mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![Tejun Heo](/assets/img/avatar_default.png)
percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
393 lines
9.2 KiB
C
393 lines
9.2 KiB
C
/*
|
|
* cgroup_freezer.c - control group freezer subsystem
|
|
*
|
|
* Copyright IBM Corporation, 2007
|
|
*
|
|
* Author : Cedric Le Goater <clg@fr.ibm.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of version 2.1 of the GNU Lesser General Public License
|
|
* as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it would be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/cgroup.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/freezer.h>
|
|
#include <linux/seq_file.h>
|
|
|
|
enum freezer_state {
|
|
CGROUP_THAWED = 0,
|
|
CGROUP_FREEZING,
|
|
CGROUP_FROZEN,
|
|
};
|
|
|
|
struct freezer {
|
|
struct cgroup_subsys_state css;
|
|
enum freezer_state state;
|
|
spinlock_t lock; /* protects _writes_ to state */
|
|
};
|
|
|
|
static inline struct freezer *cgroup_freezer(
|
|
struct cgroup *cgroup)
|
|
{
|
|
return container_of(
|
|
cgroup_subsys_state(cgroup, freezer_subsys_id),
|
|
struct freezer, css);
|
|
}
|
|
|
|
static inline struct freezer *task_freezer(struct task_struct *task)
|
|
{
|
|
return container_of(task_subsys_state(task, freezer_subsys_id),
|
|
struct freezer, css);
|
|
}
|
|
|
|
int cgroup_frozen(struct task_struct *task)
|
|
{
|
|
struct freezer *freezer;
|
|
enum freezer_state state;
|
|
|
|
task_lock(task);
|
|
freezer = task_freezer(task);
|
|
state = freezer->state;
|
|
task_unlock(task);
|
|
|
|
return state == CGROUP_FROZEN;
|
|
}
|
|
|
|
/*
|
|
* cgroups_write_string() limits the size of freezer state strings to
|
|
* CGROUP_LOCAL_BUFFER_SIZE
|
|
*/
|
|
static const char *freezer_state_strs[] = {
|
|
"THAWED",
|
|
"FREEZING",
|
|
"FROZEN",
|
|
};
|
|
|
|
/*
|
|
* State diagram
|
|
* Transitions are caused by userspace writes to the freezer.state file.
|
|
* The values in parenthesis are state labels. The rest are edge labels.
|
|
*
|
|
* (THAWED) --FROZEN--> (FREEZING) --FROZEN--> (FROZEN)
|
|
* ^ ^ | |
|
|
* | \_______THAWED_______/ |
|
|
* \__________________________THAWED____________/
|
|
*/
|
|
|
|
struct cgroup_subsys freezer_subsys;
|
|
|
|
/* Locks taken and their ordering
|
|
* ------------------------------
|
|
* css_set_lock
|
|
* cgroup_mutex (AKA cgroup_lock)
|
|
* task->alloc_lock (AKA task_lock)
|
|
* freezer->lock
|
|
* task->sighand->siglock
|
|
*
|
|
* cgroup code forces css_set_lock to be taken before task->alloc_lock
|
|
*
|
|
* freezer_create(), freezer_destroy():
|
|
* cgroup_mutex [ by cgroup core ]
|
|
*
|
|
* can_attach():
|
|
* cgroup_mutex
|
|
*
|
|
* cgroup_frozen():
|
|
* task->alloc_lock (to get task's cgroup)
|
|
*
|
|
* freezer_fork() (preserving fork() performance means can't take cgroup_mutex):
|
|
* task->alloc_lock (to get task's cgroup)
|
|
* freezer->lock
|
|
* sighand->siglock (if the cgroup is freezing)
|
|
*
|
|
* freezer_read():
|
|
* cgroup_mutex
|
|
* freezer->lock
|
|
* read_lock css_set_lock (cgroup iterator start)
|
|
*
|
|
* freezer_write() (freeze):
|
|
* cgroup_mutex
|
|
* freezer->lock
|
|
* read_lock css_set_lock (cgroup iterator start)
|
|
* sighand->siglock
|
|
*
|
|
* freezer_write() (unfreeze):
|
|
* cgroup_mutex
|
|
* freezer->lock
|
|
* read_lock css_set_lock (cgroup iterator start)
|
|
* task->alloc_lock (to prevent races with freeze_task())
|
|
* sighand->siglock
|
|
*/
|
|
static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
|
|
struct cgroup *cgroup)
|
|
{
|
|
struct freezer *freezer;
|
|
|
|
freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
|
|
if (!freezer)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
spin_lock_init(&freezer->lock);
|
|
freezer->state = CGROUP_THAWED;
|
|
return &freezer->css;
|
|
}
|
|
|
|
static void freezer_destroy(struct cgroup_subsys *ss,
|
|
struct cgroup *cgroup)
|
|
{
|
|
kfree(cgroup_freezer(cgroup));
|
|
}
|
|
|
|
/* Task is frozen or will freeze immediately when next it gets woken */
|
|
static bool is_task_frozen_enough(struct task_struct *task)
|
|
{
|
|
return frozen(task) ||
|
|
(task_is_stopped_or_traced(task) && freezing(task));
|
|
}
|
|
|
|
/*
|
|
* The call to cgroup_lock() in the freezer.state write method prevents
|
|
* 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,
|
|
struct task_struct *task, bool threadgroup)
|
|
{
|
|
struct freezer *freezer;
|
|
|
|
/*
|
|
* Anything frozen can't move or be moved to/from.
