Merge tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull more random number generator updates from Jason Donenfeld:
 "This time with some large scale treewide cleanups.

  The intent of this pull is to clean up the way callers fetch random
  integers. The current rules for doing this right are:

   - If you want a secure or an insecure random u64, use get_random_u64()

   - If you want a secure or an insecure random u32, use get_random_u32()

     The old function prandom_u32() has been deprecated for a while
     now and is just a wrapper around get_random_u32(). Same for
     get_random_int().

   - If you want a secure or an insecure random u16, use get_random_u16()

   - If you want a secure or an insecure random u8, use get_random_u8()

   - If you want secure or insecure random bytes, use get_random_bytes().

     The old function prandom_bytes() has been deprecated for a while
     now and has long been a wrapper around get_random_bytes()

   - If you want a non-uniform random u32, u16, or u8 bounded by a
     certain open interval maximum, use prandom_u32_max()

     I say "non-uniform", because it doesn't do any rejection sampling
     or divisions. Hence, it stays within the prandom_*() namespace, not
     the get_random_*() namespace.

     I'm currently investigating a "uniform" function for 6.2. We'll see
     what comes of that.

  By applying these rules uniformly, we get several benefits:

   - By using prandom_u32_max() with an upper-bound that the compiler
     can prove at compile-time is ≤65536 or ≤256, internally
     get_random_u16() or get_random_u8() is used, which wastes fewer
     batched random bytes, and hence has higher throughput.

   - By using prandom_u32_max() instead of %, when the upper-bound is
     not a constant, division is still avoided, because
     prandom_u32_max() uses a faster multiplication-based trick instead.

   - By using get_random_u16() or get_random_u8() in cases where the
     return value is intended to indeed be a u16 or a u8, we waste fewer
     batched random bytes, and hence have higher throughput.

  This series was originally done by hand while I was on an airplane
  without Internet. Later, Kees and I worked on retroactively figuring
  out what could be done with Coccinelle and what had to be done
  manually, and then we split things up based on that.

  So while this touches a lot of files, the actual amount of code that's
  hand fiddled is comfortably small"

* tag 'random-6.1-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  prandom: remove unused functions
  treewide: use get_random_bytes() when possible
  treewide: use get_random_u32() when possible
  treewide: use get_random_{u8,u16}() when possible, part 2
  treewide: use get_random_{u8,u16}() when possible, part 1
  treewide: use prandom_u32_max() when possible, part 2
  treewide: use prandom_u32_max() when possible, part 1

17 files changed, 38 insertions, 47 deletions

diff --git a/lib/cmdline_kunit.c b/lib/cmdline_kunit.c
index a72a2c16066e..d4572dbc9145 100644
--- a/lib/cmdline_kunit.c
+++ b/lib/cmdline_kunit.c
@@ -76,7 +76,7 @@ static void cmdline_test_lead_int(struct kunit *test)
 		int rc = cmdline_test_values[i];
 		int offset;
 
-		sprintf(in, "%u%s", get_random_int() % 256, str);
+		sprintf(in, "%u%s", get_random_u8(), str);
 		/* Only first '-' after the number will advance the pointer */
 		offset = strlen(in) - strlen(str) + !!(rc == 2);
 		cmdline_do_one_test(test, in, rc, offset);
@@ -94,7 +94,7 @@ static void cmdline_test_tail_int(struct kunit *test)
 		int rc = strcmp(str, "") ? (strcmp(str, "-") ? 0 : 1) : 1;
 		int offset;
 
-		sprintf(in, "%s%u", str, get_random_int() % 256);
+		sprintf(in, "%s%u", str, get_random_u8());
 		/*
 		 * Only first and leading '-' not followed by integer
 		 * will advance the pointer.
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 423784d9c058..96e092de5b72 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -139,7 +139,7 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
 			return false;
 	}
 
-	if (attr->probability <= prandom_u32() % 100)
+	if (attr->probability <= prandom_u32_max(100))
 		return false;
 
 	if (!fail_stacktrace(attr))
diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
index 10754586403b..7c3c011abd29 100644
--- a/lib/find_bit_benchmark.c
+++ b/lib/find_bit_benchmark.c
@@ -174,8 +174,8 @@ static int __init find_bit_test(void)
 	bitmap_zero(bitmap2, BITMAP_LEN);
 
 	while (nbits--) {
-		__set_bit(prandom_u32() % BITMAP_LEN, bitmap);
-		__set_bit(prandom_u32() % BITMAP_LEN, bitmap2);
+		__set_bit(prandom_u32_max(BITMAP_LEN), bitmap);
+		__set_bit(prandom_u32_max(BITMAP_LEN), bitmap2);
 	}
 
