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Diffstat (limited to 'kernel/acct.c')
-rw-r--r--kernel/acct.c94
1 files changed, 46 insertions, 48 deletions
diff --git a/kernel/acct.c b/kernel/acct.c
index 33738ef972f3..e6c10d1a4058 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -76,10 +76,11 @@ int acct_parm[3] = {4, 2, 30};
/*
* External references and all of the globals.
*/
-static void do_acct_process(struct bsd_acct_struct *acct);
struct bsd_acct_struct {
struct fs_pin pin;
+ atomic_long_t count;
+ struct rcu_head rcu;
struct mutex lock;
int active;
unsigned long needcheck;
@@ -89,6 +90,8 @@ struct bsd_acct_struct {
struct completion done;
};
+static void do_acct_process(struct bsd_acct_struct *acct);
+
/*
* Check the amount of free space and suspend/resume accordingly.
*/
@@ -124,32 +127,56 @@ out:
return acct->active;
}
+static void acct_put(struct bsd_acct_struct *p)
+{
+ if (atomic_long_dec_and_test(&p->count))
+ kfree_rcu(p, rcu);
+}
+
+static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)
+{
+ return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;
+}
+
static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)
{
struct bsd_acct_struct *res;
again:
smp_rmb();
rcu_read_lock();
- res = ACCESS_ONCE(ns->bacct);
+ res = to_acct(ACCESS_ONCE(ns->bacct));
if (!res) {
rcu_read_unlock();
return NULL;
}
- if (!atomic_long_inc_not_zero(&res->pin.count)) {
+ if (!atomic_long_inc_not_zero(&res->count)) {
rcu_read_unlock();
cpu_relax();
goto again;
}
rcu_read_unlock();
mutex_lock(&res->lock);
- if (!res->ns) {
+ if (res != to_acct(ACCESS_ONCE(ns->bacct))) {
mutex_unlock(&res->lock);
- pin_put(&res->pin);
+ acct_put(res);
goto again;
}
return res;
}
+static void acct_pin_kill(struct fs_pin *pin)
+{
+ struct bsd_acct_struct *acct = to_acct(pin);
+ mutex_lock(&acct->lock);
+ do_acct_process(acct);
+ schedule_work(&acct->work);
+ wait_for_completion(&acct->done);
+ cmpxchg(&acct->ns->bacct, pin, NULL);
+ mutex_unlock(&acct->lock);
+ pin_remove(pin);
+ acct_put(acct);
+}
+
static void close_work(struct work_struct *work)
{
struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);
@@ -160,44 +187,13 @@ static void close_work(struct work_struct *work)
complete(&acct->done);
}
-static void acct_kill(struct bsd_acct_struct *acct,
- struct bsd_acct_struct *new)
-{
- if (acct) {
- struct pid_namespace *ns = acct->ns;
- do_acct_process(acct);
- INIT_WORK(&acct->work, close_work);
- init_completion(&acct->done);
- schedule_work(&acct->work);
- wait_for_completion(&acct->done);
- pin_remove(&acct->pin);
- ns->bacct = new;
- acct->ns = NULL;
- atomic_long_dec(&acct->pin.count);
- mutex_unlock(&acct->lock);
- pin_put(&acct->pin);
- }
-}
-
-static void acct_pin_kill(struct fs_pin *pin)
-{
- struct bsd_acct_struct *acct;
- acct = container_of(pin, struct bsd_acct_struct, pin);
- mutex_lock(&acct->lock);
- if (!acct->ns) {
- mutex_unlock(&acct->lock);
- pin_put(pin);
- acct = NULL;
- }
- acct_kill(acct, NULL);
-}
-
static int acct_on(struct filename *pathname)
{
struct file *file;
struct vfsmount *mnt, *internal;
struct pid_namespace *ns = task_active_pid_ns(current);
- struct bsd_acct_struct *acct, *old;
+ struct bsd_acct_struct *acct;
+ struct fs_pin *old;
int err;
acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
@@ -238,21 +234,21 @@ static int acct_on(struct filename *pathname)
mnt = file->f_path.mnt;
file->f_path.mnt = internal;
- atomic_long_set(&acct->pin.count, 1);
- acct->pin.kill = acct_pin_kill;
+ atomic_long_set(&acct->count, 1);
+ init_fs_pin(&acct->pin, acct_pin_kill);
acct->file = file;
acct->needcheck = jiffies;
acct->ns = ns;
mutex_init(&acct->lock);
+ INIT_WORK(&acct->work, close_work);
+ init_completion(&acct->done);
mutex_lock_nested(&acct->lock, 1); /* nobody has seen it yet */
pin_insert(&acct->pin, mnt);
- old = acct_get(ns);
- if (old)
- acct_kill(old, acct);
- else
- ns->bacct = acct;
+ rcu_read_lock();
+ old = xchg(&ns->bacct, &acct->pin);
mutex_unlock(&acct->lock);
+ pin_kill(old);
mnt_drop_write(mnt);
mntput(mnt);
return 0;
@@ -288,7 +284,8 @@ SYSCALL_DEFINE1(acct, const char __user *, name)
mutex_unlock(&acct_on_mutex);
putname(tmp);
} else {
- acct_kill(acct_get(task_active_pid_ns(current)), NULL);
+ rcu_read_lock();
+ pin_kill(task_active_pid_ns(current)->bacct);
}
return error;
@@ -296,7 +293,8 @@ SYSCALL_DEFINE1(acct, const char __user *, name)
void acct_exit_ns(struct pid_namespace *ns)
{
- acct_kill(acct_get(ns), NULL);
+ rcu_read_lock();
+ pin_kill(ns->bacct);
}
/*
@@ -576,7 +574,7 @@ static void slow_acct_process(struct pid_namespace *ns)
if (acct) {
do_acct_process(acct);
mutex_unlock(&acct->lock);
- pin_put(&acct->pin);
+ acct_put(acct);
}
}
}