random: cap jitter samples per bit to factor of HZ
Currently the jitter mechanism will require two timer ticks per iteration, and it requires N iterations per bit. This N is determined with a small measurement, and if it's too big, it won't waste time with jitter entropy because it'd take too long or not have sufficient entropy anyway. With the current max N of 32, there are large timeouts on systems with a small CONFIG_HZ. Rather than set that maximum to 32, instead choose a factor of CONFIG_HZ. In this case, 1/30 seems to yield sane values for different configurations of CONFIG_HZ. Reported-by:Vladimir Murzin <vladimir.murzin@arm.com> Fixes: 78c768e6 ("random: vary jitter iterations based on cycle counter speed") Signed-off-by:
Jason A. Donenfeld <Jason@zx2c4.com> Tested-by:
Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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51a6fa07
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