From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 5/5] cgroup: remove cgroup_lock_is_held() Date: Thu, 4 Apr 2013 16:36:29 -0700 Message-ID: <1365118589-10619-6-git-send-email-tj@kernel.org> References: <1365118589-10619-1-git-send-email-tj@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:from:to:cc:subject:date:message-id:x-mailer :in-reply-to:references; bh=OIfkcz06V6KP5ChWiCtQ6TLrI/iCr0EXXTKr6L6kAWU=; b=CzFjoLLziDW3+rQiOBVxHOgukIp9hSzwVPTmfSaZKQWXGuCebvCjTQNckj9uX2aQmb an4iYQNoxk9gAONfB0SslniNeaGy7TAtTEDFiDc4paU0XY0pzrHDgr7pKn2AU5lh8PIK vp2E3MVCauU/wzcm87gJ23qsP3Thn+KE2QS4xLaClAzyt7+wElyRZtksf4MfYMarGOxr rudvpbWZK1gyp8OM8zPZU1Ibuv44A1UqATHZj6J9O7HjPjTQDmif7VIlAht0ABKfsmGg zoArj5wHYkxwHVjsdC927BbqznzjR0EbVwk/oaC+XXRWfjsGgI0pHe+tU9BAJlMserPL Fojw== In-Reply-To: <1365118589-10619-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org Cc: Tejun Heo , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org We don't want controllers to assume that the information is officially available and do funky things with it. The only user is task_subsys_state_check() which uses it to verify RCU access context. We can move cgroup_lock_is_held() inside CONFIG_PROVE_RCU but that doesn't add meaningful protection compared to conditionally exposing cgroup_mutex. Remove cgroup_lock_is_held(), export cgroup_mutex iff CONFIG_PROVE_RCU and use lockdep_is_held() directly on the mutex in task_subsys_state_check(). While at it, add parentheses around macro arguments in task_subsys_state_check(). Signed-off-by: Tejun Heo --- include/linux/cgroup.h | 13 +++++++++---- kernel/cgroup.c | 20 ++++++-------------- 2 files changed, 15 insertions(+), 18 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 63deb70..515927e 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -30,7 +30,6 @@ struct css_id; extern int cgroup_init_early(void); extern int cgroup_init(void); -extern int cgroup_lock_is_held(void); extern void cgroup_fork(struct task_struct *p); extern void cgroup_post_fork(struct task_struct *p); extern void cgroup_exit(struct task_struct *p, int run_callbacks); @@ -552,10 +551,16 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state( * rcu_dereference_check() conditions, such as locks used during the * cgroup_subsys::attach() methods. */ +#ifdef CONFIG_PROVE_RCU +extern struct mutex cgroup_mutex; #define task_subsys_state_check(task, subsys_id, __c) \ - rcu_dereference_check(task->cgroups->subsys[subsys_id], \ - lockdep_is_held(&task->alloc_lock) || \ - cgroup_lock_is_held() || (__c)) + rcu_dereference_check((task)->cgroups->subsys[(subsys_id)], \ + lockdep_is_held(&(task)->alloc_lock) || \ + lockdep_is_held(&cgroup_mutex) || (__c)) +#else +#define task_subsys_state_check(task, subsys_id, __c) \ + rcu_dereference((task)->cgroups->subsys[(subsys_id)]) +#endif static inline struct cgroup_subsys_state * task_subsys_state(struct task_struct *task, int subsys_id) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 1a65958..ba3e24a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -83,7 +83,13 @@ * B happens only through cgroup_show_options() and using cgroup_root_mutex * breaks it. */ +#ifdef CONFIG_PROVE_RCU +DEFINE_MUTEX(cgroup_mutex); +EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */ +#else static DEFINE_MUTEX(cgroup_mutex); +#endif + static DEFINE_MUTEX(cgroup_root_mutex); /* @@ -251,20 +257,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp); static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, struct cftype cfts[], bool is_add); -#ifdef CONFIG_PROVE_LOCKING -int cgroup_lock_is_held(void) -{ - return lockdep_is_held(&cgroup_mutex); -} -#else /* #ifdef CONFIG_PROVE_LOCKING */ -int cgroup_lock_is_held(void) -{ - return mutex_is_locked(&cgroup_mutex); -} -#endif /* #else #ifdef CONFIG_PROVE_LOCKING */ - -EXPORT_SYMBOL_GPL(cgroup_lock_is_held); - static int css_unbias_refcnt(int refcnt) { return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; -- 1.8.1.4