From 7d7efec368d537226142cbe559f45797f18672f9 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 13 May 2015 16:35:16 -0400 Subject: sched, cgroup: reorganize threadgroup locking threadgroup_change_begin/end() are used to mark the beginning and end of threadgroup modifying operations to allow code paths which require a threadgroup to stay stable across blocking operations to synchronize against those sections using threadgroup_lock/unlock(). It's currently implemented as a general mechanism in sched.h using per-signal_struct rwsem; however, this never grew non-cgroup use cases and becomes noop if !CONFIG_CGROUPS. It turns out that cgroups is gonna be better served with a different sycnrhonization scheme and is a bit silly to keep cgroups specific details as a general mechanism. What's general here is identifying the places where threadgroups are modified. This patch restructures threadgroup locking so that threadgroup_change_begin/end() become a place where subsystems which need to sycnhronize against threadgroup changes can hook into. cgroup_threadgroup_change_begin/end() which operate on the per-signal_struct rwsem are created and threadgroup_lock/unlock() are moved to cgroup.c and made static. This is pure reorganization which doesn't cause any functional changes. Signed-off-by: Tejun Heo Cc: Ingo Molnar Cc: Peter Zijlstra --- include/linux/cgroup-defs.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux/cgroup-defs.h') diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 55f3120fb952..1b8c93806dbd 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -14,6 +14,7 @@ #include #include #include +#include #include #ifdef CONFIG_CGROUPS @@ -460,5 +461,14 @@ struct cgroup_subsys { unsigned int depends_on; }; +void cgroup_threadgroup_change_begin(struct task_struct *tsk); +void cgroup_threadgroup_change_end(struct task_struct *tsk); + +#else /* CONFIG_CGROUPS */ + +static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {} +static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} + #endif /* CONFIG_CGROUPS */ + #endif /* _LINUX_CGROUP_DEFS_H */ -- cgit v1.2.3