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Subject[PATCH 02/10] threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem
Date
Make the following renames to prepare for extension of threadgroup
locking.

* s/signal->threadgroup_fork_lock/signal->group_rwsem/
* s/threadgroup_fork_read_lock()/threadgroup_change_begin()/
* s/threadgroup_fork_read_unlock()/threadgroup_change_done()/
* s/threadgroup_fork_write_lock()/threadgroup_lock()/
* s/threadgroup_fork_write_unlock()/threadgroup_unlock()/

This patch doesn't cause any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
---
include/linux/init_task.h | 9 ++++-----
include/linux/sched.h | 30 +++++++++++++++---------------
kernel/cgroup.c | 13 ++++++-------
kernel/fork.c | 8 ++++----
4 files changed, 29 insertions(+), 31 deletions(-)
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 08ffab0..ef20cbe 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -23,11 +23,10 @@ extern struct files_struct init_files;
extern struct fs_struct init_fs;

#ifdef CONFIG_CGROUPS
-#define INIT_THREADGROUP_FORK_LOCK(sig) \
- .threadgroup_fork_lock = \
- __RWSEM_INITIALIZER(sig.threadgroup_fork_lock),
+#define INIT_GROUP_RWSEM(sig) \
+ .group_rwsem = __RWSEM_INITIALIZER(sig.group_rwsem),
#else
-#define INIT_THREADGROUP_FORK_LOCK(sig)
+#define INIT_GROUP_RWSEM(sig)
#endif

#define INIT_SIGNALS(sig) { \
@@ -46,7 +45,7 @@ extern struct fs_struct init_fs;
}, \
.cred_guard_mutex = \
__MUTEX_INITIALIZER(sig.cred_guard_mutex), \
- INIT_THREADGROUP_FORK_LOCK(sig) \
+ INIT_GROUP_RWSEM(sig) \
}

extern struct nsproxy init_nsproxy;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e8acce7..aa47d0f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -635,13 +635,13 @@ struct signal_struct {
#endif
#ifdef CONFIG_CGROUPS
/*
- * The threadgroup_fork_lock prevents threads from forking with
+ * The group_rwsem prevents threads from forking with
* CLONE_THREAD while held for writing. Use this for fork-sensitive
* threadgroup-wide operations. It's taken for reading in fork.c in
* copy_process().
* Currently only needed write-side by cgroups.
*/
- struct rw_semaphore threadgroup_fork_lock;
+ struct rw_semaphore group_rwsem;
#endif

int oom_adj; /* OOM kill score adjustment (bit shift) */
@@ -2367,29 +2367,29 @@ static inline void unlock_task_sighand(struct task_struct *tsk,
spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
}

-/* See the declaration of threadgroup_fork_lock in signal_struct. */
+/* See the declaration of group_rwsem in signal_struct. */
#ifdef CONFIG_CGROUPS
-static inline void threadgroup_fork_read_lock(struct task_struct *tsk)
+static inline void threadgroup_change_begin(struct task_struct *tsk)
{
- down_read(&tsk->signal->threadgroup_fork_lock);
+ down_read(&tsk->signal->group_rwsem);
}
-static inline void threadgroup_fork_read_unlock(struct task_struct *tsk)
+static inline void threadgroup_change_done(struct task_struct *tsk)
{
- up_read(&tsk->signal->threadgroup_fork_lock);
+ up_read(&tsk->signal->group_rwsem);
}
-static inline void threadgroup_fork_write_lock(struct task_struct *tsk)
+static inline void threadgroup_lock(struct task_struct *tsk)
{
- down_write(&tsk->signal->threadgroup_fork_lock);
+ down_write(&tsk->signal->group_rwsem);
}
-static inline void threadgroup_fork_write_unlock(struct task_struct *tsk)
+static inline void threadgroup_unlock(struct task_struct *tsk)
{
- up_write(&tsk->signal->threadgroup_fork_lock);
+ up_write(&tsk->signal->group_rwsem);
}
#else
-static inline void threadgroup_fork_read_lock(struct task_struct *tsk) {}
-static inline void threadgroup_fork_read_unlock(struct task_struct *tsk) {}
-static inline void threadgroup_fork_write_lock(struct task_struct *tsk) {}
-static inline void threadgroup_fork_write_unlock(struct task_struct *tsk) {}
+static inline void threadgroup_change_begin(struct task_struct *tsk) {}
+static inline void threadgroup_change_done(struct task_struct *tsk) {}
+static inline void threadgroup_lock(struct task_struct *tsk) {}
+static inline void threadgroup_unlock(struct task_struct *tsk) {}
#endif

