* [PATCH 1/2] cgroup: make serial_nr_cursor available throughout cgroup.c
@ 2013-06-18 10:48 Li Zefan
2013-06-18 10:48 ` [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre() Li Zefan
2013-06-18 10:53 ` [PATCH 1/2][UPDATED] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
0 siblings, 2 replies; 6+ messages in thread
From: Li Zefan @ 2013-06-18 10:48 UTC (permalink / raw)
To: Tejun Heo, LKML, cgroups
The next patch will use it to determine if a cgroup is newly created
while we're iterating the cgroup hierarchy.
Signed-off-by: Li Zefan <lizefan@huawei.com>
---
These two patches are based on the fixes I just sent.
---
kernel/cgroup.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e8a40e3..b1d98f2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -198,6 +198,15 @@ static DEFINE_IDR(cgroup_hierarchy_idr);
static struct cgroup_name root_cgroup_name = { .name = "/" };
+/*
+ * Assign a monotonically increasing serial number. It guarantees
+ * cgroups with bigger numbers are newer than those with smaller
+ * numbers. Also with the list appending, it guarantees that sibling
+ * cgroups are always sorted in the ascending serial number order on
+ * the parent's ->children.
+ */
+static atomic64_t cgroup_serial_nr_cursor = ATOMIC64_INIT(0);
+
/* This flag indicates whether tasks in the fork and exit paths should
* check for fork/exit handlers to call. This avoids us having to do
* extra work in the fork/exit path if none of the subsystems need to
@@ -4212,7 +4221,6 @@ static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
umode_t mode)
{
- static atomic64_t serial_nr_cursor = ATOMIC64_INIT(0);
struct cgroup *cgrp;
struct cgroup_name *name;
struct cgroupfs_root *root = parent->root;
@@ -4305,7 +4313,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
* sorted in the ascending serial number order on the parent's
* ->children.
*/
- cgrp->serial_nr = atomic64_inc_return(&serial_nr_cursor);
+ cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor);
/* allocation complete, commit to creation */
list_add_tail(&cgrp->allcg_node, &root->allcg_list);
--
1.8.0.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre()
2013-06-18 10:48 [PATCH 1/2] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
@ 2013-06-18 10:48 ` Li Zefan
2013-06-18 18:16 ` Tejun Heo
2013-06-18 18:18 ` [PATCH 3/3] cgroup: clean up cgroup_serial_nr_cursor Tejun Heo
2013-06-18 10:53 ` [PATCH 1/2][UPDATED] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
1 sibling, 2 replies; 6+ messages in thread
From: Li Zefan @ 2013-06-18 10:48 UTC (permalink / raw)
To: Tejun Heo; +Cc: LKML, cgroups
We used root->allcg_list to iterate cgroup hierarchy because at that time
cgroup_for_each_descendant_pre() hasn't been invented.
Signed-off-by: Li Zefan <lizefan@huawei.com>
---
include/linux/cgroup.h | 6 -----
kernel/cgroup.c | 62 +++++++++++++++++++++++++++-----------------------
2 files changed, 33 insertions(+), 35 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 835918c..f70b116 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -206,9 +206,6 @@ struct cgroup {
*/
struct list_head cset_links;
- struct list_head allcg_node; /* cgroupfs_root->allcg_list */
- struct list_head cft_q_node; /* used during cftype add/rm */
-
/*
* Linked list running through all cgroups that can
* potentially be reaped by the release agent. Protected by
@@ -317,9 +314,6 @@ struct cgroupfs_root {
/* A list running through the active hierarchies */
struct list_head root_list;
- /* All cgroups on this root, cgroup_mutex protected */
- struct list_head allcg_list;
-
/* Hierarchy-specific flags */
unsigned long flags;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b1d98f2..bc46c28 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1399,7 +1399,6 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->children);
INIT_LIST_HEAD(&cgrp->files);
INIT_LIST_HEAD(&cgrp->cset_links);
- INIT_LIST_HEAD(&cgrp->allcg_node);
INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
@@ -1414,12 +1413,10 @@ static void init_cgroup_root(struct cgroupfs_root *root)
INIT_LIST_HEAD(&root->subsys_list);
INIT_LIST_HEAD(&root->root_list);
- INIT_LIST_HEAD(&root->allcg_list);
root->number_of_cgroups = 1;
cgrp->root = root;
cgrp->name = &root_cgroup_name;
init_cgroup_housekeeping(cgrp);
- list_add_tail(&cgrp->allcg_node, &root->allcg_list);
}
static int cgroup_init_root_id(struct cgroupfs_root *root)
@@ -2775,65 +2772,74 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
return ret;
}
-static DEFINE_MUTEX(cgroup_cft_mutex);
-
static void cgroup_cfts_prepare(void)
- __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex)
+ __acquires(&cgroup_mutex)
{
/*
* Thanks to the entanglement with vfs inode locking, we can't walk
* the existing cgroups under cgroup_mutex and create files.
