Merge tag 'random-6.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:

 - Dynamically allocate cpumasks off of the stack if the kernel is
   configured for a lot of CPUs, to handle a -Wframe-larger-than case

 - The removal of next_pseudo_random32() after the last user was
   switched over to the prandom interface

 - The removal of get_random_u{8,16,32,64}_wait() functions, as there
   were no users of those at all

 - Some house keeping changes - a few grammar cleanups in the
   comments, system_unbound_wq was renamed to system_dfl_wq, and
   static_key_initialized no longer needs to be checked

* tag 'random-6.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  random: complete sentence of comment
  random: drop check for static_key_initialized
  random: remove unused get_random_var_wait functions
  random: replace use of system_unbound_wq with system_dfl_wq
  random: use offstack cpumask when necessary
  prandom: remove next_pseudo_random32
  media: vivid: use prandom
  random: add missing words in function comments

drivers/char/random.c

@@ -259,8 +259,8 @@ static void crng_reseed(struct work_struct *work)
 	u8 key[CHACHA_KEY_SIZE];
 
 	/* Immediately schedule the next reseeding, so that it fires sooner rather than later. */
-	if (likely(system_unbound_wq))
+	if (likely(system_dfl_wq))
-		queue_delayed_work(system_unbound_wq, &next_reseed, crng_reseed_interval());
+		queue_delayed_work(system_dfl_wq, &next_reseed, crng_reseed_interval());
 
 	extract_entropy(key, sizeof(key));
 
@@ -427,7 +427,7 @@ static void _get_random_bytes(void *buf, size_t len)
 
 /*
  * This returns random bytes in arbitrary quantities. The quality of the
- * random bytes is good as /dev/urandom. In order to ensure that the
+ * random bytes is as good as /dev/urandom. In order to ensure that the
  * randomness provided by this function is okay, the function
  * wait_for_random_bytes() should be called and return 0 at least once
  * at any point prior.
@@ -491,7 +491,7 @@ out_zero_chacha:
 
 /*
  * Batched entropy returns random integers. The quality of the random
- * number is good as /dev/urandom. In order to ensure that the randomness
+ * number is as good as /dev/urandom. In order to ensure that the randomness
  * provided by this function is okay, the function wait_for_random_bytes()
  * should be called and return 0 at least once at any point prior.
  */
@@ -741,8 +741,8 @@ static void __cold _credit_init_bits(size_t bits)
 
 	if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
 		crng_reseed(NULL); /* Sets crng_init to CRNG_READY under base_crng.lock. */
-		if (static_key_initialized && system_unbound_wq)
+		if (system_dfl_wq)
-			queue_work(system_unbound_wq, &set_ready);
+			queue_work(system_dfl_wq, &set_ready);
 		atomic_notifier_call_chain(&random_ready_notifier, 0, NULL);
 #ifdef CONFIG_VDSO_GETRANDOM
 		WRITE_ONCE(vdso_k_rng_data->is_ready, true);
@@ -794,7 +794,7 @@ static void __cold _credit_init_bits(size_t bits)
  *
  * add_bootloader_randomness() is called by bootloader drivers, such as EFI
  * and device tree, and credits its input depending on whether or not the
- * command line option 'random.trust_bootloader'.
+ * command line option 'random.trust_bootloader' is set.
  *
  * add_vmfork_randomness() adds a unique (but not necessarily secret) ID
  * representing the current instance of a VM to the pool, without crediting,
@@ -915,9 +915,8 @@ void __init random_init(void)
 	add_latent_entropy();
 
 	/*
-	 * If we were initialized by the cpu or bootloader before jump labels
+	 * If we were initialized by the cpu or bootloader before workqueues
-	 * or workqueues are initialized, then we should enable the static
+	 * are initialized, then we should enable the static branch here.
-	 * branch here, where it's guaranteed that these have been initialized.
 	 */
 	if (!static_branch_likely(&crng_is_ready) && crng_init >= CRNG_READY)
 		crng_set_ready(NULL);
@@ -1296,6 +1295,7 @@ static void __cold try_to_generate_entropy(void)
 	struct entropy_timer_state *stack = PTR_ALIGN((void *)stack_bytes, SMP_CACHE_BYTES);
 	unsigned int i, num_different = 0;
 	unsigned long last = random_get_entropy();
+	cpumask_var_t timer_cpus;
 	int cpu = -1;
 
 	for (i = 0; i < NUM_TRIAL_SAMPLES - 1; ++i) {
@@ -1310,13 +1310,15 @@ static void __cold try_to_generate_entropy(void)
 
 	atomic_set(&stack->samples, 0);
 	timer_setup_on_stack(&stack->timer, entropy_timer, 0);
+	if (!alloc_cpumask_var(&timer_cpus, GFP_KERNEL))
+		goto out;
+
 	while (!crng_ready() && !signal_pending(current)) {
 		/*
 		 * Check !timer_pending() and then ensure that any previous callback has finished
 		 * executing by checking timer_delete_sync_try(), before queueing the next one.
 		 */
 		if (!timer_pending(&stack->timer) && timer_delete_sync_try(&stack->timer) >= 0) {
-			struct cpumask timer_cpus;
 			unsigned int num_cpus;
 
