1 files changed, 25 insertions, 30 deletions

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 16f227b995e8..cc002b0c2f0c 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -52,7 +52,7 @@ MODULE_PARM_DESC(default_quality,
 
 static void drop_current_rng(void);
 static int hwrng_init(struct hwrng *rng);
-static void hwrng_manage_rngd(struct hwrng *rng);
+static int hwrng_fillfn(void *unused);
 
 static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
 			       int wait);
@@ -96,6 +96,15 @@ static int set_current_rng(struct hwrng *rng)
 	drop_current_rng();
 	current_rng = rng;
 
+	/* if necessary, start hwrng thread */
+	if (!hwrng_fill) {
+		hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng");
+		if (IS_ERR(hwrng_fill)) {
+			pr_err("hwrng_fill thread creation failed\n");
+			hwrng_fill = NULL;
+		}
+	}
+
 	return 0;
 }
 
@@ -167,8 +176,6 @@ skip_init:
 		rng->quality = 1024;
 	current_quality = rng->quality; /* obsolete */
 
-	hwrng_manage_rngd(rng);
-
 	return 0;
 }
 
@@ -454,10 +461,6 @@ static ssize_t rng_quality_store(struct device *dev,
 	/* the best available RNG may have changed */
 	ret = enable_best_rng();
 
-	/* start/stop rngd if necessary */
-	if (current_rng)
-		hwrng_manage_rngd(current_rng);
-
 out:
 	mutex_unlock(&rng_mutex);
 	return ret ? ret : len;
@@ -507,16 +510,14 @@ static int hwrng_fillfn(void *unused)
 			rng->quality = current_quality; /* obsolete */
 		quality = rng->quality;
 		mutex_unlock(&reading_mutex);
-		put_rng(rng);
 
-		if (!quality)
-			break;
+		if (rc <= 0)
+			hwrng_msleep(rng, 10000);
 
-		if (rc <= 0) {
-			pr_warn("hwrng: no data available\n");
-			msleep_interruptible(10000);
+		put_rng(rng);
+
+		if (rc <= 0)
 			continue;
-		}
 
 		/* If we cannot credit at least one bit of entropy,
 		 * keep track of the remainder for the next iteration
@@ -533,22 +534,6 @@ static int hwrng_fillfn(void *unused)
 	return 0;
 }
 
-static void hwrng_manage_rngd(struct hwrng *rng)
-{
-	if (WARN_ON(!mutex_is_locked(&rng_mutex)))
-		return;
-
-	if (rng->quality == 0 && hwrng_fill)
-		kthread_stop(hwrng_fill);
-	if (rng->quality > 0 && !hwrng_fill) {
-		hwrng_fill = kthread_run(hwrng_fillfn, NULL, "hwrng");
-		if (IS_ERR(hwrng_fill)) {
-			pr_err("hwrng_fill thread creation failed\n");
-			hwrng_fill = NULL;
-		}
-	}
-}
-
 int hwrng_register(struct hwrng *rng)
 {
 	int err = -EINVAL;
@@ -570,6 +555,7 @@ int hwrng_register(struct hwrng *rng)
 
 	init_completion(&rng->cleanup_done);
 	complete(&rng->cleanup_done);
+	init_completion(&rng->dying);
 
 	if (!current_rng ||
 	    (!cur_rng_set_by_user && rng->quality > current_rng->quality)) {
@@ -617,6 +603,7 @@ void hwrng_unregister(struct hwrng *rng)
 
 	old_rng = current_rng;
 	list_del(&rng->list);
+	complete_all(&rng->dying);
 	if (current_rng == rng) {
 		err = enable_best_rng();
 		if (err) {
@@ -685,6 +672,14 @@ void devm_hwrng_unregister(struct device *dev, struct hwrng *rng)
 }
 EXPORT_SYMBOL_GPL(devm_hwrng_unregister);
 
+long hwrng_msleep(struct hwrng *rng, unsigned int msecs)
+{
+	unsigned long timeout = msecs_to_jiffies(msecs) + 1;
+
+	return wait_for_completion_interruptible_timeout(&rng->dying, timeout);
+}
+EXPORT_SYMBOL_GPL(hwrng_msleep);
+
 static int __init hwrng_modinit(void)
 {
 	int ret;