- * Instead, we increment reference on all cgroups and build list of
- * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
- * exclusive access to the field.
+ * Instead, we use cgroup_for_each_descendant_pre() and drop RCU
+ * read lock before calling cgroup_addrm_files().
*/
- mutex_lock(&cgroup_cft_mutex);
mutex_lock(&cgroup_mutex);
}
static void cgroup_cfts_commit(struct cgroup_subsys *ss,
struct cftype *cfts, bool is_add)
- __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
+ __releases(&cgroup_mutex)
{
LIST_HEAD(pending);
- struct cgroup *cgrp, *n;
+ struct cgroup *cgrp, *root = &ss->root->top_cgroup;
struct super_block *sb = ss->root->sb;
+ struct inode *inode;
+ struct dentry *prev = NULL;
+ u64 serial_nr = atomic64_read(&cgroup_serial_nr_cursor);
/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
- if (cfts && ss->root != &rootnode &&
- atomic_inc_not_zero(&sb->s_active)) {
- list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) {
- dget(cgrp->dentry);
- list_add_tail(&cgrp->cft_q_node, &pending);
- }
- } else {
- sb = NULL;
+ if (!cfts || ss->root == &rootnode ||
+ !atomic_inc_not_zero(&sb->s_active)) {
+ mutex_unlock(&cgroup_mutex);
+ return;
}
+ mutex_unlock(&cgroup_mutex);
+ inode = root->dentry->d_inode;
+ mutex_lock(&inode->i_mutex);
+ mutex_lock(&cgroup_mutex);
+ cgroup_addrm_files(root, ss, cfts, is_add);
mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
/*
* All new cgroups will see @cfts update on @ss->cftsets. Add/rm
* files for all cgroups which were created before.
*/
- list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) {
- struct inode *inode = cgrp->dentry->d_inode;
+ rcu_read_lock();
+ cgroup_for_each_descendant_pre(cgrp, root) {
+ if (cgroup_is_dead(cgrp))
+ continue;
+
+ inode = cgrp->dentry->d_inode;
+ dget(cgrp->dentry);
+ rcu_read_unlock();
+
+ dput(prev);
+ prev = cgrp->dentry;
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
- if (!cgroup_is_dead(cgrp))
+ if (cgrp->serial_nr <= serial_nr && !cgroup_is_dead(cgrp))
cgroup_addrm_files(cgrp, ss, cfts, is_add);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
- list_del_init(&cgrp->cft_q_node);
- dput(cgrp->dentry);
+ rcu_read_lock();
}
+ rcu_read_unlock();
+ dput(prev);
if (sb)
deactivate_super(sb);
-
- mutex_unlock(&cgroup_cft_mutex);
}
/**
@@ -4316,7 +4322,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor);
/* allocation complete, commit to creation */
- list_add_tail(&cgrp->allcg_node, &root->allcg_list);
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
@@ -4555,7 +4560,6 @@ static void cgroup_offline_fn(struct work_struct *work)
/* delete this cgroup from parent->children */
list_del_rcu(&cgrp->sibling);
- list_del_init(&cgrp->allcg_node);
dput(d);
--
1.8.0.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 1/2][UPDATED] cgroup: make serial_nr_cursor available throughout cgroup.c
2013-06-18 10:48 [PATCH 1/2] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
2013-06-18 10:48 ` [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre() Li Zefan
@ 2013-06-18 10:53 ` Li Zefan
2013-06-18 18:16 ` Tejun Heo
1 sibling, 1 reply; 6+ messages in thread
From: Li Zefan @ 2013-06-18 10:53 UTC (permalink / raw)
To: Tejun Heo; +Cc: LKML, cgroups
The next patch will use it to determine if a cgroup is newly created
while we're iterating the cgroup hierarchy.
