker_delayed_finalize);
+
+/*
+ * Remove one
+ */
+void unregister_shrinker(struct shrinker *shrinker)
+{
+	unregister_shrinker_delayed_initiate(shrinker);
+	unregister_shrinker_delayed_finalize(shrinker);
+}
 EXPORT_SYMBOL(unregister_shrinker);
 
 #define SHRINK_BATCH 128