Commit 37250097 authored Aug 09, 2007 by Rusty Russell Committed by Linus Torvalds Aug 09, 2007

Fix non-TSC guest clocksource lockup



lguest uses a host-supplied wallclock-based clocksource when the TSC
is not reliable.  As this is already in nanoseconds, I naively used a
multiplier of 1 and a shift of 0.

But update_wall_time() in its infinite wisdom decides to adjust the
clock a little (where does it think it's getting a more accurate time
from?)

It will happily tweak the multiplier... to 0, then -1.

So the "fix" is to use a shift of 22 like everyone else, and a
multiplier of 1 << 22.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 88ffc350

drivers/lguest/lguest.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -687,7 +687,8 @@ static struct clocksource lguest_clock = {
		.rating = 400,
		.read = lguest_clock_read,
		.mask = CLOCKSOURCE_MASK(64),
		.mult = 1,
		.mult = 1 << 22,
		.shift = 22,
		};

		/* The "scheduler clock" is just our real clock, adjusted to start at zero */
		@@ -770,7 +771,6 @@ static void lguest_time_init(void)
		* way, the "rating" is initialized so high that it's always chosen
		* over any other clocksource. */
		if (lguest_data.tsc_khz) {
		lguest_clock.shift = 22;
		lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
		lguest_clock.shift);
		lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS;

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