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authorLinus Torvalds2012-01-09 12:59:24 -0800
committerLinus Torvalds2012-01-09 12:59:24 -0800
commitdb0c2bf69aa095d4a6de7b1145f29fe9a7c0f6a3 (patch)
tree8f38957c01b18edddd44d49ecc3beeac08a20b4e /include
parentac69e0928054ff29a5049902fb477f9c7605c773 (diff)
parent0d19ea866562e46989412a0676412fa0983c9ce7 (diff)
Merge branch 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
* 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits) cgroup: fix to allow mounting a hierarchy by name cgroup: move assignement out of condition in cgroup_attach_proc() cgroup: Remove task_lock() from cgroup_post_fork() cgroup: add sparse annotation to cgroup_iter_start() and cgroup_iter_end() cgroup: mark cgroup_rmdir_waitq and cgroup_attach_proc() as static cgroup: only need to check oldcgrp==newgrp once cgroup: remove redundant get/put of task struct cgroup: remove redundant get/put of old css_set from migrate cgroup: Remove unnecessary task_lock before fetching css_set on migration cgroup: Drop task_lock(parent) on cgroup_fork() cgroups: remove redundant get/put of css_set from css_set_check_fetched() resource cgroups: remove bogus cast cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() cgroup, cpuset: don't use ss->pre_attach() cgroup: don't use subsys->can_attach_task() or ->attach_task() cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach() cgroup: improve old cgroup handling in cgroup_attach_proc() cgroup: always lock threadgroup during migration threadgroup: extend threadgroup_lock() to cover exit and exec threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem ... Fix up conflict in kernel/cgroup.c due to commit e0197aae59e5: "cgroups: fix a css_set not found bug in cgroup_attach_proc" that already mentioned that the bug is fixed (differently) in Tejun's cgroup patchset. This one, in other words.
Diffstat (limited to 'include')
-rw-r--r--include/linux/cgroup.h31
-rw-r--r--include/linux/init_task.h9
-rw-r--r--include/linux/sched.h73
3 files changed, 83 insertions, 30 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a17becc36ca1..e9b602151caf 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -457,6 +457,28 @@ void cgroup_exclude_rmdir(struct cgroup_subsys_state *css);
void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css);
/*
+ * Control Group taskset, used to pass around set of tasks to cgroup_subsys
+ * methods.
+ */
+struct cgroup_taskset;
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
+struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset);
+int cgroup_taskset_size(struct cgroup_taskset *tset);
+
+/**
+ * cgroup_taskset_for_each - iterate cgroup_taskset
+ * @task: the loop cursor
+ * @skip_cgrp: skip if task's cgroup matches this, %NULL to iterate through all
+ * @tset: taskset to iterate
+ */
+#define cgroup_taskset_for_each(task, skip_cgrp, tset) \
+ for ((task) = cgroup_taskset_first((tset)); (task); \
+ (task) = cgroup_taskset_next((tset))) \
+ if (!(skip_cgrp) || \
+ cgroup_taskset_cur_cgroup((tset)) != (skip_cgrp))
+
+/*
* Control Group subsystem type.
* See Documentation/cgroups/cgroups.txt for details
*/
@@ -467,14 +489,11 @@ struct cgroup_subsys {
int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct task_struct *tsk);
- int (*can_attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
+ struct cgroup_taskset *tset);
void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct task_struct *tsk);
- void (*pre_attach)(struct cgroup *cgrp);
- void (*attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
+ struct cgroup_taskset *tset);
void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup *old_cgrp, struct task_struct *tsk);
+ struct cgroup_taskset *tset);
void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
void (*exit)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup *old_cgrp, struct task_struct *task);
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 32574eef9394..9c66b1ada9d7 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 ad93e1ec8c65..f044f66018f2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -637,13 +637,15 @@ struct signal_struct {
#endif
#ifdef CONFIG_CGROUPS
/*
- * The threadgroup_fork_lock 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.
+ * group_rwsem prevents new tasks from entering the threadgroup and
+ * member tasks from exiting,a more specifically, setting of
+ * PF_EXITING. fork and exit paths are protected with this rwsem
+ * using threadgroup_change_begin/end(). Users which require
+ * threadgroup to remain stable should use threadgroup_[un]lock()
+ * which also takes care of exec path. Currently, cgroup is the
+ * only user.
*/
- struct rw_semaphore threadgroup_fork_lock;
+ struct rw_semaphore group_rwsem;
#endif
int oom_adj; /* OOM kill score adjustment (bit shift) */
@@ -2394,29 +2396,62 @@ 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. */
#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_end(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)
+
+/**
+ * threadgroup_lock - lock threadgroup
+ * @tsk: member task of the threadgroup to lock
+ *
+ * Lock the threadgroup @tsk belongs to. No new task is allowed to enter
+ * and member tasks aren't allowed to exit (as indicated by PF_EXITING) or
+ * perform exec. This is useful for cases where the threadgroup needs to
+ * stay stable across blockable operations.
+ *
+ * fork and exit paths explicitly call threadgroup_change_{begin|end}() for
+ * synchronization. While held, no new task will be added to threadgroup
+ * and no existing live task will have its PF_EXITING set.
+ *
+ * During exec, a task goes and puts its thread group through unusual
+ * changes. After de-threading, exclusive access is assumed to resources
+ * which are usually shared by tasks in the same group - e.g. sighand may
+ * be replaced with a new one. Also, the exec'ing task takes over group
+ * leader role including its pid. Exclude these changes while locked by
+ * grabbing cred_guard_mutex which is used to synchronize exec path.
+ */
+static inline void threadgroup_lock(struct task_struct *tsk)
{
- down_write(&tsk->signal->threadgroup_fork_lock);
+ /*
+ * exec uses exit for de-threading nesting group_rwsem inside
+ * cred_guard_mutex. Grab cred_guard_mutex first.
+ */
+ mutex_lock(&tsk->signal->cred_guard_mutex);
+ down_write(&tsk->signal->group_rwsem);
}
-static inline void threadgroup_fork_write_unlock(struct task_struct *tsk)
+
+/**
+ * threadgroup_unlock - unlock threadgroup
+ * @tsk: member task of the threadgroup to unlock
+ *
+ * Reverse threadgroup_lock().
+ */
+static inline void threadgroup_unlock(struct task_struct *tsk)
{
- up_write(&tsk->signal->threadgroup_fork_lock);
+ up_write(&tsk->signal->group_rwsem);
+ mutex_unlock(&tsk->signal->cred_guard_mutex);
}
#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_end(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