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#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/once.h>
#include <linux/random.h>
struct __random_once_work {
struct work_struct work;
struct static_key *key;
};
static void __random_once_deferred(struct work_struct *w)
{
struct __random_once_work *work;
work = container_of(w, struct __random_once_work, work);
BUG_ON(!static_key_enabled(work->key));
static_key_slow_dec(work->key);
kfree(work);
}
static void __random_once_disable_jump(struct static_key *key)
{
struct __random_once_work *w;
w = kmalloc(sizeof(*w), GFP_ATOMIC);
if (!w)
return;
INIT_WORK(&w->work, __random_once_deferred);
w->key = key;
schedule_work(&w->work);
}
bool __get_random_once(void *buf, int nbytes, bool *done,
struct static_key *once_key)
{
static DEFINE_SPINLOCK(lock);
unsigned long flags;
spin_lock_irqsave(&lock, flags);
if (*done) {
spin_unlock_irqrestore(&lock, flags);
return false;
}
get_random_bytes(buf, nbytes);
*done = true;
spin_unlock_irqrestore(&lock, flags);
__random_once_disable_jump(once_key);
return true;
}
EXPORT_SYMBOL(__get_random_once);
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