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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>
This commit is contained in:
Matt Mackall 2008-04-29 01:03:03 -07:00 committed by Linus Torvalds
parent feee76972b
commit 6d38b82740
1 changed files with 2 additions and 6 deletions
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8
drivers/char/random.c
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@ -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 */