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-rw-r--r--drivers/char/random.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 159d0700f7d8..a1576ed1d88e 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -409,6 +409,9 @@ static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait);
static struct fasync_struct *fasync;
+static DEFINE_SPINLOCK(random_ready_list_lock);
+static LIST_HEAD(random_ready_list);
+
/**********************************************************************
*
* OS independent entropy store. Here are the functions which handle
@@ -589,6 +592,22 @@ static void fast_mix(struct fast_pool *f)
f->count++;
}
+static void process_random_ready_list(void)
+{
+ unsigned long flags;
+ struct random_ready_callback *rdy, *tmp;
+
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
+ struct module *owner = rdy->owner;
+
+ list_del_init(&rdy->list);
+ rdy->func(rdy);
+ module_put(owner);
+ }
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
+}
+
/*
* Credit (or debit) the entropy store with n bits of entropy.
* Use credit_entropy_bits_safe() if the value comes from userspace
@@ -660,6 +679,7 @@ retry:
r->entropy_total = 0;
if (r == &nonblocking_pool) {
prandom_reseed_late();
+ process_random_ready_list();
wake_up_all(&urandom_init_wait);
pr_notice("random: %s pool is initialized\n", r->name);
}
@@ -1257,6 +1277,64 @@ void get_blocking_random_bytes(void *buf, int nbytes)
EXPORT_SYMBOL(get_blocking_random_bytes);
/*
+ * Add a callback function that will be invoked when the nonblocking
+ * pool is initialised.
+ *
+ * returns: 0 if callback is successfully added
+ * -EALREADY if pool is already initialised (callback not called)
+ * -ENOENT if module for callback is not alive
+ */
+int add_random_ready_callback(struct random_ready_callback *rdy)
+{
+ struct module *owner;
+ unsigned long flags;
+ int err = -EALREADY;
+
+ if (likely(nonblocking_pool.initialized))
+ return err;
+
+ owner = rdy->owner;
+ if (!try_module_get(owner))
+ return -ENOENT;
+
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ if (nonblocking_pool.initialized)
+ goto out;
+
+ owner = NULL;
+
+ list_add(&rdy->list, &random_ready_list);
+ err = 0;
+
+out:
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
+
+ module_put(owner);
+
+ return err;
+}
+EXPORT_SYMBOL(add_random_ready_callback);
+
+/*
+ * Delete a previously registered readiness callback function.
+ */
+void del_random_ready_callback(struct random_ready_callback *rdy)
+{
+ unsigned long flags;
+ struct module *owner = NULL;
+
+ spin_lock_irqsave(&random_ready_list_lock, flags);
+ if (!list_empty(&rdy->list)) {
+ list_del_init(&rdy->list);
+ owner = rdy->owner;
+ }
+ spin_unlock_irqrestore(&random_ready_list_lock, flags);
+
+ module_put(owner);
+}
+EXPORT_SYMBOL(del_random_ready_callback);
+
+/*
* This function will use the architecture-specific hardware random
* number generator if it is available. The arch-specific hw RNG will
* almost certainly be faster than what we can do in software, but it