 			/*
@@ -1326,19 +1328,19 @@ static void __cold try_to_generate_entropy(void)
 			preempt_disable();
 
 			/* Only schedule callbacks on timer CPUs that are online. */
-			cpumask_and(&timer_cpus, housekeeping_cpumask(HK_TYPE_TIMER), cpu_online_mask);
+			cpumask_and(timer_cpus, housekeeping_cpumask(HK_TYPE_TIMER), cpu_online_mask);
-			num_cpus = cpumask_weight(&timer_cpus);
+			num_cpus = cpumask_weight(timer_cpus);
 			/* In very bizarre case of misconfiguration, fallback to all online. */
 			if (unlikely(num_cpus == 0)) {
-				timer_cpus = *cpu_online_mask;
+				*timer_cpus = *cpu_online_mask;
-				num_cpus = cpumask_weight(&timer_cpus);
+				num_cpus = cpumask_weight(timer_cpus);
 			}
 
 			/* Basic CPU round-robin, which avoids the current CPU. */
 			do {
-				cpu = cpumask_next(cpu, &timer_cpus);
+				cpu = cpumask_next(cpu, timer_cpus);
 				if (cpu >= nr_cpu_ids)
-					cpu = cpumask_first(&timer_cpus);
+					cpu = cpumask_first(timer_cpus);
 			} while (cpu == smp_processor_id() && num_cpus > 1);
 
 			/* Expiring the timer at `jiffies` means it's the next tick. */
@@ -1354,6 +1356,8 @@ static void __cold try_to_generate_entropy(void)
 	}
 	mix_pool_bytes(&stack->entropy, sizeof(stack->entropy));
 
+	free_cpumask_var(timer_cpus);
+out:
 	timer_delete_sync(&stack->timer);
 	timer_destroy_on_stack(&stack->timer);
 }

drivers/media/test-drivers/vivid/vivid-vid-cap.c

@@ -302,8 +302,10 @@ void vivid_update_quality(struct vivid_dev *dev)
 	 */
 	freq_modulus = (dev->tv_freq - 676 /* (43.25-1) * 16 */) % (6 * 16);
 	if (freq_modulus > 2 * 16) {
+		struct rnd_state prng;
+		prandom_seed_state(&prng, dev->tv_freq ^ 0x55);
 		tpg_s_quality(&dev->tpg, TPG_QUAL_NOISE,
-			next_pseudo_random32(dev->tv_freq ^ 0x55) & 0x3f);
+			prandom_u32_state(&prng) & 0x3f);
 		return;
 	}
 	if (freq_modulus < 12 /*0.75 * 16*/ || freq_modulus > 20 /*1.25 * 16*/)

include/linux/prandom.h

@@ -47,10 +47,4 @@ static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
 	state->s4 = __seed(i, 128U);
 }
 
-/* Pseudo random number generator from numerical recipes. */
-static inline u32 next_pseudo_random32(u32 seed)
-{
-	return seed * 1664525 + 1013904223;
-}
-
 #endif

include/linux/random.h

@@ -130,21 +130,6 @@ static inline int get_random_bytes_wait(void *buf, size_t nbytes)
 	return ret;
 }
 
-#define declare_get_random_var_wait(name, ret_type) \
-	static inline int get_random_ ## name ## _wait(ret_type *out) { \
-		int ret = wait_for_random_bytes(); \
-		if (unlikely(ret)) \
-			return ret; \
-		*out = get_random_ ## name(); \
-		return 0; \
-	}
-declare_get_random_var_wait(u8, u8)
-declare_get_random_var_wait(u16, u16)
-declare_get_random_var_wait(u32, u32)
-declare_get_random_var_wait(u64, u32)
-declare_get_random_var_wait(long, unsigned long)
-#undef declare_get_random_var
-
 #ifdef CONFIG_SMP
 int random_prepare_cpu(unsigned int cpu);
 int random_online_cpu(unsigned int cpu);