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Commit b34fbaa9 authored by Ingo Molnar's avatar Ingo Molnar Committed by Theodore Ts'o
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random: remove preempt disabled region 



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 95b709b6 ("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" <tytso@mit.edu>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
[bigeasy: enhance the commit message]
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 39a8883a

drivers/char/random.c

+0 −4
Original line number Diff line number Diff line
@@ -1131,8 +1131,6 @@ 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;
@@ -1170,8 +1168,6 @@ 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,