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authorLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 18:11:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-20 18:11:21 -0700
commit0d9cabdccedb79ee5f27b77ff51f29a9e7d23275 (patch)
tree8bfb64c3672d058eb90aec3c3a9c4f61cef9097c /kernel
parent701085b219016d38f105b031381b9cee6200253a (diff)
parent3ce3230a0cff484e5130153f244d4fb8a56b3a8b (diff)
downloadop-kernel-dev-0d9cabdccedb79ee5f27b77ff51f29a9e7d23275.zip
op-kernel-dev-0d9cabdccedb79ee5f27b77ff51f29a9e7d23275.tar.gz
Merge branch 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup changes from Tejun Heo: "Out of the 8 commits, one fixes a long-standing locking issue around tasklist walking and others are cleanups." * 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list cgroup: Remove wrong comment on cgroup_enable_task_cg_list() cgroup: remove cgroup_subsys argument from callbacks cgroup: remove extra calls to find_existing_css_set cgroup: replace tasklist_lock with rcu_read_lock cgroup: simplify double-check locking in cgroup_attach_proc cgroup: move struct cgroup_pidlist out from the header file cgroup: remove cgroup_attach_task_current_cg()
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c327
-rw-r--r--kernel/cgroup_freezer.c11
-rw-r--r--kernel/cpuset.c16
-rw-r--r--kernel/events/core.c13
-rw-r--r--kernel/sched/core.c20
5 files changed, 158 insertions, 229 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a5d3b53..c6877fe 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -818,7 +818,7 @@ static int cgroup_call_pre_destroy(struct cgroup *cgrp)
for_each_subsys(cgrp->root, ss)
if (ss->pre_destroy) {
- ret = ss->pre_destroy(ss, cgrp);
+ ret = ss->pre_destroy(cgrp);
if (ret)
break;
}
@@ -846,7 +846,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
* Release the subsystem state objects.
*/
for_each_subsys(cgrp->root, ss)
- ss->destroy(ss, cgrp);
+ ss->destroy(cgrp);
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
@@ -1015,7 +1015,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
list_move(&ss->sibling, &root->subsys_list);
ss->root = root;
if (ss->bind)
- ss->bind(ss, cgrp);
+ ss->bind(cgrp);
mutex_unlock(&ss->hierarchy_mutex);
/* refcount was already taken, and we're keeping it */
} else if (bit & removed_bits) {
@@ -1025,7 +1025,7 @@ static int rebind_subsystems(struct cgroupfs_root *root,
BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
mutex_lock(&ss->hierarchy_mutex);
if (ss->bind)
- ss->bind(ss, dummytop);
+ ss->bind(dummytop);
dummytop->subsys[i]->cgroup = dummytop;
cgrp->subsys[i] = NULL;
subsys[i]->root = &rootnode;
@@ -1763,6 +1763,7 @@ EXPORT_SYMBOL_GPL(cgroup_path);
struct task_and_cgroup {
struct task_struct *task;
struct cgroup *cgrp;
+ struct css_set *cg;
};
struct cgroup_taskset {
@@ -1843,11 +1844,10 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size);
* will already exist. If not set, this function might sleep, and can fail with
* -ENOMEM. Must be called with cgroup_mutex and threadgroup locked.
