From bd80dd86f9bfc6c86ac7dfda912b6706953c4b59 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Mon, 27 Jun 2022 11:50:51 +0200 Subject: [PATCH] wait: Fix __wait_event_hrtimeout for RT/DL tasks [ Upstream commit cceeeb6a6d02e7b9a74ddd27a3225013b34174aa ] Changes to hrtimer mode (potentially made by __hrtimer_init_sleeper on PREEMPT_RT) are not visible to hrtimer_start_range_ns, thus not accounted for by hrtimer_start_expires call paths. In particular, __wait_event_hrtimeout suffers from this problem as we have, for example: fs/aio.c::read_events wait_event_interruptible_hrtimeout __wait_event_hrtimeout hrtimer_init_sleeper_on_stack <- this might "mode |= HRTIMER_MODE_HARD" on RT if task runs at RT/DL priority hrtimer_start_range_ns WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard) fires since the latter doesn't see the change of mode done by init_sleeper Fix it by making __wait_event_hrtimeout call hrtimer_sleeper_start_expires, which is aware of the special RT/DL case, instead of hrtimer_start_range_ns. Reported-by: Bruno Goncalves Signed-off-by: Juri Lelli Signed-off-by: Thomas Gleixner Reviewed-by: Daniel Bristot de Oliveira Reviewed-by: Valentin Schneider Link: https://lore.kernel.org/r/20220627095051.42470-1-juri.lelli@redhat.com Signed-off-by: Sasha Levin --- include/linux/wait.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/include/linux/wait.h b/include/linux/wait.h index 5903b1d17c92..7d04c1b588c7 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -529,10 +529,11 @@ do { \ \ hrtimer_init_sleeper_on_stack(&__t, CLOCK_MONOTONIC, \ HRTIMER_MODE_REL); \ - if ((timeout) != KTIME_MAX) \ - hrtimer_start_range_ns(&__t.timer, timeout, \ - current->timer_slack_ns, \ - HRTIMER_MODE_REL); \ + if ((timeout) != KTIME_MAX) { \ + hrtimer_set_expires_range_ns(&__t.timer, timeout, \ + current->timer_slack_ns); \ + hrtimer_sleeper_start_expires(&__t, HRTIMER_MODE_REL); \ + } \ \ __ret = ___wait_event(wq_head, condition, state, 0, 0, \ if (!__t.task) { \