[PATCH] random: use proper cycle_t type for random_get_entropy()

From: Jason A. Donenfeld
Date: Thu Feb 24 2022 - 12:39:58 EST


random_get_entropy() returns a cycles_t, not an unsigned long, which is
sometimes 64 bits on various 32-bit platforms, including x86.
Conversely, jiffies is always unsigned long. This commit fixes things to
use cycles_t for fields that use random_get_entropy() and unsigned long
for fields that use jiffies.

Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
drivers/char/random.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 19bf44b9ba0f..4e37b8e2acc1 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1002,7 +1002,7 @@ int __init rand_initialize(void)

/* There is one of these per entropy source */
struct timer_rand_state {
- cycles_t last_time;
+ unsigned long last_time;
long last_delta, last_delta2;
};

@@ -1016,7 +1016,7 @@ struct timer_rand_state {
*/
void add_device_randomness(const void *buf, size_t size)
{
- unsigned long time = random_get_entropy() ^ jiffies;
+ cycles_t time = random_get_entropy() ^ jiffies;
unsigned long flags;

if (crng_init == 0 && size)
@@ -1042,8 +1042,8 @@ EXPORT_SYMBOL(add_device_randomness);
static void add_timer_randomness(struct timer_rand_state *state, unsigned int num)
{
struct {
+ cycles_t cycles;
long jiffies;
- unsigned int cycles;
unsigned int num;
} sample;
long delta, delta2, delta3;
@@ -1356,7 +1356,7 @@ static void entropy_timer(struct timer_list *t)
static void try_to_generate_entropy(void)
{
struct {
- unsigned long now;
+ cycles_t now;
struct timer_list timer;
} stack;

--
2.35.1