*/
-static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
- struct task_struct *tsk, bool guarantee)
+static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
+ struct task_struct *tsk, struct css_set *newcg)
{
struct css_set *oldcg;
- struct css_set *newcg;
/*
* We are synchronized through threadgroup_lock() against PF_EXITING
@@ -1857,23 +1857,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
WARN_ON_ONCE(tsk->flags & PF_EXITING);
oldcg = tsk->cgroups;
- /* locate or allocate a new css_set for this task. */
- if (guarantee) {
- /* we know the css_set we want already exists. */
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(oldcg, cgrp, template);
- BUG_ON(!newcg);
- get_css_set(newcg);
- read_unlock(&css_set_lock);
- } else {
- might_sleep();
- /* find_css_set will give us newcg already referenced. */
- newcg = find_css_set(oldcg, cgrp);
- if (!newcg)
- return -ENOMEM;
- }
-
task_lock(tsk);
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
@@ -1892,7 +1875,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
put_css_set(oldcg);
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
- return 0;
}
/**
@@ -1910,6 +1892,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
struct cgroup *oldcgrp;
struct cgroupfs_root *root = cgrp->root;
struct cgroup_taskset tset = { };
+ struct css_set *newcg;
/* @tsk either already exited or can't exit until the end */
if (tsk->flags & PF_EXITING)
@@ -1925,7 +1908,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
for_each_subsys(root, ss) {
if (ss->can_attach) {
- retval = ss->can_attach(ss, cgrp, &tset);
+ retval = ss->can_attach(cgrp, &tset);
if (retval) {
/*
* Remember on which subsystem the can_attach()
@@ -1939,13 +1922,17 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
}
}
- retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, false);
- if (retval)
+ newcg = find_css_set(tsk->cgroups, cgrp);
+ if (!newcg) {
+ retval = -ENOMEM;
goto out;
+ }
+
+ cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg);
for_each_subsys(root, ss) {
if (ss->attach)
- ss->attach(ss, cgrp, &tset);
+ ss->attach(cgrp, &tset);
}
synchronize_rcu();
@@ -1967,7 +1954,7 @@ out:
*/
break;
if (ss->cancel_attach)
- ss->cancel_attach(ss, cgrp, &tset);
+ ss->cancel_attach(cgrp, &tset);
}
}
return retval;
@@ -1997,66 +1984,6 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-/*
- * cgroup_attach_proc works in two stages, the first of which prefetches all
- * new css_sets needed (to make sure we have enough memory before committing
- * to the move) and stores them in a list of entries of the following type.
- * TODO: possible optimization: use css_set->rcu_head for chaining instead
- */
-struct cg_list_entry {
- struct css_set *cg;
- struct list_head links;
-};
-
-static bool css_set_check_fetched(struct cgroup *cgrp,
- struct task_struct *tsk, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
-
- read_lock(&css_set_lock);
- newcg = find_existing_css_set(cg, cgrp, template);
- read_unlock(&css_set_lock);
-
- /* doesn't exist at all? */
- if (!newcg)
- return false;
- /* see if it's already in the list */
- list_for_each_entry(cg_entry, newcg_list, links)
- if (cg_entry->cg == newcg)
- return true;
-
- /* not found */
- return false;
-}
-
-/*
- * Find the new css_set and store it in the list in preparation for moving the
- * given task to the given cgroup. Returns 0 or -ENOMEM.
- */
-static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg,
- struct list_head *newcg_list)
-{
- struct css_set *newcg;
- struct cg_list_entry *cg_entry;
-
- /* ensure a new css_set will exist for this thread */
- newcg = find_css_set(cg, cgrp);
- if (!newcg)
- return -ENOMEM;
- /* add it to the list */
- cg_entry = kmalloc(sizeof(struct cg_list_entry), GFP_KERNEL);
- if (!cg_entry) {
- put_css_set(newcg);
- return -ENOMEM;
- }
- cg_entry->cg = newcg;
- list_add(&cg_entry->links, newcg_list);
- return 0;
-}
-
/**
* cgroup_attach_proc - attach all threads in a threadgroup to a cgroup
* @cgrp: the cgroup to attach to
@@ -2070,20 +1997,12 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
int retval, i, group_size;
struct cgroup_subsys *ss, *failed_ss = NULL;
/* guaranteed to be initialized later, but the compiler needs this */
- struct css_set *oldcg;
struct cgroupfs_root *root = cgrp->root;
/* threadgroup list cursor and array */
struct task_struct *tsk;
struct task_and_cgroup *tc;
struct flex_array *group;
struct cgroup_taskset tset = { };
- /*
- * we need to make sure we have css_sets for all the tasks we're
- * going to move -before- we actually start moving them, so that in
- * case we get an ENOMEM we can bail out before making any changes.
- */
- struct list_head newcg_list;
- struct cg_list_entry *cg_entry, *temp_nobe;
/*
* step 0: in order to do expensive, possibly blocking operations for
@@ -2102,23 +2021,14 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
if (retval)
goto out_free_group_list;
- /* prevent changes to the threadgroup list while we take a snapshot. */
- read_lock(&tasklist_lock);
- if (!thread_group_leader(leader)) {
- /*
- * a race with de_thread from another thread's exec() may strip
- * us of our leadership, making while_each_thread unsafe to use
- * on this task. if this happens, there is no choice but to
- * throw this task away and try again (from cgroup_procs_write);
- * this is "double-double-toil-and-trouble-check locking".
- */
- read_unlock(&tasklist_lock);
- retval = -EAGAIN;
- goto out_free_group_list;
- }
-
tsk = leader;
i = 0;
+ /*
+ * Prevent freeing of tasks while we take a snapshot. Tasks that are
+ * already PF_EXITING could be freed from underneath us unless we
+ * take an rcu_read_lock.
