forked from luck/tmp_suning_uos_patched
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>
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@ -454,7 +454,7 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
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static __u32 const twist_table[8] = {
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0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
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0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
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unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;
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unsigned long i, j, tap1, tap2, tap3, tap4, tap5;
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int input_rotate;
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int wordmask = r->poolinfo->poolwords - 1;
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__u32 w;
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@ -469,19 +469,21 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
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spin_lock_irqsave(&r->lock, flags);
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input_rotate = r->input_rotate;
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add_ptr = r->add_ptr;
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i = r->add_ptr;
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while (nwords--) {
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w = rol32(*in++, input_rotate & 31);
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i = add_ptr = (add_ptr - 1) & wordmask;
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i = (i - 1) & wordmask;
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/* XOR in the various taps */
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w ^= r->pool[i];
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w ^= r->pool[(i + tap1) & wordmask];
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w ^= r->pool[(i + tap2) & wordmask];
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w ^= r->pool[(i + tap3) & wordmask];
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w ^= r->pool[(i + tap4) & wordmask];
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w ^= r->pool[(i + tap5) & wordmask];
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w ^= r->pool[i];
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/* Mix the result back in with a twist */
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r->pool[i] = (w >> 3) ^ twist_table[w & 7];
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/*
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@ -494,14 +496,11 @@ static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
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}
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r->input_rotate = input_rotate;
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r->add_ptr = add_ptr;
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r->add_ptr = i;
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if (out) {
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for (i = 0; i < 16; i++) {
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out[i] = r->pool[add_ptr];
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add_ptr = (add_ptr - 1) & wordmask;
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}
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}
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if (out)
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for (j = 0; j < 16; j++)
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out[j] = r->pool[(i - j) & wordmask];
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spin_unlock_irqrestore(&r->lock, flags);
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}
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