wait: Fix __wait_event_hrtimeout for RT/DL tasks

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 <bgoncalv@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20220627095051.42470-1-juri.lelli@redhat.com

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 851e07da2583fb231e647db74fbc6ce07cb6e2f0..58cfbf81447cc10373cf8a90baf84a5ce2592098 100644 (file)
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -544,10 +544,11 @@ 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) {                                                \