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

5 files changed, 7 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index cd75b0ca2555..845023c14eb3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2424,7 +2424,7 @@ gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv,
 	/* Check whether the file_priv has already selected one ring. */
 	if ((int)file_priv->bsd_engine < 0)
 		file_priv->bsd_engine =
-			get_random_int() % num_vcs_engines(dev_priv);
+			prandom_u32_max(num_vcs_engines(dev_priv));
 
 	return file_priv->bsd_engine;
 }
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 329ff75b80b9..7bd1861ddbdf 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -137,12 +137,12 @@ static u64 random_offset(u64 start, u64 end, u64 len, u64 align)
 	range = round_down(end - len, align) - round_up(start, align);
 	if (range) {
 		if (sizeof(unsigned long) == sizeof(u64)) {
-			addr = get_random_long();
+			addr = get_random_u64();
 		} else {
-			addr = get_random_int();
+			addr = get_random_u32();
 			if (range > U32_MAX) {
 				addr <<= 32;
-				addr |= get_random_int();
+				addr |= get_random_u32();
 			}
 		}
 		div64_u64_rem(addr, range, &addr);
diff --git a/drivers/gpu/drm/i915/selftests/i915_selftest.c b/drivers/gpu/drm/i915/selftests/i915_selftest.c
index c4e932368b37..39da0fb0d6d2 100644
--- a/drivers/gpu/drm/i915/selftests/i915_selftest.c
+++ b/drivers/gpu/drm/i915/selftests/i915_selftest.c
@@ -135,7 +135,7 @@ static int __run_selftests(const char *name,
 	int err = 0;
 
 	while (!i915_selftest.random_seed)
-		i915_selftest.random_seed = get_random_int();
+		i915_selftest.random_seed = get_random_u32();
 
 	i915_selftest.timeout_jiffies =
 		i915_selftest.timeout_ms ?
diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c b/drivers/gpu/drm/tests/drm_buddy_test.c
index 7a2b2d6bc3fe..62f69589a72d 100644
--- a/drivers/gpu/drm/tests/drm_buddy_test.c
+++ b/drivers/gpu/drm/tests/drm_buddy_test.c
@@ -729,7 +729,7 @@ static void drm_test_buddy_alloc_limit(struct kunit *test)
 static int drm_buddy_init_test(struct kunit *test)
 {
 	while (!random_seed)
-		random_seed = get_random_int();
+		random_seed = get_random_u32();
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/tests/drm_mm_test.c b/drivers/gpu/drm/tests/drm_mm_test.c
index 659d1af4dca7..c4b66eeae203 100644
--- a/drivers/gpu/drm/tests/drm_mm_test.c
+++ b/drivers/gpu/drm/tests/drm_mm_test.c
@@ -2212,7 +2212,7 @@ err_nodes:
 static int drm_mm_init_test(struct kunit *test)
 {
 	while (!random_seed)
-		random_seed = get_random_int();
+		random_seed = get_random_u32();
 
 	return 0;
 }