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Date: Fri, 11 Mar 2016 10:41:24 -0500
From: Tejun Heo <tj@...nel.org>
To: torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
a.p.zijlstra@...llo.nl, mingo@...hat.com, lizefan@...wei.com,
hannes@...xchg.org, pjt@...gle.com
Cc: linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
linux-api@...r.kernel.org, kernel-team@...com,
Tejun Heo <tj@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH 06/10] cgroup, fork: add @child and @clone_flags to threadgroup_change_begin/end()
When threadgroup_change_begin/end() are called from fork path, pass in
@child and @clone_flags so that fork path can be distinguished and
fork related information is available.
While at it, un-inline cgroup_threadgroup_change_begin/end() and fold
cgroup_fork() into cgroup_threadgroup_change_begin(). These changes
will be used to imlement in-process resource control.
Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Oleg Nesterov <oleg@...hat.com>
---
fs/exec.c | 6 +++---
include/linux/cgroup-defs.h | 39 ++++++++++++-------------------------
include/linux/cgroup.h | 2 --
include/linux/sched.h | 16 +++++++++++----
kernel/cgroup.c | 47 ++++++++++++++++++++++++++++++++++++---------
kernel/fork.c | 7 +++----
kernel/signal.c | 6 +++---
7 files changed, 71 insertions(+), 52 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 828ec5f..5b81bbb 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -936,7 +936,7 @@ static int de_thread(struct task_struct *tsk)
struct task_struct *leader = tsk->group_leader;
for (;;) {
- threadgroup_change_begin(tsk);
+ threadgroup_change_begin(tsk, NULL, 0);
write_lock_irq(&tasklist_lock);
/*
* Do this under tasklist_lock to ensure that
@@ -947,7 +947,7 @@ static int de_thread(struct task_struct *tsk)
break;
__set_current_state(TASK_KILLABLE);
write_unlock_irq(&tasklist_lock);
- threadgroup_change_end(tsk);
+ threadgroup_change_end(tsk, NULL, 0);
schedule();
if (unlikely(__fatal_signal_pending(tsk)))
goto killed;
@@ -1005,7 +1005,7 @@ static int de_thread(struct task_struct *tsk)
if (unlikely(leader->ptrace))
__wake_up_parent(leader, leader->parent);
write_unlock_irq(&tasklist_lock);
- threadgroup_change_end(tsk);
+ threadgroup_change_end(tsk, NULL, 0);
release_task(leader);
}
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index d3d1f92..3c4a75b 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -514,31 +514,12 @@ struct cgroup_subsys {
unsigned int depends_on;
};
-extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
-
-/**
- * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
- * @tsk: target task
- *
- * Called from threadgroup_change_begin() and allows cgroup operations to
- * synchronize against threadgroup changes using a percpu_rw_semaphore.
- */
-static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
-{
- percpu_down_read(&cgroup_threadgroup_rwsem);
-}
-
-/**
- * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
- * @tsk: target task
- *
- * Called from threadgroup_change_end(). Counterpart of
- * cgroup_threadcgroup_change_begin().
- */
-static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
-{
- percpu_up_read(&cgroup_threadgroup_rwsem);
-}
+void cgroup_threadgroup_change_begin(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags);
+void cgroup_threadgroup_change_end(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags);
#else /* CONFIG_CGROUPS */
@@ -546,8 +527,12 @@ struct css_set;
#define CGROUP_SUBSYS_COUNT 0
-static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
-static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
+static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags) {}
+static inline void cgroup_threadgroup_change_end(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags) {}
#endif /* CONFIG_CGROUPS */
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index ebcf21f..1e00fc0 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -101,7 +101,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *tsk);
-void cgroup_fork(struct task_struct *p);
extern int cgroup_can_fork(struct task_struct *p, unsigned long clone_flags,
struct css_set **new_rgrp_csetp);
extern void cgroup_cancel_fork(struct task_struct *p, unsigned long clone_flags,
@@ -540,7 +539,6 @@ static inline int cgroup_attach_task_all(struct task_struct *from,
static inline int cgroupstats_build(struct cgroupstats *stats,
struct dentry *dentry) { return -EINVAL; }
-static inline void cgroup_fork(struct task_struct *p) {}
static inline int cgroup_can_fork(struct task_struct *p,
unsigned long clone_flags,
struct css_set **new_rgrp_csetp) { return 0; }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 80d6ed1..d4ae795 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2783,6 +2783,8 @@ static inline void unlock_task_sighand(struct task_struct *tsk,
/**
* threadgroup_change_begin - mark the beginning of changes to a threadgroup
* @tsk: task causing the changes
+ * @child: child task if forking, NULL otherwise
+ * @clone_flags: clone flags if forking
*
* All operations which modify a threadgroup - a new thread joining the
* group, death of a member thread (the assertion of PF_EXITING) and
@@ -2791,21 +2793,27 @@ static inline void unlock_task_sighand(struct task_struct *tsk,
* subsystems needing threadgroup stability can hook into for
* synchronization.