|
|
*
|
|
* Since orig_freezer->state == FROZEN means that @task has been
|
|
* frozen, so it's sufficient to check the latter condition.
|
|
*/
|
|
|
|
if (is_task_frozen_enough(task))
|
|
return -EBUSY;
|
|
|
|
freezer = cgroup_freezer(new_cgroup);
|
|
if (freezer->state == CGROUP_FROZEN)
|
|
return -EBUSY;
|
|
|
|
if (threadgroup) {
|
|
struct task_struct *c;
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
|
|
if (is_task_frozen_enough(c)) {
|
|
rcu_read_unlock();
|
|
return -EBUSY;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
|
|
{
|
|
struct freezer *freezer;
|
|
|
|
/*
|
|
* No lock is needed, since the task isn't on tasklist yet,
|
|
* so it can't be moved to another cgroup, which means the
|
|
* freezer won't be removed and will be valid during this
|
|
* function call.
|
|
*/
|
|
freezer = task_freezer(task);
|
|
|
|
/*
|
|
* The root cgroup is non-freezable, so we can skip the
|
|
* following check.
|
|
*/
|
|
if (!freezer->css.cgroup->parent)
|
|
return;
|
|
|
|
spin_lock_irq(&freezer->lock);
|
|
BUG_ON(freezer->state == CGROUP_FROZEN);
|
|
|
|
/* Locking avoids race with FREEZING -> THAWED transitions. */
|
|
if (freezer->state == CGROUP_FREEZING)
|
|
freeze_task(task, true);
|
|
spin_unlock_irq(&freezer->lock);
|
|
}
|
|
|
|
/*
|
|
* caller must hold freezer->lock
|
|
*/
|
|
static void update_freezer_state(struct cgroup *cgroup,
|
|
struct freezer *freezer)
|
|
{
|
|
struct cgroup_iter it;
|
|
struct task_struct *task;
|
|
unsigned int nfrozen = 0, ntotal = 0;
|
|
|
|
cgroup_iter_start(cgroup, &it);
|
|
while ((task = cgroup_iter_next(cgroup, &it))) {
|
|
ntotal++;
|
|
if (is_task_frozen_enough(task))
|
|
nfrozen++;
|
|
}
|
|
|
|
/*
|
|
* Transition to FROZEN when no new tasks can be added ensures
|
|
* that we never exist in the FROZEN state while there are unfrozen
|
|
* tasks.