 	test_find_next_bit(bitmap, BITMAP_LEN);
diff --git a/lib/kobject.c b/lib/kobject.c
index 5f0e71ab292c..a0b2dbfcfa23 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -694,7 +694,7 @@ static void kobject_release(struct kref *kref)
 {
 	struct kobject *kobj = container_of(kref, struct kobject, kref);
 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
-	unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
+	unsigned long delay = HZ + HZ * prandom_u32_max(4);
 	pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
 		 kobject_name(kobj), kobj, __func__, kobj->parent, delay);
 	INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
diff --git a/lib/random32.c b/lib/random32.c
index d5d9029362cb..32060b852668 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -47,7 +47,7 @@
  *	@state: pointer to state structure holding seeded state.
  *
  *	This is used for pseudo-randomness with no outside seeding.
- *	For more random results, use prandom_u32().
+ *	For more random results, use get_random_u32().
  */
 u32 prandom_u32_state(struct rnd_state *state)
 {
@@ -69,7 +69,7 @@ EXPORT_SYMBOL(prandom_u32_state);
  *	@bytes: the requested number of bytes
  *
  *	This is used for pseudo-randomness with no outside seeding.
- *	For more random results, use prandom_bytes().
+ *	For more random results, use get_random_bytes().
  */
 void prandom_bytes_state(struct rnd_state *state, void *buf, size_t bytes)
 {
diff --git a/lib/reed_solomon/test_rslib.c b/lib/reed_solomon/test_rslib.c
index d9d1c33aebda..848e7eb5da92 100644
--- a/lib/reed_solomon/test_rslib.c
+++ b/lib/reed_solomon/test_rslib.c
@@ -164,7 +164,7 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
 
 	/* Load c with random data and encode */
 	for (i = 0; i < dlen; i++)
-		c[i] = prandom_u32() & nn;
+		c[i] = get_random_u32() & nn;
 
 	memset(c + dlen, 0, nroots * sizeof(*c));
 	encode_rs16(rs, c, dlen, c + dlen, 0);
@@ -178,12 +178,12 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
 	for (i = 0; i < errs; i++) {
 		do {
 			/* Error value must be nonzero */
-			errval = prandom_u32() & nn;
+			errval = get_random_u32() & nn;
 		} while (errval == 0);
 
 		do {
 			/* Must not choose the same location twice */
-			errloc = prandom_u32() % len;
+			errloc = prandom_u32_max(len);
 		} while (errlocs[errloc] != 0);
 
 		errlocs[errloc] = 1;
@@ -194,19 +194,19 @@ static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
 	for (i = 0; i < eras; i++) {
 		do {
 			/* Must not choose the same location twice */
-			errloc = prandom_u32() % len;
+			errloc = prandom_u32_max(len);
 		} while (errlocs[errloc] != 0);
 
 		derrlocs[i] = errloc;
 
-		if (ewsc && (prandom_u32() & 1)) {
+		if (ewsc && prandom_u32_max(2)) {
 			/* Erasure with the symbol intact */
 			errlocs[errloc] = 2;
 		} else {
 			/* Erasure with corrupted symbol */
 			do {
 				/* Error value must be nonzero */
-				errval = prandom_u32() & nn;
+				errval = get_random_u32() & nn;
 			} while (errval == 0);
 
 			errlocs[errloc] = 1;
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index a8108a962dfd..7280ae8ca88c 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -21,7 +21,7 @@ static int init_alloc_hint(struct sbitmap *sb, gfp_t flags)
 		int i;
 
 		for_each_possible_cpu(i)
-			*per_cpu_ptr(sb->alloc_hint, i) = prandom_u32() % depth;
+			*per_cpu_ptr(sb->alloc_hint, i) = prandom_u32_max(depth);
 	}
 	return 0;
 }
@@ -33,7 +33,7 @@ static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,
 
 	hint = this_cpu_read(*sb->alloc_hint);
 	if (unlikely(hint >= depth)) {
-		hint = depth ? prandom_u32() % depth : 0;
+		hint = depth ? prandom_u32_max(depth) : 0;
 		this_cpu_write(*sb->alloc_hint, hint);
 	}
 
diff --git a/lib/test-string_helpers.c b/lib/test-string_helpers.c
index 437d8e6b7cb1..86fadd3ba08c 100644
--- a/lib/test-string_helpers.c
+++ b/lib/test-string_helpers.c
@@ -587,7 +587,7 @@ static int __init test_string_helpers_init(void)
 	for (i = 0; i < UNESCAPE_ALL_MASK + 1; i++)
 		test_string_unescape("unescape", i, false);
 	test_string_unescape("unescape inplace",
-			     get_random_int() % (UNESCAPE_ANY + 1), true);
+			     prandom_u32_max(UNESCAPE_ANY + 1), true);
 
