Author: Frank Sorenson <[email protected]>
Date: 2016-06-27 13:55:48 -0500
sunrpc: Fix bit count when setting hashtable size to power-of-two
The hashtable size is incorrectly calculated as the next higher
power-of-two when being set to a power-of-two. fls() returns the
bit number of the most significant set bit, with the least
significant bit being numbered '1'. For a power-of-two, fls()
will return a bit number which is one higher than the number of bits
required, leading to a hashtable which is twice the requested size.
In addition, the value of (1 << nbits) will always be at least num,
so the test will never be true.
Fix the hash table size calculation to correctly set hashtable
size, and eliminate the unnecessary check.
Signed-off-by: Frank Sorenson <[email protected]>
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 040ff62..9d7056f 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -51,9 +51,7 @@ static int param_set_hashtbl_sz(const char *val, const struct kernel_param *kp)
ret = kstrtoul(val, 0, &num);
if (ret == -EINVAL)
goto out_inval;
- nbits = fls(num);
- if (num > (1U << nbits))
- nbits++;
+ nbits = fls(num - 1);
if (nbits > MAX_HASHTABLE_BITS || nbits < 2)
goto out_inval;
*(unsigned int *)kp->arg = nbits;