+ */
+ rcu_read_lock();
do {
struct task_and_cgroup ent;
@@ -2128,24 +2038,24 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
/* as per above, nr_threads may decrease, but not increase. */
BUG_ON(i >= group_size);
- /*
- * saying GFP_ATOMIC has no effect here because we did prealloc
- * earlier, but it's good form to communicate our expectations.
- */
ent.task = tsk;
ent.cgrp = task_cgroup_from_root(tsk, root);
/* nothing to do if this task is already in the cgroup */
if (ent.cgrp == cgrp)
continue;
+ /*
+ * saying GFP_ATOMIC has no effect here because we did prealloc
+ * earlier, but it's good form to communicate our expectations.
+ */
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
BUG_ON(retval != 0);
i++;
} while_each_thread(leader, tsk);
+ rcu_read_unlock();
/* remember the number of threads in the array for later. */
group_size = i;
tset.tc_array = group;
tset.tc_array_len = group_size;
- read_unlock(&tasklist_lock);
/* methods shouldn't be called if no task is actually migrating */
retval = 0;
@@ -2157,7 +2067,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
*/
for_each_subsys(root, ss) {
if (ss->can_attach) {
- retval = ss->can_attach(ss, cgrp, &tset);
+ retval = ss->can_attach(cgrp, &tset);
if (retval) {
failed_ss = ss;
goto out_cancel_attach;
@@ -2169,17 +2079,12 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
* step 2: make sure css_sets exist for all threads to be migrated.
* we use find_css_set, which allocates a new one if necessary.
*/
- INIT_LIST_HEAD(&newcg_list);
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- oldcg = tc->task->cgroups;
-
- /* if we don't already have it in the list get a new one */
- if (!css_set_check_fetched(cgrp, tc->task, oldcg,
- &newcg_list)) {
- retval = css_set_prefetch(cgrp, oldcg, &newcg_list);
- if (retval)
- goto out_list_teardown;
+ tc->cg = find_css_set(tc->task->cgroups, cgrp);
+ if (!tc->cg) {
+ retval = -ENOMEM;
+ goto out_put_css_set_refs;
}
}
@@ -2190,8 +2095,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
*/
for (i = 0; i < group_size; i++) {
tc = flex_array_get(group, i);
- retval = cgroup_task_migrate(cgrp, tc->cgrp, tc->task, true);
- BUG_ON(retval);
+ cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg);
}
/* nothing is sensitive to fork() after this point. */
@@ -2200,7 +2104,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
*/
for_each_subsys(root, ss) {
if (ss->attach)
- ss->attach(ss, cgrp, &tset);
+ ss->attach(cgrp, &tset);
}
/*
@@ -2209,21 +2113,22 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
synchronize_rcu();
cgroup_wakeup_rmdir_waiter(cgrp);
retval = 0;
-out_list_teardown:
- /* clean up the list of prefetched css_sets. */
- list_for_each_entry_safe(cg_entry, temp_nobe, &newcg_list, links) {
- list_del(&cg_entry->links);
- put_css_set(cg_entry->cg);
- kfree(cg_entry);
+out_put_css_set_refs:
+ if (retval) {
+ for (i = 0; i < group_size; i++) {
+ tc = flex_array_get(group, i);
+ if (!tc->cg)
+ break;
+ put_css_set(tc->cg);
+ }
}
out_cancel_attach:
- /* same deal as in cgroup_attach_task */
if (retval) {
for_each_subsys(root, ss) {
if (ss == failed_ss)
break;
if (ss->cancel_attach)
- ss->cancel_attach(ss, cgrp, &tset);
+ ss->cancel_attach(cgrp, &tset);
}
}
out_free_group_list:
@@ -2245,22 +2150,14 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
+retry_find_task:
+ rcu_read_lock();
if (pid) {
- rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (!tsk) {
rcu_read_unlock();
- cgroup_unlock();
- return -ESRCH;
- }
- if (threadgroup) {
- /*
- * RCU protects this access, since tsk was found in the
- * tid map. a race with de_thread may cause group_leader
- * to stop being the leader, but cgroup_attach_proc will
- * detect it later.