 	/* Without dictionary */
 	for (i = 0; i < ESCAPE_ALL_MASK + 1; i++)
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index ed70637a2ffa..e0381b3ec410 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -145,7 +145,7 @@ static unsigned long get_ftrace_location(void *func)
 static int fprobe_test_init(struct kunit *test)
 {
 	do {
-		rand1 = prandom_u32();
+		rand1 = get_random_u32();
 	} while (rand1 <= div_factor);
 
 	target = fprobe_selftest_target;
diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c
index 5144899d3c6b..0927f44cd478 100644
--- a/lib/test_hexdump.c
+++ b/lib/test_hexdump.c
@@ -149,7 +149,7 @@ static void __init test_hexdump(size_t len, int rowsize, int groupsize,
 static void __init test_hexdump_set(int rowsize, bool ascii)
 {
 	size_t d = min_t(size_t, sizeof(data_b), rowsize);
-	size_t len = get_random_int() % d + 1;
+	size_t len = prandom_u32_max(d) + 1;
 
 	test_hexdump(len, rowsize, 4, ascii);
 	test_hexdump(len, rowsize, 2, ascii);
@@ -208,11 +208,11 @@ static void __init test_hexdump_overflow(size_t buflen, size_t len,
 static void __init test_hexdump_overflow_set(size_t buflen, bool ascii)
 {
 	unsigned int i = 0;
-	int rs = (get_random_int() % 2 + 1) * 16;
+	int rs = (prandom_u32_max(2) + 1) * 16;
 
 	do {
 		int gs = 1 << i;
-		size_t len = get_random_int() % rs + gs;
+		size_t len = prandom_u32_max(rs) + gs;
 
 		test_hexdump_overflow(buflen, rounddown(len, gs), rs, gs, ascii);
 	} while (i++ < 3);
@@ -223,11 +223,11 @@ static int __init test_hexdump_init(void)
 	unsigned int i;
 	int rowsize;
 
-	rowsize = (get_random_int() % 2 + 1) * 16;
+	rowsize = (prandom_u32_max(2) + 1) * 16;
 	for (i = 0; i < 16; i++)
 		test_hexdump_set(rowsize, false);
 
-	rowsize = (get_random_int() % 2 + 1) * 16;
+	rowsize = (prandom_u32_max(2) + 1) * 16;
 	for (i = 0; i < 16; i++)
 		test_hexdump_set(rowsize, true);
 
diff --git a/lib/test_kprobes.c b/lib/test_kprobes.c
index a5edc2ebc947..eeb1d728d974 100644
--- a/lib/test_kprobes.c
+++ b/lib/test_kprobes.c
@@ -341,7 +341,7 @@ static int kprobes_test_init(struct kunit *test)
 	stacktrace_driver = kprobe_stacktrace_driver;
 
 	do {
-		rand1 = prandom_u32();
+		rand1 = get_random_u32();
 	} while (rand1 <= div_factor);
 	return 0;
 }
diff --git a/lib/test_list_sort.c b/lib/test_list_sort.c
index ade7a1ea0c8e..19ff229b9c3a 100644
--- a/lib/test_list_sort.c
+++ b/lib/test_list_sort.c
@@ -71,7 +71,7 @@ static void list_sort_test(struct kunit *test)
 		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, el);
 
 		 /* force some equivalencies */
-		el->value = prandom_u32() % (TEST_LIST_LEN / 3);
+		el->value = prandom_u32_max(TEST_LIST_LEN / 3);
 		el->serial = i;
 		el->poison1 = TEST_POISON1;
 		el->poison2 = TEST_POISON2;
diff --git a/lib/test_min_heap.c b/lib/test_min_heap.c
index d19c8080fd4d..7b01b4387cfb 100644
--- a/lib/test_min_heap.c
+++ b/lib/test_min_heap.c
@@ -83,7 +83,7 @@ static __init int test_heapify_all(bool min_heap)
 	/* Test with randomly generated values. */
 	heap.nr = ARRAY_SIZE(values);
 	for (i = 0; i < heap.nr; i++)
-		values[i] = get_random_int();
+		values[i] = get_random_u32();
 
 	min_heapify_all(&heap, &funcs);
 	err += pop_verify_heap(min_heap, &heap, &funcs);
@@ -116,7 +116,7 @@ static __init int test_heap_push(bool min_heap)
 
