diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-06-05 15:37:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-06-05 15:37:03 -0700 |
| commit | ba7b2387ad239a519041f2a2d35a1902bdd03dfb (patch) | |
| tree | 76d562693c551a38d1d096fe598f8b9612366256 /include | |
| parent | e543c8a92fb6eca8dd554561fa55bba5f2a90d09 (diff) | |
| parent | 41c25707d21716826e3c1f60967f5550610ec1c9 (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.h | 1 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 20 |
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 * |