- */
- tsk = tsk->group_leader;
+ ret= -ESRCH;
+ goto out_unlock_cgroup;
}
/*
* even if we're attaching all tasks in the thread group, we
@@ -2271,29 +2168,38 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
cred->euid != tcred->uid &&
cred->euid != tcred->suid) {
rcu_read_unlock();
- cgroup_unlock();
- return -EACCES;
+ ret = -EACCES;
+ goto out_unlock_cgroup;
}
- get_task_struct(tsk);
- rcu_read_unlock();
- } else {
- if (threadgroup)
- tsk = current->group_leader;
- else
- tsk = current;
- get_task_struct(tsk);
- }
-
- threadgroup_lock(tsk);
+ } else
+ tsk = current;
if (threadgroup)
+ tsk = tsk->group_leader;
+ get_task_struct(tsk);
+ rcu_read_unlock();
+
+ threadgroup_lock(tsk);
+ if (threadgroup) {
+ if (!thread_group_leader(tsk)) {
+ /*
+ * a race with de_thread from another thread's exec()
+ * may strip us of our leadership, if this happens,
+ * there is no choice but to throw this task away and
+ * try again; this is
+ * "double-double-toil-and-trouble-check locking".
+ */
+ threadgroup_unlock(tsk);
+ put_task_struct(tsk);
+ goto retry_find_task;
+ }
ret = cgroup_attach_proc(cgrp, tsk);
- else
+ } else
ret = cgroup_attach_task(cgrp, tsk);
-
threadgroup_unlock(tsk);
put_task_struct(tsk);
+out_unlock_cgroup:
cgroup_unlock();
return ret;
}
@@ -2305,16 +2211,7 @@ static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid)
static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid)
{
- int ret;
- do {
- /*
- * attach_proc fails with -EAGAIN if threadgroup leadership
- * changes in the middle of the operation, in which case we need
- * to find the task_struct for the new leader and start over.
- */
- ret = attach_task_by_pid(cgrp, tgid, true);
- } while (ret == -EAGAIN);
- return ret;
+ return attach_task_by_pid(cgrp, tgid, true);
}
/**
@@ -2804,15 +2701,20 @@ static void cgroup_advance_iter(struct cgroup *cgrp,
* using their cgroups capability, we don't maintain the lists running
* through each css_set to its tasks until we see the list actually
* used - in other words after the first call to cgroup_iter_start().
- *
- * The tasklist_lock is not held here, as do_each_thread() and
- * while_each_thread() are protected by RCU.
*/
static void cgroup_enable_task_cg_lists(void)
{
struct task_struct *p, *g;
write_lock(&css_set_lock);
use_task_css_set_links = 1;
+ /*
+ * We need tasklist_lock because RCU is not safe against
+ * while_each_thread(). Besides, a forking task that has passed
+ * cgroup_post_fork() without seeing use_task_css_set_links = 1
+ * is not guaranteed to have its child immediately visible in the
+ * tasklist if we walk through it with RCU.
+ */
+ read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
/*
@@ -2824,6 +2726,7 @@ static void cgroup_enable_task_cg_lists(void)
list_add(&p->cg_list, &p->cgroups->tasks);
task_unlock(p);
} while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
write_unlock(&css_set_lock);
}
@@ -3043,6 +2946,38 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan)
*
*/
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+ CGROUP_FILE_PROCS,
+ CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+ /*
+ * used to find which pidlist is wanted. doesn't change as long as
+ * this particular list stays in the list.
+ */
+ struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+ /* array of xids */
+ pid_t *list;
+ /* how many elements the above list has */
+ int length;
+ /* how many files are using the current array */
+ int use_count;
+ /* each of these stored in a list by its cgroup */
+ struct list_head links;
+ /* pointer to the cgroup we belong to, for list removal purposes */
+ struct cgroup *owner;
+ /* protects the other fields */
+ struct rw_semaphore mutex;
+};
+
/*
* The following two functions "fix" the issue where there are more pids
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
@@ -3827,7 +3762,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
set_bit(CGRP_CLONE_CHILDREN, &cgrp->flags);
for_each_subsys(root, ss) {
- struct cgroup_subsys_state *css = ss->create(ss, cgrp);
+ struct cgroup_subsys_state *css = ss->create(cgrp);
if (IS_ERR(css)) {
err = PTR_ERR(css);
@@ -3841,7 +3776,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
}
/* At error, ->destroy() callback has to free assigned ID. */
if (clone_children(parent) && ss->post_clone)
- ss->post_clone(ss, cgrp);
+ ss->post_clone(cgrp);
}
cgroup_lock_hierarchy(root);
@@ -3875,7 +3810,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
for_each_subsys(root, ss) {
if (cgrp->subsys[ss->subsys_id])
- ss->destroy(ss, cgrp);
+ ss->destroy(cgrp);
}
mutex_unlock(&cgroup_mutex);
@@ -4099,7 +4034,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
/* Create the top cgroup state for this subsystem */
list_add(&ss->sibling, &rootnode.subsys_list);
ss->root = &rootnode;
- css = ss->create(ss, dummytop);
+ css = ss->create(dummytop);
/* We don't handle early failures gracefully */
BUG_ON(IS_ERR(css));
init_cgroup_css(css, ss, dummytop);
@@ -4188,7 +4123,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
* no ss->create seems to need anything important in the ss struct, so
* this can happen first (i.e. before the rootnode attachment).