#ifndef __HAVE_THREAD_FUNCTIONS
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index efa5886..f0e099f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2003,8 +2003,8 @@ static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg,
* @cgrp: the cgroup to attach to
* @leader: the threadgroup leader task_struct of the group to be attached
*
- * Call holding cgroup_mutex and the threadgroup_fork_lock of the leader. Will
- * take task_lock of each thread in leader's threadgroup individually in turn.
+ * Call holding cgroup_mutex and the group_rwsem of the leader. Will take
+ * task_lock of each thread in leader's threadgroup individually in turn.
*/
int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
{
@@ -2030,8 +2030,8 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
* step 0: in order to do expensive, possibly blocking operations for
* every thread, we cannot iterate the thread group list, since it needs
* rcu or tasklist locked. instead, build an array of all threads in the
- * group - threadgroup_fork_lock prevents new threads from appearing,
- * and if threads exit, this will just be an over-estimate.
+ * group - group_rwsem prevents new threads from appearing, and if
+ * threads exit, this will just be an over-estimate.
*/
group_size = get_nr_threads(leader);
/* flex_array supports very large thread-groups better than kmalloc. */
@@ -2246,7 +2246,6 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
cgroup_unlock();
return -ESRCH;
}
-
/*
* even if we're attaching all tasks in the thread group, we
* only need to check permissions on one of them.
@@ -2270,9 +2269,9 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
}

if (threadgroup) {
- threadgroup_fork_write_lock(tsk);
+ threadgroup_lock(tsk);
ret = cgroup_attach_proc(cgrp, tsk);
- threadgroup_fork_write_unlock(tsk);
+ threadgroup_unlock(tsk);
} else {
ret = cgroup_attach_task(cgrp, tsk);
}
diff --git a/kernel/fork.c b/kernel/fork.c
index 8e6b6f4..c2af839 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -980,7 +980,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
sched_autogroup_fork(sig);

#ifdef CONFIG_CGROUPS
- init_rwsem(&sig->threadgroup_fork_lock);
+ init_rwsem(&sig->group_rwsem);
#endif

sig->oom_adj = current->signal->oom_adj;
@@ -1166,7 +1166,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->io_context = NULL;
p->audit_context = NULL;
if (clone_flags & CLONE_THREAD)
- threadgroup_fork_read_lock(current);
+ threadgroup_change_begin(current);
cgroup_fork(p);
#ifdef CONFIG_NUMA
p->mempolicy = mpol_dup(p->mempolicy);
@@ -1378,7 +1378,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
proc_fork_connector(p);
cgroup_post_fork(p);
if (clone_flags & CLONE_THREAD)
- threadgroup_fork_read_unlock(current);
+ threadgroup_change_done(current);
perf_event_fork(p);
return p;

@@ -1418,7 +1418,7 @@ bad_fork_cleanup_policy:
bad_fork_cleanup_cgroup:
#endif
if (clone_flags & CLONE_THREAD)
- threadgroup_fork_read_unlock(current);
+ threadgroup_change_done(current);
cgroup_exit(p, cgroup_callbacks_done);
delayacct_tsk_free(p);
module_put(task_thread_info(p)->exec_domain->module);
--
1.7.3.1


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