[PATCH 4.9 029/264] drivers/char/random.c: remove unused dont_count_entropy

Greg Kroah-Hartman
2022-06-23T16:47:47Z

From: Rasmus Villemoes <linux@rasmusvillemoes.dk>

commit 5e747dd9be54be190dd6ebeebf4a4a01ba765625 upstream.

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>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 55 +++++++++++++++++++++++---------------------------
1 file changed, 26 insertions(+), 29 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1130,7 +1130,6 @@ static ssize_t extract_crng_user(void __
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, };
@@ -1194,35 +1193,33 @@ static void add_timer_randomness(struct
* 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;
+
+ delta2 = delta - state->last_delta;
+ state->last_delta = delta;
+
+ 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;
+
+ /*
+ * 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));

- 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;
-
- 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;
-
- /*
- * 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();
}