*/
- css = ss->create(ss, dummytop);
+ css = ss->create(dummytop);
if (IS_ERR(css)) {
/* failure case - need to deassign the subsys[] slot. */
subsys[i] = NULL;
@@ -4206,7 +4141,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
int ret = cgroup_init_idr(ss, css);
if (ret) {
dummytop->subsys[ss->subsys_id] = NULL;
- ss->destroy(ss, dummytop);
+ ss->destroy(dummytop);
subsys[i] = NULL;
mutex_unlock(&cgroup_mutex);
return ret;
@@ -4304,7 +4239,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
* pointer to find their state. note that this also takes care of
* freeing the css_id.
*/
- ss->destroy(ss, dummytop);
+ ss->destroy(dummytop);
dummytop->subsys[ss->subsys_id] = NULL;
mutex_unlock(&cgroup_mutex);
@@ -4580,7 +4515,7 @@ void cgroup_fork_callbacks(struct task_struct *child)
for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
if (ss->fork)
- ss->fork(ss, child);
+ ss->fork(child);
}
}
}
@@ -4596,6 +4531,17 @@ void cgroup_fork_callbacks(struct task_struct *child)
*/
void cgroup_post_fork(struct task_struct *child)
{
+ /*
+ * use_task_css_set_links is set to 1 before we walk the tasklist
+ * under the tasklist_lock and we read it here after we added the child
+ * to the tasklist under the tasklist_lock as well. If the child wasn't
+ * yet in the tasklist when we walked through it from
+ * cgroup_enable_task_cg_lists(), then use_task_css_set_links value
+ * should be visible now due to the paired locking and barriers implied
+ * by LOCK/UNLOCK: it is written before the tasklist_lock unlock
+ * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock
+ * lock on fork.
+ */
if (use_task_css_set_links) {
write_lock(&css_set_lock);
if (list_empty(&child->cg_list)) {
@@ -4682,7 +4628,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
struct cgroup *old_cgrp =
rcu_dereference_raw(cg->subsys[i])->cgroup;
struct cgroup *cgrp = task_cgroup(tsk, i);
- ss->exit(ss, cgrp, old_cgrp, tsk);
+ ss->exit(cgrp, old_cgrp, tsk);
}
}
}
@@ -5137,8 +5083,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)
}
#ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
- struct cgroup *cont)
+static struct cgroup_subsys_state *debug_create(struct cgroup *cont)
{
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
@@ -5148,7 +5093,7 @@ static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
return css;
}
-static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+static void debug_destroy(struct cgroup *cont)
{
kfree(cont->subsys[debug_subsys_id]);
}
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index fc0646b..f86e939 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -128,8 +128,7 @@ struct cgroup_subsys freezer_subsys;
* task->alloc_lock (inside __thaw_task(), prevents race with refrigerator())
* sighand->siglock
*/
-static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
- struct cgroup *cgroup)
+static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
{
struct freezer *freezer;
@@ -142,8 +141,7 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
return &freezer->css;
}
-static void freezer_destroy(struct cgroup_subsys *ss,
- struct cgroup *cgroup)
+static void freezer_destroy(struct cgroup *cgroup)
{
struct freezer *freezer = cgroup_freezer(cgroup);
@@ -164,8 +162,7 @@ static bool is_task_frozen_enough(struct task_struct *task)
* a write to that file racing against an attach, and hence the
* can_attach() result will remain valid until the attach completes.