*/
-static inline void threadgroup_change_begin(struct task_struct *tsk)
+static inline void threadgroup_change_begin(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags)
{
might_sleep();
- cgroup_threadgroup_change_begin(tsk);
+ cgroup_threadgroup_change_begin(tsk, child, clone_flags);
}
/**
* threadgroup_change_end - mark the end of changes to a threadgroup
* @tsk: task causing the changes
+ * @child: child task if forking, NULL otherwise
+ * @clone_flags: clone flags if forking
*
* See threadgroup_change_begin().
*/
-static inline void threadgroup_change_end(struct task_struct *tsk)
+static inline void threadgroup_change_end(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags)
{
- cgroup_threadgroup_change_end(tsk);
+ cgroup_threadgroup_change_end(tsk, child, clone_flags);
}
#ifndef __HAVE_THREAD_FUNCTIONS
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ac207ae..70f9985 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -110,7 +110,7 @@ static DEFINE_SPINLOCK(cgroup_file_kn_lock);
*/
static DEFINE_SPINLOCK(release_agent_path_lock);
-struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
+static struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
#define cgroup_assert_mutex_or_rcu_locked() \
RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
@@ -5688,17 +5688,46 @@ static const struct file_operations proc_cgroupstats_operations = {
};
/**
- * cgroup_fork - initialize cgroup related fields during copy_process()
- * @child: pointer to task_struct of forking parent process.
+ * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
+ * @tsk: target task
+ * @child: child task if forking, NULL otherwise
+ * @clone_flags: clone flags if forking
*
- * A task is associated with the init_css_set until cgroup_post_fork()
- * attaches it to the parent's css_set. Empty cg_list indicates that
- * @child isn't holding reference to its css_set.
+ * Called from threadgroup_change_begin() and allows cgroup operations to
+ * synchronize against threadgroup changes using a percpu_rw_semaphore.
*/
-void cgroup_fork(struct task_struct *child)
+void cgroup_threadgroup_change_begin(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags)
{
- RCU_INIT_POINTER(child->cgroups, &init_css_set);
- INIT_LIST_HEAD(&child->cg_list);
+ if (child) {
+ /*
+ * A task is associated with the init_css_set until
+ * cgroup_post_fork() attaches it to the parent's css_set.
+ * Empty cg_list indicates that @child isn't holding
+ * reference to its css_set.
+ */
+ RCU_INIT_POINTER(child->cgroups, &init_css_set);
+ INIT_LIST_HEAD(&child->cg_list);
+ }
+
+ percpu_down_read(&cgroup_threadgroup_rwsem);
+}
+
+/**
+ * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
+ * @tsk: target task
+ * @child: child task if forking, NULL otherwise
+ * @clone_flags: clone flags if forking
+ *
+ * Called from threadgroup_change_end(). Counterpart of
+ * cgroup_threadcgroup_change_begin().
+ */
+void cgroup_threadgroup_change_end(struct task_struct *tsk,
+ struct task_struct *child,
+ unsigned long clone_flags)
+{
+ percpu_up_read(&cgroup_threadgroup_rwsem);
}
/**
diff --git a/kernel/fork.c b/kernel/fork.c
index 812d477..840b662 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1368,8 +1368,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->real_start_time = ktime_get_boot_ns();
p->io_context = NULL;
p->audit_context = NULL;
- threadgroup_change_begin(current);
- cgroup_fork(p);
+ threadgroup_change_begin(current, p, clone_flags);
#ifdef CONFIG_NUMA
p->mempolicy = mpol_dup(p->mempolicy);
if (IS_ERR(p->mempolicy)) {
@@ -1609,7 +1608,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
proc_fork_connector(p);
cgroup_post_fork(p, clone_flags, new_rgrp_cset);
- threadgroup_change_end(current);
+ threadgroup_change_end(current, p, clone_flags);
perf_event_fork(p);
trace_task_newtask(p, clone_flags);
@@ -1650,7 +1649,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
mpol_put(p->mempolicy);
bad_fork_cleanup_threadgroup_lock:
#endif
- threadgroup_change_end(current);
+ threadgroup_change_end(current, p, clone_flags);
delayacct_tsk_free(p);
bad_fork_cleanup_count:
atomic_dec(&p->cred->user->processes);
diff --git a/kernel/signal.c b/kernel/signal.c
index f3f1f7a..1679c02 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2389,11 +2389,11 @@ void exit_signals(struct task_struct *tsk)
* @tsk is about to have PF_EXITING set - lock out users which
* expect stable threadgroup.
*/
- threadgroup_change_begin(tsk);
+ threadgroup_change_begin(tsk, NULL, 0);
if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
tsk->flags |= PF_EXITING;
- threadgroup_change_end(tsk);
+ threadgroup_change_end(tsk, NULL, 0);
return;
}
@@ -2404,7 +2404,7 @@ void exit_signals(struct task_struct *tsk)
*/
tsk->flags |= PF_EXITING;
- threadgroup_change_end(tsk);
+ threadgroup_change_end(tsk, NULL, 0);
if (!signal_pending(tsk))
goto out;
--
2.5.0
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