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: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 12 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 973706e97e77..3823cb2e3b9a 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -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;