 	/* Test with randomly generated values. */
 	while (heap.nr < heap.size) {
-		temp = get_random_int();
+		temp = get_random_u32();
 		min_heap_push(&heap, &temp, &funcs);
 	}
 	err += pop_verify_heap(min_heap, &heap, &funcs);
@@ -158,7 +158,7 @@ static __init int test_heap_pop_push(bool min_heap)
 
 	/* Test with randomly generated values. */
 	for (i = 0; i < ARRAY_SIZE(data); i++) {
-		temp = get_random_int();
+		temp = get_random_u32();
 		min_heap_pop_push(&heap, &temp, &funcs);
 	}
 	err += pop_verify_heap(min_heap, &heap, &funcs);
diff --git a/lib/test_objagg.c b/lib/test_objagg.c
index da137939a410..c0c957c50635 100644
--- a/lib/test_objagg.c
+++ b/lib/test_objagg.c
@@ -157,7 +157,7 @@ static int test_nodelta_obj_get(struct world *world, struct objagg *objagg,
 	int err;
 
 	if (should_create_root)
-		prandom_bytes(world->next_root_buf,
+		get_random_bytes(world->next_root_buf,
 			      sizeof(world->next_root_buf));
 
 	objagg_obj = world_obj_get(world, objagg, key_id);
diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index 5a1dd4736b56..b358a74ed7ed 100644
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -291,7 +291,7 @@ static int __init test_rhltable(unsigned int entries)
 	if (WARN_ON(err))
 		goto out_free;
 
-	k = prandom_u32();
+	k = get_random_u32();
 	ret = 0;
 	for (i = 0; i < entries; i++) {
 		rhl_test_objects[i].value.id = k;
@@ -369,12 +369,12 @@ static int __init test_rhltable(unsigned int entries)
 	pr_info("test %d random rhlist add/delete operations\n", entries);
 	for (j = 0; j < entries; j++) {
 		u32 i = prandom_u32_max(entries);
-		u32 prand = prandom_u32();
+		u32 prand = get_random_u32();
 
 		cond_resched();
 
 		if (prand == 0)
-			prand = prandom_u32();
+			prand = get_random_u32();
 
 		if (prand & 1) {
 			prand >>= 1;
diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
index 4f2f2d1bac56..cf7780572f5b 100644
--- a/lib/test_vmalloc.c
+++ b/lib/test_vmalloc.c
@@ -80,7 +80,7 @@ static int random_size_align_alloc_test(void)
 	int i;
 
 	for (i = 0; i < test_loop_count; i++) {
-		rnd = prandom_u32();
+		rnd = get_random_u8();
 
 		/*
 		 * Maximum 1024 pages, if PAGE_SIZE is 4096.
@@ -151,9 +151,7 @@ static int random_size_alloc_test(void)
 	int i;
 
 	for (i = 0; i < test_loop_count; i++) {
-		n = prandom_u32();
-		n = (n % 100) + 1;
-
+		n = prandom_u32_max(100) + 1;
 		p = vmalloc(n * PAGE_SIZE);
 
 		if (!p)
@@ -293,16 +291,12 @@ pcpu_alloc_test(void)
 		return -1;
 
 	for (i = 0; i < 35000; i++) {
-		unsigned int r;
-
-		r = prandom_u32();
-		size = (r % (PAGE_SIZE / 4)) + 1;
+		size = prandom_u32_max(PAGE_SIZE / 4) + 1;
 
 		/*
 		 * Maximum PAGE_SIZE
 		 */
-		r = prandom_u32();
-		align = 1 << ((r % 11) + 1);
+		align = 1 << (prandom_u32_max(11) + 1);
 
 		pcpu[i] = __alloc_percpu(size, align);
 		if (!pcpu[i])
@@ -393,14 +387,11 @@ static struct test_driver {
 
 static void shuffle_array(int *arr, int n)
 {
-	unsigned int rnd;
 	int i, j;
 
 	for (i = n - 1; i > 0; i--)  {
-		rnd = prandom_u32();
-
 		/* Cut the range. */
-		j = rnd % i;
+		j = prandom_u32_max(i);
 
 		/* Swap indexes. */
 		swap(arr[i], arr[j]);
diff --git a/lib/uuid.c b/lib/uuid.c
index 562d53977cab..e309b4c5be3d 100644
--- a/lib/uuid.c
+++ b/lib/uuid.c
@@ -52,7 +52,7 @@ EXPORT_SYMBOL(generate_random_guid);
 
 static void __uuid_gen_common(__u8 b[16])
 {
-	prandom_bytes(b, 16);
+	get_random_bytes(b, 16);
 	/* reversion 0b10 */
 	b[8] = (b[8] & 0x3F) | 0x80;
 }