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authorAlexander Duyck <alexander.h.duyck@redhat.com>2015-03-31 14:19:10 -0700
committerDavid S. Miller <davem@davemloft.net>2015-04-03 12:52:29 -0400
commit2e7056c433216f406b90a003aa0ba42e19d3bdcf (patch)
tree9839bafb2d86ac847b062635dca3b60514fb26a8 /include/linux/jhash.h
parent5c5e0ad3f9dca572198f3ad6fbf7dc2e647bcf0c (diff)
jhash: Update jhash_[321]words functions to use correct initval
Looking over the implementation for jhash2 and comparing it to jhash_3words I realized that the two hashes were in fact very different. Doing a bit of digging led me to "The new jhash implementation" in which lookup2 was supposed to have been replaced with lookup3. In reviewing the patch I noticed that jhash2 had originally initialized a and b to JHASH_GOLDENRATIO and c to initval, but after the patch a, b, and c were initialized to initval + (length << 2) + JHASH_INITVAL. However the changes in jhash_3words simply replaced the initialization of a and b with JHASH_INITVAL. This change corrects what I believe was an oversight so that a, b, and c in jhash_3words all have the same value added consisting of initval + (length << 2) + JHASH_INITVAL so that jhash2 and jhash_3words will now produce the same hash result given the same inputs. Fixes: 60d509c823cca ("The new jhash implementation") Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/jhash.h')
-rw-r--r--include/linux/jhash.h17
1 files changed, 11 insertions, 6 deletions
diff --git a/include/linux/jhash.h b/include/linux/jhash.h
index 47cb09edec1a..348c6f47e4cc 100644
--- a/include/linux/jhash.h
+++ b/include/linux/jhash.h
@@ -145,11 +145,11 @@ static inline u32 jhash2(const u32 *k, u32 length, u32 initval)
}
-/* jhash_3words - hash exactly 3, 2 or 1 word(s) */
-static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval)
+/* __jhash_nwords - hash exactly 3, 2 or 1 word(s) */
+static inline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
{
- a += JHASH_INITVAL;
- b += JHASH_INITVAL;
+ a += initval;
+ b += initval;
c += initval;
__jhash_final(a, b, c);
@@ -157,14 +157,19 @@ static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval)
return c;
}
+static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval)
+{
+ return __jhash_nwords(a, b, c, initval + JHASH_INITVAL + (3 << 2));
+}
+
static inline u32 jhash_2words(u32 a, u32 b, u32 initval)
{
- return jhash_3words(a, b, 0, initval);
+ return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2));
}
static inline u32 jhash_1word(u32 a, u32 initval)
{
- return jhash_3words(a, 0, 0, initval);
+ return __jhash_nwords(a, 0, 0, initval + JHASH_INITVAL + (1 << 2));
}
#endif /* _LINUX_JHASH_H */