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| author | Ben Blum <bblum@google.com> | 2009-09-23 15:56:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-24 07:20:58 -0700 |
| commit | c378369d8b4fa516ff2b1e79c3eded4e0e955ebb (patch) | |
| tree | 33dff6fa14c5b70cf25368b1bde57e5610a308b3 | |
| parent | d1d9fd3308fdef6b4bf564fa3d6cfe35b68b50bc (diff) | |
| download | blackbird-op-linux-c378369d8b4fa516ff2b1e79c3eded4e0e955ebb.tar.gz blackbird-op-linux-c378369d8b4fa516ff2b1e79c3eded4e0e955ebb.zip | |
cgroups: change css_set freeing mechanism to be under RCU
Changes css_set freeing mechanism to be under RCU
This is a prepatch for making the procs file writable. In order to free the
old css_sets for each task to be moved as they're being moved, the freeing
mechanism must be RCU-protected, or else we would have to have a call to
synchronize_rcu() for each task before freeing its old css_set.
Signed-off-by: Ben Blum <bblum@google.com>
Signed-off-by: Paul Menage <menage@google.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/cgroup.h | 3 | ||||
| -rw-r--r-- | kernel/cgroup.c | 8 |
2 files changed, 10 insertions, 1 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 88e863460726..3ac78a2f4b5a 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -260,6 +260,9 @@ struct css_set { * during subsystem registration (at boot time). */ struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; + + /* For RCU-protected deletion */ + struct rcu_head rcu_head; }; /* diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3e356b05b2d5..bf8dd1a9f2d1 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -267,6 +267,12 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) return &css_set_table[index]; } +static void free_css_set_rcu(struct rcu_head *obj) +{ + struct css_set *cg = container_of(obj, struct css_set, rcu_head); + kfree(cg); +} + /* We don't maintain the lists running through each css_set to its * task until after the first call to cgroup_iter_start(). This * reduces the fork()/exit() overhead for people who have cgroups @@ -310,7 +316,7 @@ static void __put_css_set(struct css_set *cg, int taskexit) } write_unlock(&css_set_lock); - kfree(cg); + call_rcu(&cg->rcu_head, free_css_set_rcu); } /* |
