Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit feee7697 authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
Browse files

random: eliminate redundant new_rotate variable 



- eliminate new_rotate
- move input_rotate masking
- simplify input_rotate update
- move input_rotate update to end of inner loop for readability

Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 43358209

drivers/char/random.c

+10 −12
Original line number Diff line number Diff line
@@ -455,7 +455,7 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in, 
		0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,

		0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };

	unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;

	int new_rotate, input_rotate;

	int input_rotate;

	int wordmask = r->poolinfo->poolwords - 1;

	__u32 w, next_w;

	unsigned long flags;
@@ -474,20 +474,10 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in, 
	add_ptr = r->add_ptr;



	while (nwords--) {

		w = rol32(next_w, input_rotate);

		w = rol32(next_w, input_rotate & 31);

		if (nwords > 0)

			next_w = *in++;

		i = add_ptr = (add_ptr - 1) & wordmask;

		/*

		 * Normally, we add 7 bits of rotation to the pool.

		 * At the beginning of the pool, add an extra 7 bits

		 * rotation, so that successive passes spread the

		 * input bits across the pool evenly.

		 */

		new_rotate = input_rotate + 14;

		if (i)

			new_rotate = input_rotate + 7;

		input_rotate = new_rotate & 31;



		/* XOR in the various taps */

		w ^= r->pool[(i + tap1) & wordmask];
@@ -497,6 +487,14 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in, 
		w ^= r->pool[(i + tap5) & wordmask];

		w ^= r->pool[i];

		r->pool[i] = (w >> 3) ^ twist_table[w & 7];



		/*

		 * Normally, we add 7 bits of rotation to the pool.

		 * At the beginning of the pool, add an extra 7 bits

		 * rotation, so that successive passes spread the

		 * input bits across the pool evenly.

		 */

		input_rotate += i ? 7 : 14;

	}



	r->input_rotate = input_rotate;