*/
-static int freezer_can_attach(struct cgroup_subsys *ss,
- struct cgroup *new_cgroup,
+static int freezer_can_attach(struct cgroup *new_cgroup,
struct cgroup_taskset *tset)
{
struct freezer *freezer;
@@ -185,7 +182,7 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
return 0;
}
-static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
+static void freezer_fork(struct task_struct *task)
{
struct freezer *freezer;
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index a09ac2b..5d57583 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1399,8 +1399,7 @@ static nodemask_t cpuset_attach_nodemask_from;
static nodemask_t cpuset_attach_nodemask_to;
/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
-static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup_taskset *tset)
+static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct cpuset *cs = cgroup_cs(cgrp);
struct task_struct *task;
@@ -1436,8 +1435,7 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
return 0;
}
-static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup_taskset *tset)
+static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct mm_struct *mm;
struct task_struct *task;
@@ -1833,8 +1831,7 @@ static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
* (and likewise for mems) to the new cgroup. Called with cgroup_mutex
* held.
*/
-static void cpuset_post_clone(struct cgroup_subsys *ss,
- struct cgroup *cgroup)
+static void cpuset_post_clone(struct cgroup *cgroup)
{
struct cgroup *parent, *child;
struct cpuset *cs, *parent_cs;
@@ -1857,13 +1854,10 @@ static void cpuset_post_clone(struct cgroup_subsys *ss,
/*
* cpuset_create - create a cpuset
- * ss: cpuset cgroup subsystem
* cont: control group that the new cpuset will be part of
*/
-static struct cgroup_subsys_state *cpuset_create(
- struct cgroup_subsys *ss,
- struct cgroup *cont)
+static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
{
struct cpuset *cs;
struct cpuset *parent;
@@ -1902,7 +1896,7 @@ static struct cgroup_subsys_state *cpuset_create(
* will call async_rebuild_sched_domains().
*/
-static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+static void cpuset_destroy(struct cgroup *cont)
{
struct cpuset *cs = cgroup_cs(cont);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c61234b..4b50357 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7147,8 +7147,7 @@ unlock:
device_initcall(perf_event_sysfs_init);
#ifdef CONFIG_CGROUP_PERF
-static struct cgroup_subsys_state *perf_cgroup_create(
- struct cgroup_subsys *ss, struct cgroup *cont)
+static struct cgroup_subsys_state *perf_cgroup_create(struct cgroup *cont)
{
struct perf_cgroup *jc;
@@ -7165,8 +7164,7 @@ static struct cgroup_subsys_state *perf_cgroup_create(
return &jc->css;
}
-static void perf_cgroup_destroy(struct cgroup_subsys *ss,
- struct cgroup *cont)
+static void perf_cgroup_destroy(struct cgroup *cont)
{
struct perf_cgroup *jc;
jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
@@ -7182,8 +7180,7 @@ static int __perf_cgroup_move(void *info)
return 0;
}
-static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup_taskset *tset)
+static void perf_cgroup_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
{
struct task_struct *task;
@@ -7191,8 +7188,8 @@ static void perf_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
task_function_call(task, __perf_cgroup_move, task);
}
-static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup *old_cgrp, struct task_struct *task)
+static void perf_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
+ struct task_struct *task)
{
/*
* cgroup_exit() is called in the copy_process() failure path.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d2bd464..a35cb8db 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7571,8 +7571,7 @@ static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
struct task_group, css);
}
-static struct cgroup_subsys_state *
-cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp)
{
struct task_group *tg, *parent;
@@ -7589,15 +7588,14 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
return &tg->css;
}
-static void
-cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+static void cpu_cgroup_destroy(struct cgroup *cgrp)
{
struct task_group *tg = cgroup_tg(cgrp);
sched_destroy_group(tg);
}
-static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+static int cpu_cgroup_can_attach(struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct task_struct *task;
@@ -7615,7 +7613,7 @@ static int cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
return 0;
}
-static void cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+static void cpu_cgroup_attach(struct cgroup *cgrp,
struct cgroup_taskset *tset)
{
struct task_struct *task;
@@ -7625,8 +7623,8 @@ static void cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
}
static void
-cpu_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup *old_cgrp, struct task_struct *task)
+cpu_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
+ struct task_struct *task)
{
/*
* cgroup_exit() is called in the copy_process() failure path.
@@ -7976,8 +7974,7 @@ struct cgroup_subsys cpu_cgroup_subsys = {
*/
/* create a new cpu accounting group */
-static struct cgroup_subsys_state *cpuacct_create(
- struct cgroup_subsys *ss, struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp)
{
struct cpuacct *ca;
@@ -8007,8 +8004,7 @@ out:
}
/* destroy an existing cpu accounting group */
-static void
-cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+static void cpuacct_destroy(struct cgroup *cgrp)
{
struct cpuacct *ca = cgroup_ca(cgrp);
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