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authorJason A. Donenfeld <Jason@zx2c4.com>2022-10-01 01:31:00 +0300
committerJason A. Donenfeld <Jason@zx2c4.com>2022-10-01 13:04:21 +0300
commit122733471384be8c23f019fbbd46bdf7be561dcd (patch)
tree9f8678593ea57807688d88acc212ecbbc6543ae3 /drivers/char/random.c
parent4c95236a335d8b62aa8dbd587bed6a5f30d8265a (diff)
downloadlinux-122733471384be8c23f019fbbd46bdf7be561dcd.tar.xz
random: schedule jitter credit for next jiffy, not in two jiffies
Counterintuitively, mod_timer(..., jiffies + 1) will cause the timer to fire not in the next jiffy, but in two jiffies. The way to cause the timer to fire in the next jiffy is with mod_timer(..., jiffies). Doing so then lets us bump the upper bound back up again. Fixes: 50ee7529ec45 ("random: try to actively add entropy rather than passively wait for it") Fixes: 829d680e82a9 ("random: cap jitter samples per bit to factor of HZ") Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Sultan Alsawaf <sultan@kerneltoast.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 64ee16ffb8b7..fdf15f5c87dd 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1205,7 +1205,7 @@ static void __cold entropy_timer(struct timer_list *timer)
*/
static void __cold try_to_generate_entropy(void)
{
- enum { NUM_TRIAL_SAMPLES = 8192, MAX_SAMPLES_PER_BIT = HZ / 30 };
+ enum { NUM_TRIAL_SAMPLES = 8192, MAX_SAMPLES_PER_BIT = HZ / 15 };
struct entropy_timer_state stack;
unsigned int i, num_different = 0;
unsigned long last = random_get_entropy();
@@ -1224,7 +1224,7 @@ static void __cold try_to_generate_entropy(void)
timer_setup_on_stack(&stack.timer, entropy_timer, 0);
while (!crng_ready() && !signal_pending(current)) {
if (!timer_pending(&stack.timer))
- mod_timer(&stack.timer, jiffies + 1);
+ mod_timer(&stack.timer, jiffies);
mix_pool_bytes(&stack.entropy, sizeof(stack.entropy));
schedule();
stack.entropy = random_get_entropy();