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drivers/char/random.c: remove unused dont_count_entropy

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Ever since "random: kill dead extract_state struct" [1], the
dont_count_entropy member of struct timer_rand_state has been
effectively unused. Since it hasn't found a new use in 12 years, it's
probably safe to finally kill it.

[1] Pre-git, https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=c1c48e61c251f57e7a3f1bf11b3c462b2de9dcb5

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Rasmus Villemoes 2018-03-01 00:22:47 +01:00 committed by Theodore Ts'o
parent e8e8a2e47d
commit 5e747dd9be
1 changed files with 22 additions and 25 deletions
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47
drivers/char/random.c
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@ -964,7 +964,6 @@ static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
struct timer_rand_state {
cycles_t last_time;
long last_delta, last_delta2;
unsigned dont_count_entropy:1;
};
#define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
@ -1030,35 +1029,33 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
* We take into account the first, second and third-order deltas
* in order to make our estimate.
*/
delta = sample.jiffies - state->last_time;
state->last_time = sample.jiffies;
if (!state->dont_count_entropy) {
delta = sample.jiffies - state->last_time;
state->last_time = sample.jiffies;
delta2 = delta - state->last_delta;
state->last_delta = delta;
delta2 = delta - state->last_delta;
state->last_delta = delta;
delta3 = delta2 - state->last_delta2;
state->last_delta2 = delta2;
delta3 = delta2 - state->last_delta2;
state->last_delta2 = delta2;
if (delta < 0)
delta = -delta;
if (delta2 < 0)
delta2 = -delta2;
if (delta3 < 0)
delta3 = -delta3;
if (delta > delta2)
delta = delta2;
if (delta > delta3)
delta = delta3;
if (delta < 0)
delta = -delta;
if (delta2 < 0)
delta2 = -delta2;
if (delta3 < 0)
delta3 = -delta3;
if (delta > delta2)
delta = delta2;
if (delta > delta3)
delta = delta3;
/*
* delta is now minimum absolute delta.
* Round down by 1 bit on general principles,
* and limit entropy entimate to 12 bits.
*/
credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
/*
* delta is now minimum absolute delta.
* Round down by 1 bit on general principles,
* and limit entropy entimate to 12 bits.
*/
credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
}
preempt_enable();
}