Signed-off-by: Li Zefan <lizefan@huawei.com>
---
forgot to remove the old comment in cgroup_create().
---
kernel/cgroup.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e8a40e3..60383e8 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -198,6 +198,15 @@ static DEFINE_IDR(cgroup_hierarchy_idr);
static struct cgroup_name root_cgroup_name = { .name = "/" };
+/*
+ * Assign a monotonically increasing serial number. It guarantees
+ * cgroups with bigger numbers are newer than those with smaller
+ * numbers. Also with the list appending, it guarantees that sibling
+ * cgroups are always sorted in the ascending serial number order on
+ * the parent's ->children.
+ */
+static atomic64_t cgroup_serial_nr_cursor = ATOMIC64_INIT(0);
+
/* This flag indicates whether tasks in the fork and exit paths should
* check for fork/exit handlers to call. This avoids us having to do
* extra work in the fork/exit path if none of the subsystems need to
@@ -4212,7 +4221,6 @@ static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
umode_t mode)
{
- static atomic64_t serial_nr_cursor = ATOMIC64_INIT(0);
struct cgroup *cgrp;
struct cgroup_name *name;
struct cgroupfs_root *root = parent->root;
@@ -4299,13 +4307,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
goto err_free_all;
lockdep_assert_held(&dentry->d_inode->i_mutex);
- /*
- * Assign a monotonically increasing serial number. With the list
- * appending below, it guarantees that sibling cgroups are always
- * sorted in the ascending serial number order on the parent's
- * ->children.
- */
- cgrp->serial_nr = atomic64_inc_return(&serial_nr_cursor);
+ cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor);
/* allocation complete, commit to creation */
list_add_tail(&cgrp->allcg_node, &root->allcg_list);
--
1.8.0.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2][UPDATED] cgroup: make serial_nr_cursor available throughout cgroup.c
2013-06-18 10:53 ` [PATCH 1/2][UPDATED] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
@ 2013-06-18 18:16 ` Tejun Heo
0 siblings, 0 replies; 6+ messages in thread
From: Tejun Heo @ 2013-06-18 18:16 UTC (permalink / raw)
To: Li Zefan; +Cc: LKML, cgroups
>From 794611a1dfcb055d7d41ce133378dd8197d73e38 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan@huawei.com>
Date: Tue, 18 Jun 2013 18:53:53 +0800
The next patch will use it to determine if a cgroup is newly created
while we're iterating the cgroup hierarchy.
tj: Rephrased the comment on top of cgroup_serial_nr_cursor.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
Applied to cgroup/for-3.11 with minor update.
Thanks.
kernel/cgroup.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1d4f471..e6571ca 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -198,6 +198,15 @@ static DEFINE_IDR(cgroup_hierarchy_idr);
static struct cgroup_name root_cgroup_name = { .name = "/" };
+/*
+ * Assign a monotonically increasing serial number to cgroups. It
+ * guarantees cgroups with bigger numbers are newer than those with smaller
+ * numbers. Also, as cgroups are always appended to the parent's
+ * ->children list, it guarantees that sibling cgroups are always sorted in
+ * the ascending serial number order on the list.
