From: Ingo Molnar <[email protected]>
No need to keep preemption disabled across the whole function.
mix_pool_bytes() uses a spin_lock() to protect the pool and there are
other places like write_pool() whhich invoke mix_pool_bytes() without
disabling preemption.
credit_entropy_bits() is invoked from other places like
add_hwgenerator_randomness() without disabling preemption.
Before commit 95b709b6be49 ("random: drop trickle mode") the function
used __this_cpu_inc_return() which would require disabled preemption.
The preempt_disable() section was added in commit 43d5d3018c37 ("[PATCH]
random driver preempt robustness", history tree). It was claimed that
the code relied on "vt_ioctl() being called under BKL".
Cc: "Theodore Ts'o" <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
[bigeasy: enhance the commit message]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
---
drivers/char/random.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index cd888d4ee605..e43690977b29 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1122,8 +1122,6 @@ static void add_timer_randomness(struct timer_rand_state
*state, unsigned num)
} sample;
long delta, delta2, delta3;
- preempt_disable();
-
sample.jiffies = jiffies;
sample.cycles = random_get_entropy();
sample.num = num;
@@ -1161,8 +1159,6 @@ static void add_timer_randomness(struct timer_rand_state
*state, unsigned num)
* and limit entropy entimate to 12 bits.
*/
credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
-
- preempt_enable();
}
void add_input_randomness(unsigned int type, unsigned int code,
--
2.18.0
