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authorLinus Torvalds <torvalds@linux-foundation.org>2017-06-05 15:37:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-06-05 15:37:03 -0700
commitba7b2387ad239a519041f2a2d35a1902bdd03dfb (patch)
tree76d562693c551a38d1d096fe598f8b9612366256 /include
parente543c8a92fb6eca8dd554561fa55bba5f2a90d09 (diff)
parent41c25707d21716826e3c1f60967f5550610ec1c9 (diff)
Merge branch 'for-4.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo: "Two cgroup fixes. One to address RCU delay of cpuset removal affecting userland visible behaviors. The other fixes a race condition between controller disable and cgroup removal" * 'for-4.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cpuset: consider dying css as offline cgroup: Prevent kill_css() from being called more than once
Diffstat (limited to 'include')
-rw-r--r--include/linux/cgroup-defs.h1
-rw-r--r--include/linux/cgroup.h20
2 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 21745946cae1..ec47101cb1bf 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -48,6 +48,7 @@ enum {
CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
CSS_VISIBLE = (1 << 3), /* css is visible to userland */
+ CSS_DYING = (1 << 4), /* css is dying */
};
/* bits in struct cgroup flags field */
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index ed2573e149fa..710a005c6b7a 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -344,6 +344,26 @@ static inline bool css_tryget_online(struct cgroup_subsys_state *css)
}
/**
+ * css_is_dying - test whether the specified css is dying
+ * @css: target css
+ *
+ * Test whether @css is in the process of offlining or already offline. In
+ * most cases, ->css_online() and ->css_offline() callbacks should be
+ * enough; however, the actual offline operations are RCU delayed and this
+ * test returns %true also when @css is scheduled to be offlined.
+ *
+ * This is useful, for example, when the use case requires synchronous
+ * behavior with respect to cgroup removal. cgroup removal schedules css
+ * offlining but the css can seem alive while the operation is being
+ * delayed. If the delay affects user visible semantics, this test can be
+ * used to resolve the situation.
+ */
+static inline bool css_is_dying(struct cgroup_subsys_state *css)
+{
+ return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);
+}
+
+/**
* css_put - put a css reference
* @css: target css
*