+ */
+static atomic64_t cgroup_serial_nr_cursor = ATOMIC64_INIT(0);
+
/* This flag indicates whether tasks in the fork and exit paths should
* check for fork/exit handlers to call. This avoids us having to do
* extra work in the fork/exit path if none of the subsystems need to
@@ -4222,7 +4231,6 @@ static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
umode_t mode)
{
- static atomic64_t serial_nr_cursor = ATOMIC64_INIT(0);
struct cgroup *cgrp;
struct cgroup_name *name;
struct cgroupfs_root *root = parent->root;
@@ -4309,13 +4317,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
goto err_free_all;
lockdep_assert_held(&dentry->d_inode->i_mutex);
- /*
- * Assign a monotonically increasing serial number. With the list
- * appending below, it guarantees that sibling cgroups are always
- * sorted in the ascending serial number order on the parent's
- * ->children.
- */
- cgrp->serial_nr = atomic64_inc_return(&serial_nr_cursor);
+ cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor);
/* allocation complete, commit to creation */
list_add_tail(&cgrp->allcg_node, &root->allcg_list);
--
1.8.2.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre()
2013-06-18 10:48 ` [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre() Li Zefan
@ 2013-06-18 18:16 ` Tejun Heo
2013-06-18 18:18 ` [PATCH 3/3] cgroup: clean up cgroup_serial_nr_cursor Tejun Heo
1 sibling, 0 replies; 6+ messages in thread
From: Tejun Heo @ 2013-06-18 18:16 UTC (permalink / raw)
To: Li Zefan; +Cc: LKML, cgroups
>From e8c82d20a9f729cf4b9f73043f7fd4e0872bebfd Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan@huawei.com>
Date: Tue, 18 Jun 2013 18:48:37 +0800
We used root->allcg_list to iterate cgroup hierarchy because at that time
cgroup_for_each_descendant_pre() hasn't been invented.
tj: In cgroup_cfts_commit(), s/@serial_nr/@update_upto/, move the
assignment right above releasing cgroup_mutex and explain what's
going on there.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
Applied to cgroup/for-3.11 with some minor updates.
Thanks.
include/linux/cgroup.h | 6 ----
kernel/cgroup.c | 80 +++++++++++++++++++++++++++-----------------------
2 files changed, 44 insertions(+), 42 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f975227..b283658 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -206,9 +206,6 @@ struct cgroup {
*/
struct list_head cset_links;
- struct list_head allcg_node; /* cgroupfs_root->allcg_list */
- struct list_head cft_q_node; /* used during cftype add/rm */
-
/*
* Linked list running through all cgroups that can
* potentially be reaped by the release agent. Protected by
@@ -313,9 +310,6 @@ struct cgroupfs_root {
/* A list running through the active hierarchies */
struct list_head root_list;
- /* All cgroups on this root, cgroup_mutex protected */
- struct list_head allcg_list;
-
/* Hierarchy-specific flags */
unsigned long flags;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e6571ca..0ed7d8d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1399,7 +1399,6 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
INIT_LIST_HEAD(&cgrp->children);
INIT_LIST_HEAD(&cgrp->files);
INIT_LIST_HEAD(&cgrp->cset_links);
- INIT_LIST_HEAD(&cgrp->allcg_node);
INIT_LIST_HEAD(&cgrp->release_list);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
@@ -1414,12 +1413,10 @@ static void init_cgroup_root(struct cgroupfs_root *root)
INIT_LIST_HEAD(&root->subsys_list);
INIT_LIST_HEAD(&root->root_list);
- INIT_LIST_HEAD(&root->allcg_list);
root->number_of_cgroups = 1;
cgrp->root = root;
cgrp->name = &root_cgroup_name;
init_cgroup_housekeeping(cgrp);
- list_add_tail(&cgrp->allcg_node, &root->allcg_list);
}
static int cgroup_init_root_id(struct cgroupfs_root *root)
@@ -2785,65 +2782,78 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
return ret;
}
-static DEFINE_MUTEX(cgroup_cft_mutex);
-
static void cgroup_cfts_prepare(void)
- __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex)
+ __acquires(&cgroup_mutex)
{
/*
* Thanks to the entanglement with vfs inode locking, we can't walk
* the existing cgroups under cgroup_mutex and create files.
