[PATCH 1/2] res_counter: Merge res_counter_charge and res_counter_charge_nofail

Frederic Weisbecker
2012-04-24T23:11:50Z

These two functions do almost the same thing and duplicate some code.
Merge their implementation into a single common function.
res_counter_charge_locked() takes one more parameter but it doesn't seem
to be used outside res_counter.c yet anyway.

There is no (intended) change in the behaviour.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
---
Documentation/cgroups/resource_counter.txt | 4 +-
include/linux/res_counter.h | 2 +-
kernel/res_counter.c | 73 +++++++++++++---------------
3 files changed, 37 insertions(+), 42 deletions(-)

diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
index 95b24d7..f3c4ec3 100644
--- a/Documentation/cgroups/resource_counter.txt
+++ b/Documentation/cgroups/resource_counter.txt
@@ -77,11 +77,11 @@ to work with it.
where the charging failed.

d. int res_counter_charge_locked
- (struct res_counter *rc, unsigned long val)
+ (struct res_counter *rc, unsigned long val, bool force)

The same as res_counter_charge(), but it must not acquire/release the
res_counter->lock internally (it must be called with res_counter->lock
- held).
+ held). The force parameter indicates whether we can bypass the limit.

e. void res_counter_uncharge[_locked]
(struct res_counter *rc, unsigned long val)
diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index da81af0..fb20189 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -116,7 +116,7 @@ void res_counter_init(struct res_counter *counter, struct res_counter *parent);
*/

int __must_check res_counter_charge_locked(struct res_counter *counter,
- unsigned long val);
+ unsigned long val, bool force);
int __must_check res_counter_charge(struct res_counter *counter,
unsigned long val, struct res_counter **limit_fail_at);
int __must_check res_counter_charge_nofail(struct res_counter *counter,
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index d508363..07a2992 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -22,75 +22,70 @@ void res_counter_init(struct res_counter *counter, struct res_counter *parent)
counter->parent = parent;
}

-int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
+int res_counter_charge_locked(struct res_counter *counter, unsigned long val,
+ bool force)
{
+ int ret = 0;
+
if (counter->usage + val > counter->limit) {
counter->failcnt++;
- return -ENOMEM;
+ ret = -ENOMEM;
+ if (!force)
+ return ret;
}

counter->usage += val;
- if (counter->usage > counter->max_usage)
+ if (!force && counter->usage > counter->max_usage)
counter->max_usage = counter->usage;
- return 0;
+ return ret;
}

-int res_counter_charge(struct res_counter *counter, unsigned long val,
- struct res_counter **limit_fail_at)
+static int __res_counter_charge(struct res_counter *counter, unsigned long val,
+ struct res_counter **limit_fail_at, bool force)
{
- int ret;
+ int ret, r;
unsigned long flags;
struct res_counter *c, *u;

+ r = ret = 0;
*limit_fail_at = NULL;
local_irq_save(flags);
for (c = counter; c != NULL; c = c->parent) {
spin_lock(&c->lock);
- ret = res_counter_charge_locked(c, val);
+ r = res_counter_charge_locked(c, val, force);
spin_unlock(&c->lock);
- if (ret < 0) {
+ if (r < 0 && !ret) {
+ ret = r;
*limit_fail_at = c;
- goto undo;
+ if (!force)
+ break;
}
}
- ret = 0;
- goto done;
-undo:
- for (u = counter; u != c; u = u->parent) {
- spin_lock(&u->lock);
- res_counter_uncharge_locked(u, val);
- spin_unlock(&u->lock);
+
+ if (ret < 0 && !force) {
+ for (u = counter; u != c; u = u->parent) {
+ spin_lock(&u->lock);
+ res_counter_uncharge_locked(u, val);
+ spin_unlock(&u->lock);
+ }
}
-done:
local_irq_restore(flags);
+
return ret;
}

+int res_counter_charge(struct res_counter *counter, unsigned long val,
+ struct res_counter **limit_fail_at)
+{
+ return __res_counter_charge(counter, val, limit_fail_at, false);
+}
+
int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
struct res_counter **limit_fail_at)
{
- int ret, r;
- unsigned long flags;
- struct res_counter *c;
-
- r = ret = 0;
- *limit_fail_at = NULL;
- local_irq_save(flags);
- for (c = counter; c != NULL; c = c->parent) {
- spin_lock(&c->lock);
- r = res_counter_charge_locked(c, val);
- if (r)
- c->usage += val;
- spin_unlock(&c->lock);
- if (r < 0 && ret == 0) {
- *limit_fail_at = c;
- ret = r;
- }
- }
- local_irq_restore(flags);
-
- return ret;
+ return __res_counter_charge(counter, val, limit_fail_at, true);
}
+
void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
{
if (WARN_ON(counter->usage < val))
--
1.7.5.4