diff options
| author | Matt Mackall <mpm@selenic.com> | 2008-04-29 01:03:04 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 08:06:25 -0700 |
| commit | 993ba2114c554c1561a018e5c63a771ec8e1c469 (patch) | |
| tree | 75df2f882845b12b698c305625f01dc6ef227147 /drivers | |
| parent | 6d38b827400d7c02bce391f90d044e4c57d5bc1e (diff) | |
random: simplify add_ptr logic
The add_ptr variable wasn't used in a sensible way, use only i instead.
i got reused later for a different purpose, use j instead.
While we're here, put tap0 first in the tap list and add a comment.
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/char/random.c | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index a754132336b..ba0d7030538 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -454,7 +454,7 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in, static __u32 const twist_table[8] = { 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158, 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 }; - unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5; + unsigned long i, j, tap1, tap2, tap3, tap4, tap5; int input_rotate; int wordmask = r->poolinfo->poolwords - 1; __u32 w; @@ -469,19 +469,21 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in, spin_lock_irqsave(&r->lock, flags); input_rotate = r->input_rotate; - add_ptr = r->add_ptr; + i = r->add_ptr; while (nwords--) { w = rol32(*in++, input_rotate & 31); - i = add_ptr = (add_ptr - 1) & wordmask; + i = (i - 1) & wordmask; /* XOR in the various taps */ + w ^= r->pool[i]; w ^= r->pool[(i + tap1) & wordmask]; w ^= r->pool[(i + tap2) & wordmask]; w ^= r->pool[(i + tap3) & wordmask]; w ^= r->pool[(i + tap4) & wordmask]; w ^= r->pool[(i + tap5) & wordmask]; - w ^= r->pool[i]; + + /* Mix the result back in with a twist */ r->pool[i] = (w >> 3) ^ twist_table[w & 7]; /* @@ -494,14 +496,11 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in, } r->input_rotate = input_rotate; - r->add_ptr = add_ptr; + r->add_ptr = i; - if (out) { - for (i = 0; i < 16; i++) { - out[i] = r->pool[add_ptr]; - add_ptr = (add_ptr - 1) & wordmask; - } - } + if (out) + for (j = 0; j < 16; j++) + out[j] = r->pool[(i - j) & wordmask]; spin_unlock_irqrestore(&r->lock, flags); } |