- * Instead, we increment reference on all cgroups and build list of
- * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure
- * exclusive access to the field.
+ * Instead, we use cgroup_for_each_descendant_pre() and drop RCU
+ * read lock before calling cgroup_addrm_files().
*/
- mutex_lock(&cgroup_cft_mutex);
mutex_lock(&cgroup_mutex);
}
static void cgroup_cfts_commit(struct cgroup_subsys *ss,
struct cftype *cfts, bool is_add)
- __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
+ __releases(&cgroup_mutex)
{
LIST_HEAD(pending);
- struct cgroup *cgrp, *n;
+ struct cgroup *cgrp, *root = &ss->root->top_cgroup;
struct super_block *sb = ss->root->sb;
+ struct dentry *prev = NULL;
+ struct inode *inode;
+ u64 update_upto;
/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
- if (cfts && ss->root != &rootnode &&
- atomic_inc_not_zero(sb->s_active)) {
- list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) {
- dget(cgrp->dentry);
- list_add_tail(&cgrp->cft_q_node, &pending);
- }
- } else {
- sb = NULL;
+ if (!cfts || ss->root == &rootnode ||
+ !atomic_inc_not_zero(&sb->s_active)) {
+ mutex_unlock(&cgroup_mutex);
+ return;
}
- mutex_unlock(&cgroup_mutex);
-
/*
- * All new cgroups will see @cfts update on @ss->cftsets. Add/rm
- * files for all cgroups which were created before.
+ * All cgroups which are created after we drop cgroup_mutex will
+ * have the updated set of files, so we only need to update the
+ * cgroups created before the current @cgroup_serial_nr_cursor.
*/
- list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) {
- struct inode *inode = cgrp->dentry->d_inode;
+ update_upto = atomic64_read(&cgroup_serial_nr_cursor);
+
+ mutex_unlock(&cgroup_mutex);
+
+ /* @root always needs to be updated */
+ inode = root->dentry->d_inode;
+ mutex_lock(&inode->i_mutex);
+ mutex_lock(&cgroup_mutex);
+ cgroup_addrm_files(root, ss, cfts, is_add);
+ mutex_unlock(&cgroup_mutex);
+ mutex_unlock(&inode->i_mutex);
+
+ /* add/rm files for all cgroups created before */
+ rcu_read_lock();
+ cgroup_for_each_descendant_pre(cgrp, root) {
+ if (cgroup_is_dead(cgrp))
+ continue;
+
+ inode = cgrp->dentry->d_inode;
+ dget(cgrp->dentry);
+ rcu_read_unlock();
+
+ dput(prev);
+ prev = cgrp->dentry;
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
- if (!cgroup_is_dead(cgrp))
+ if (cgrp->serial_nr <= update_upto && !cgroup_is_dead(cgrp))
cgroup_addrm_files(cgrp, ss, cfts, is_add);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
- list_del_init(&cgrp->cft_q_node);
- dput(cgrp->dentry);
+ rcu_read_lock();
}
-
- if (sb)
- deactivate_super(sb);
-
- mutex_unlock(&cgroup_cft_mutex);
+ rcu_read_unlock();
+ dput(prev);
+ deactivate_super(sb);
}
/**
@@ -4320,7 +4330,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor);
/* allocation complete, commit to creation */
- list_add_tail(&cgrp->allcg_node, &root->allcg_list);
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
root->number_of_cgroups++;
@@ -4559,7 +4568,6 @@ static void cgroup_offline_fn(struct work_struct *work)
/* delete this cgroup from parent->children */
list_del_rcu(&cgrp->sibling);
- list_del_init(&cgrp->allcg_node);
dput(d);
--
1.8.2.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 3/3] cgroup: clean up cgroup_serial_nr_cursor
2013-06-18 10:48 ` [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre() Li Zefan
2013-06-18 18:16 ` Tejun Heo
@ 2013-06-18 18:18 ` Tejun Heo
1 sibling, 0 replies; 6+ messages in thread
From: Tejun Heo @ 2013-06-18 18:18 UTC (permalink / raw)
To: Li Zefan; +Cc: LKML, cgroups
>From 00356bd5f0f5e04183fb15805eb29e97c2fc20ac Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Tue, 18 Jun 2013 11:14:22 -0700
cgroup_serial_nr_cursor was created atomic64_t because I thought it
was never gonna used for anything other than assigning unique numbers
to cgroups and didn't want to worry about synchronization; however,
now we're using it as an event-stamp to distinguish cgroups created
before and after certain point which assumes that it's protected by
cgroup_mutex.
