random: remove some prefetch logic

The urandom output pool (ie the fast path) fits in one cacheline, so
this is pretty unnecessary. Further, the output path has already
fetched the entire pool to hash it before calling in here.

(This was the only user of prefetch_range in the kernel, and it passed
in words rather than bytes!)

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>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 3823cb2e3b9ac7c302ca1bf9321660200629f4c7..a754132336bad856f3cd849cd3f804328bf7caa2 100644 (file)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -457,7 +457,7 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
        unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;
        int input_rotate;
        int wordmask = r->poolinfo->poolwords - 1;
-       __u32 w, next_w;
+       __u32 w;
        unsigned long flags;
 
        /* Taps are constant, so we can load them without holding r->lock.  */
@@ -466,17 +466,13 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
        tap3 = r->poolinfo->tap3;
        tap4 = r->poolinfo->tap4;
        tap5 = r->poolinfo->tap5;
-       next_w = *in++;
 
        spin_lock_irqsave(&r->lock, flags);
-       prefetch_range(r->pool, wordmask);
        input_rotate = r->input_rotate;
        add_ptr = r->add_ptr;
 
        while (nwords--) {
-               w = rol32(next_w, input_rotate & 31);
-               if (nwords > 0)
-                       next_w = *in++;
+               w = rol32(*in++, input_rotate & 31);
                i = add_ptr = (add_ptr - 1) & wordmask;
 
                /* XOR in the various taps */