Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull /dev/random updates from Ted Ts'o:
 "A few random (cough, cough) cleanups for the /dev/random driver"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  drivers/char/random.c: remove unused dont_count_entropy
  random: optimize add_interrupt_randomness
  random: always fill buffer in get_random_bytes_wait
  random: use a tighter cap in credit_entropy_bits_safe()

drivers/char/random.c

@@ -709,7 +709,8 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 		}
 
 		/* should we wake readers? */
-		if (entropy_bits >= random_read_wakeup_bits) {
+		if (entropy_bits >= random_read_wakeup_bits &&
+		    wq_has_sleeper(&random_read_wait)) {
 			wake_up_interruptible(&random_read_wait);
 			kill_fasync(&fasync, SIGIO, POLL_IN);
 		}
@@ -732,7 +733,7 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 
 static int credit_entropy_bits_safe(struct entropy_store *r, int nbits)
 {
-	const int nbits_max = (int)(~0U >> (ENTROPY_SHIFT + 1));
+	const int nbits_max = r->poolinfo->poolwords * 32;
 
 	if (nbits < 0)
 		return -EINVAL;
@@ -963,7 +964,6 @@ static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
 struct timer_rand_state {
 	cycles_t last_time;
 	long last_delta, last_delta2;
-	unsigned dont_count_entropy:1;
 };
 
 #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
@@ -1029,35 +1029,33 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
 	 * We take into account the first, second and third-order deltas
 	 * in order to make our estimate.
 	 */
+	delta = sample.jiffies - state->last_time;
+	state->last_time = sample.jiffies;
+
+	delta2 = delta - state->last_delta;
+	state->last_delta = delta;
+
+	delta3 = delta2 - state->last_delta2;
+	state->last_delta2 = delta2;
+
+	if (delta < 0)
+		delta = -delta;
+	if (delta2 < 0)
+		delta2 = -delta2;
+	if (delta3 < 0)
+		delta3 = -delta3;
+	if (delta > delta2)
+		delta = delta2;
+	if (delta > delta3)
+		delta = delta3;
 
-	if (!state->dont_count_entropy) {
-		delta = sample.jiffies - state->last_time;
-		state->last_time = sample.jiffies;
-
-		delta2 = delta - state->last_delta;
-		state->last_delta = delta;
-
-		delta3 = delta2 - state->last_delta2;
-		state->last_delta2 = delta2;
-
-		if (delta < 0)
-			delta = -delta;
-		if (delta2 < 0)
-			delta2 = -delta2;
-		if (delta3 < 0)
-			delta3 = -delta3;
-		if (delta > delta2)
-			delta = delta2;
-		if (delta > delta3)
-			delta = delta3;
+	/*
+	 * delta is now minimum absolute delta.
+	 * Round down by 1 bit on general principles,
+	 * and limit entropy entimate to 12 bits.
+	 */
+	credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
 
-		/*
-		 * delta is now minimum absolute delta.
-		 * Round down by 1 bit on general principles,
-		 * and limit entropy entimate to 12 bits.
-		 */
-		credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
-	}
 	preempt_enable();
 }
 

include/linux/random.h

@@ -85,10 +85,8 @@ static inline unsigned long get_random_canary(void)
 static inline int get_random_bytes_wait(void *buf, int nbytes)
 {
 	int ret = wait_for_random_bytes();
-	if (unlikely(ret))
-		return ret;
 	get_random_bytes(buf, nbytes);
-	return 0;
+	return ret;
 }
 
 #define declare_get_random_var_wait(var) \