|
|
*/
|
|
if (nfrozen == ntotal)
|
|
freezer->state = CGROUP_FROZEN;
|
|
else if (nfrozen > 0)
|
|
freezer->state = CGROUP_FREEZING;
|
|
else
|
|
freezer->state = CGROUP_THAWED;
|
|
cgroup_iter_end(cgroup, &it);
|
|
}
|
|
|
|
static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
|
|
struct seq_file *m)
|
|
{
|
|
struct freezer *freezer;
|
|
enum freezer_state state;
|
|
|
|
if (!cgroup_lock_live_group(cgroup))
|
|
return -ENODEV;
|
|
|
|
freezer = cgroup_freezer(cgroup);
|
|
spin_lock_irq(&freezer->lock);
|
|
state = freezer->state;
|
|
if (state == CGROUP_FREEZING) {
|
|
/* We change from FREEZING to FROZEN lazily if the cgroup was
|
|
* only partially frozen when we exitted write. */
|
|
update_freezer_state(cgroup, freezer);
|
|
state = freezer->state;
|
|
}
|
|
spin_unlock_irq(&freezer->lock);
|
|
cgroup_unlock();
|
|
|
|
seq_puts(m, freezer_state_strs[state]);
|
|
seq_putc(m, '\n');
|
|
return 0;
|
|
}
|
|
|
|
static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
|
|
{
|
|
struct cgroup_iter it;
|
|
struct task_struct *task;
|
|
unsigned int num_cant_freeze_now = 0;
|
|
|
|
freezer->state = CGROUP_FREEZING;
|
|
cgroup_iter_start(cgroup, &it);
|
|
while ((task = cgroup_iter_next(cgroup, &it))) {
|
|
if (!freeze_task(task, true))
|
|
continue;
|
|
if (is_task_frozen_enough(task))
|
|
continue;
|
|
if (!freezing(task) && !freezer_should_skip(task))
|
|
num_cant_freeze_now++;
|
|
}
|
|
cgroup_iter_end(cgroup, &it);
|
|
|
|
return num_cant_freeze_now ? -EBUSY : 0;
|
|
}
|
|
|
|
static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
|
|
{
|
|
struct cgroup_iter it;
|
|
struct task_struct *task;
|
|
|
|
cgroup_iter_start(cgroup, &it);
|
|
while ((task = cgroup_iter_next(cgroup, &it))) {
|
|
thaw_process(task);
|
|
}
|
|
cgroup_iter_end(cgroup, &it);
|
|
|
|
freezer->state = CGROUP_THAWED;
|
|
}
|
|
|
|
static int freezer_change_state(struct cgroup *cgroup,
|
|
enum freezer_state goal_state)
|
|
{
|
|
struct freezer *freezer;
|
|
int retval = 0;
|
|
|
|
freezer = cgroup_freezer(cgroup);
|
|
|
|
spin_lock_irq(&freezer->lock);
|
|
|
|
update_freezer_state(cgroup, freezer);
|
|
if (goal_state == freezer->state)
|
|
goto out;
|
|
|
|
switch (goal_state) {
|
|
case CGROUP_THAWED:
|
|
unfreeze_cgroup(cgroup, freezer);
|
|
break;
|
|
case CGROUP_FROZEN:
|
|
retval = try_to_freeze_cgroup(cgroup, freezer);
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
out:
|
|
spin_unlock_irq(&freezer->lock);
|
|
|
|
return retval;
|
|
}
|
|
|
|
static int freezer_write(struct cgroup *cgroup,
|
|
struct cftype *cft,
|
|
const char *buffer)
|
|
{
|
|
int retval;
|
|
enum freezer_state goal_state;
|
|
|
|
if (strcmp(buffer, freezer_state_strs[CGROUP_THAWED]) == 0)
|
|
goal_state = CGROUP_THAWED;
|
|
else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
|
|
goal_state = CGROUP_FROZEN;
|
|
else
|
|
return -EINVAL;
|
|
|
|
if (!cgroup_lock_live_group(cgroup))
|
|
return -ENODEV;
|
|
retval = freezer_change_state(cgroup, goal_state);
|
|
cgroup_unlock();
|
|
return retval;
|
|
}
|
|
|
|
static struct cftype files[] = {
|
|
{
|
|
.name = "state",
|
|
.read_seq_string = freezer_read,
|
|
.write_string = freezer_write,
|
|
},
|
|
};
|
|
|
|
static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
|
|
{
|
|
if (!cgroup->parent)
|
|
return 0;
|
|
return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
|
|
}
|
|
|
|
struct cgroup_subsys freezer_subsys = {
|
|
.name = "freezer",
|
|
.create = freezer_create,
|
|
.destroy = freezer_destroy,
|
|
.populate = freezer_populate,
|
|
.subsys_id = freezer_subsys_id,
|
|
.can_attach = freezer_can_attach,
|
|
.attach = NULL,
|
|
.fork = freezer_fork,
|
|
.exit = NULL,
|
|
};
|