From 4fca88c87b7969c698912e2de9b1b31088c777cb Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Thu, 7 Feb 2008 00:14:27 -0800 Subject: [PATCH] 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 --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 87479328d4..d8e92223a7 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -233,6 +233,7 @@ int cgroup_is_descendant(const struct cgroup *cont); struct cgroup_subsys { struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss, struct cgroup *cont); + void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cont); void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cont); int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cont, struct task_struct *tsk); diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4d67a39c58..4e8b16a826 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); -- 2.39.5