Messages in this thread Patch in this message | | | Date | Thu, 15 Jan 2009 19:27:12 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | [PATCH 2/4] cgroup:add css_is_populated |
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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
cgroup creation is done in several stages. After allocated and linked to cgroup's hierarchy tree, all necessary control files are created.
When using CSS_ID, scanning cgroups without cgrouo_lock(), status of cgroup is important. At removal of cgroup/css, css_tryget() works fine and we can write a safe code. At creation, we need some flag to show "This cgroup is not ready yet"
This patch adds CSS_POPULATED flag.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
--- Index: mmotm-2.6.29-Jan14/include/linux/cgroup.h =================================================================== --- mmotm-2.6.29-Jan14.orig/include/linux/cgroup.h +++ mmotm-2.6.29-Jan14/include/linux/cgroup.h @@ -69,6 +69,7 @@ struct cgroup_subsys_state { enum { CSS_ROOT, /* This CSS is the root of the subsystem */ CSS_REMOVED, /* This CSS is dead */ + CSS_POPULATED, /* This CSS finished all initialization */ }; /* @@ -90,6 +91,11 @@ static inline bool css_is_removed(struct return test_bit(CSS_REMOVED, &css->flags); } +static inline bool css_is_populated(struct cgroup_subsys_state *css) +{ + return test_bit(CSS_POPULATED, &css->flags); +} + /* * Call css_tryget() to take a reference on a css if your existing * (known-valid) reference isn't already ref-counted. Returns false if Index: mmotm-2.6.29-Jan14/kernel/cgroup.c =================================================================== --- mmotm-2.6.29-Jan14.orig/kernel/cgroup.c +++ mmotm-2.6.29-Jan14/kernel/cgroup.c @@ -2326,8 +2326,10 @@ static int cgroup_populate_dir(struct cg } for_each_subsys(cgrp->root, ss) { + struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) return err; + set_bit(CSS_POPULATED, &css->flags); } return 0;
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