From 4fca88c87b7969c698912e2de9b1b31088c777cb Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Thu, 7 Feb 2008 00:14:27 -0800 Subject: memory cgroup enhancements: add- pre_destroy() handler Add a handler "pre_destroy" to cgroup_subsys. It is called before cgroup_rmdir() checks all subsys's refcnt. I think this is useful for subsys which have some extra refs even if there are no tasks in cgroup. By adding pre_destroy(), the kernel keeps the rule "destroy() against subsystem is called only when refcnt=0." and allows css ref to be used by other objects than tasks. Signed-off-by: KAMEZAWA Hiroyuki Cc: "Eric W. Biederman" Cc: Balbir Singh Cc: David Rientjes Cc: Herbert Poetzl Cc: Kirill Korotaev Cc: Nick Piggin Cc: Paul Menage Cc: Pavel Emelianov Cc: Peter Zijlstra Cc: Vaidyanathan Srinivasan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cgroup.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'kernel/cgroup.c') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4d67a39c58a8..4e8b16a8266c 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -586,6 +586,21 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb) return inode; } +/* + * Call subsys's pre_destroy handler. + * This is called before css refcnt check. + */ + +static void cgroup_call_pre_destroy(struct cgroup *cgrp) +{ + struct cgroup_subsys *ss; + for_each_subsys(cgrp->root, ss) + if (ss->pre_destroy && cgrp->subsys[ss->subsys_id]) + ss->pre_destroy(ss, cgrp); + return; +} + + static void cgroup_diput(struct dentry *dentry, struct inode *inode) { /* is dentry a directory ? if so, kfree() associated cgroup */ @@ -2160,6 +2175,13 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) parent = cgrp->parent; root = cgrp->root; sb = root->sb; + /* + * Call pre_destroy handlers of subsys + */ + cgroup_call_pre_destroy(cgrp); + /* + * Notify subsyses that rmdir() request comes. + */ if (cgroup_has_css_refs(cgrp)) { mutex_unlock(&cgroup_mutex); -- cgit v1.2.3