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| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-10-01 01:31:00 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-10-24 10:58:07 +0300 |
| commit | ccc9abee86c5cf7e0a1805ec3fbab6c4566a2413 (patch) | |
| tree | 12cbaead748fa96a736c36e252f68b3871c61392 | |
| parent | 371fa5129af53a79f6dddc90fe5bb0825cbe72a4 (diff) | |
| download | linux-ccc9abee86c5cf7e0a1805ec3fbab6c4566a2413.tar.xz | |
random: schedule jitter credit for next jiffy, not in two jiffies
[ Upstream commit 122733471384be8c23f019fbbd46bdf7be561dcd ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/char/random.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 8dfb28d5ae3f..5defbc479a5c 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1178,7 +1178,7 @@ 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(); @@ -1197,7 +1197,7 @@ 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(); |