Let's make it clear by making it a u64. Also, rename it to
cgroup_serial_nr_next and make it point to the next nr to allocate so
that where it's pointing to is clear and more conventional.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
---
Applied to cgroup/for-3.11 as a follow-up.
Thanks.
kernel/cgroup.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0ed7d8d..65f333e 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -203,9 +203,10 @@ static struct cgroup_name root_cgroup_name = { .name = "/" };
* guarantees cgroups with bigger numbers are newer than those with smaller
* numbers. Also, as cgroups are always appended to the parent's
* ->children list, it guarantees that sibling cgroups are always sorted in
- * the ascending serial number order on the list.
+ * the ascending serial number order on the list. Protected by
+ * cgroup_mutex.
*/
-static atomic64_t cgroup_serial_nr_cursor = ATOMIC64_INIT(0);
+static u64 cgroup_serial_nr_next = 1;
/* This flag indicates whether tasks in the fork and exit paths should
* check for fork/exit handlers to call. This avoids us having to do
@@ -2803,7 +2804,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss,
struct super_block *sb = ss->root->sb;
struct dentry *prev = NULL;
struct inode *inode;
- u64 update_upto;
+ u64 update_before;
/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
if (!cfts || ss->root == &rootnode ||
@@ -2815,9 +2816,9 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss,
/*
* All cgroups which are created after we drop cgroup_mutex will
* have the updated set of files, so we only need to update the
- * cgroups created before the current @cgroup_serial_nr_cursor.
+ * cgroups created before the current @cgroup_serial_nr_next.
*/
- update_upto = atomic64_read(&cgroup_serial_nr_cursor);
+ update_before = cgroup_serial_nr_next;
mutex_unlock(&cgroup_mutex);
@@ -2844,7 +2845,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss,
mutex_lock(&inode->i_mutex);
mutex_lock(&cgroup_mutex);
- if (cgrp->serial_nr <= update_upto && !cgroup_is_dead(cgrp))
+ if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp))
cgroup_addrm_files(cgrp, ss, cfts, is_add);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
@@ -4327,7 +4328,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
goto err_free_all;
lockdep_assert_held(&dentry->d_inode->i_mutex);
- cgrp->serial_nr = atomic64_inc_return(&cgroup_serial_nr_cursor);
+ cgrp->serial_nr = cgroup_serial_nr_next++;
/* allocation complete, commit to creation */
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
--
1.8.2.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-06-18 18:18 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-06-18 10:48 [PATCH 1/2] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
2013-06-18 10:48 ` [PATCH 2/2] cgroup: convert cgroup_cft_commit() to use cgroup_for_each_descendant_pre() Li Zefan
2013-06-18 18:16 ` Tejun Heo
2013-06-18 18:18 ` [PATCH 3/3] cgroup: clean up cgroup_serial_nr_cursor Tejun Heo
2013-06-18 10:53 ` [PATCH 1/2][UPDATED] cgroup: make serial_nr_cursor available throughout cgroup.c Li Zefan
2013-06-18 18:16 ` Tejun Heo
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