From: Jason A. Donenfeld Jason@zx2c4.com
[ Upstream commit 151c8e499f4705010780189377f85b57400ccbf5 ]
Using msleep() is problematic because it's compared against ratelimiter.c's ktime_get_coarse_boottime_ns(), which means on systems with slow jiffies (such as UML's forced HZ=100), the result is inaccurate. So switch to using schedule_hrtimeout().
However, hrtimer gives us access only to the traditional posix timers, and none of the _COARSE variants. So now, rather than being too imprecise like jiffies, it's too precise.
One solution would be to give it a large "range" value, but this will still fire early on a loaded system. A better solution is to align the timeout to the actual coarse timer, and then round up to the nearest tick, plus change.
So add the timeout to the current coarse time, and then schedule_hrtimer() until the absolute computed time.
This should hopefully reduce flakes in CI as well. Note that we keep the retry loop in case the entire function is running behind, because the test could still be scheduled out, by either the kernel or by the hypervisor's kernel, in which case restarting the test and hoping to not be scheduled out still helps.
Fixes: e7096c131e51 ("net: WireGuard secure network tunnel") Suggested-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireguard/selftest/ratelimiter.c | 25 +++++++++++--------- kernel/time/hrtimer.c | 1 + 2 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/drivers/net/wireguard/selftest/ratelimiter.c b/drivers/net/wireguard/selftest/ratelimiter.c index 007cd4457c5f..ba87d294604f 100644 --- a/drivers/net/wireguard/selftest/ratelimiter.c +++ b/drivers/net/wireguard/selftest/ratelimiter.c @@ -6,28 +6,29 @@ #ifdef DEBUG
#include <linux/jiffies.h> +#include <linux/hrtimer.h>
static const struct { bool result; - unsigned int msec_to_sleep_before; + u64 nsec_to_sleep_before; } expected_results[] __initconst = { [0 ... PACKETS_BURSTABLE - 1] = { true, 0 }, [PACKETS_BURSTABLE] = { false, 0 }, - [PACKETS_BURSTABLE + 1] = { true, MSEC_PER_SEC / PACKETS_PER_SECOND }, + [PACKETS_BURSTABLE + 1] = { true, NSEC_PER_SEC / PACKETS_PER_SECOND }, [PACKETS_BURSTABLE + 2] = { false, 0 }, - [PACKETS_BURSTABLE + 3] = { true, (MSEC_PER_SEC / PACKETS_PER_SECOND) * 2 }, + [PACKETS_BURSTABLE + 3] = { true, (NSEC_PER_SEC / PACKETS_PER_SECOND) * 2 }, [PACKETS_BURSTABLE + 4] = { true, 0 }, [PACKETS_BURSTABLE + 5] = { false, 0 } };
static __init unsigned int maximum_jiffies_at_index(int index) { - unsigned int total_msecs = 2 * MSEC_PER_SEC / PACKETS_PER_SECOND / 3; + u64 total_nsecs = 2 * NSEC_PER_SEC / PACKETS_PER_SECOND / 3; int i;
for (i = 0; i <= index; ++i) - total_msecs += expected_results[i].msec_to_sleep_before; - return msecs_to_jiffies(total_msecs); + total_nsecs += expected_results[i].nsec_to_sleep_before; + return nsecs_to_jiffies(total_nsecs); }
static __init int timings_test(struct sk_buff *skb4, struct iphdr *hdr4, @@ -42,8 +43,12 @@ static __init int timings_test(struct sk_buff *skb4, struct iphdr *hdr4, loop_start_time = jiffies;
for (i = 0; i < ARRAY_SIZE(expected_results); ++i) { - if (expected_results[i].msec_to_sleep_before) - msleep(expected_results[i].msec_to_sleep_before); + if (expected_results[i].nsec_to_sleep_before) { + ktime_t timeout = ktime_add(ktime_add_ns(ktime_get_coarse_boottime(), TICK_NSEC * 4 / 3), + ns_to_ktime(expected_results[i].nsec_to_sleep_before)); + set_current_state(TASK_UNINTERRUPTIBLE); + schedule_hrtimeout_range_clock(&timeout, 0, HRTIMER_MODE_ABS, CLOCK_BOOTTIME); + }
if (time_is_before_jiffies(loop_start_time + maximum_jiffies_at_index(i))) @@ -127,7 +132,7 @@ bool __init wg_ratelimiter_selftest(void) if (IS_ENABLED(CONFIG_KASAN) || IS_ENABLED(CONFIG_UBSAN)) return true;
- BUILD_BUG_ON(MSEC_PER_SEC % PACKETS_PER_SECOND != 0); + BUILD_BUG_ON(NSEC_PER_SEC % PACKETS_PER_SECOND != 0);
if (wg_ratelimiter_init()) goto out; @@ -176,7 +181,6 @@ bool __init wg_ratelimiter_selftest(void) test += test_count; goto err; } - msleep(500); continue; } else if (ret < 0) { test += test_count; @@ -195,7 +199,6 @@ bool __init wg_ratelimiter_selftest(void) test += test_count; goto err; } - msleep(50); continue; } test += test_count; diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 4ef90718c114..544ce87ba38a 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -2209,6 +2209,7 @@ schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
return !t.task ? 0 : -EINTR; } +EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
/** * schedule_hrtimeout_range - sleep until timeout