commit cedae7f75bb8cf3cd9de61bf8990f23c628ade16
author Kevin Lindkvist <lindkvist@google.com> Fri Oct 04 01:45:02 2024 +0000
committer CQ Bot <fuchsia-internal-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Oct 04 01:45:02 2024 +0000
tree abc2259f5a776ce86d52563638c821a69bc54c0f
parent a8cb1d66f1a4436ed80201dfc5642a7d85248842

[starnix] Only remove the timer when deadline hasn't changed

Previously we would always remove the "same timer" from the heap, even
if the deadline for it had changed. This introduced a race condition
where:

  1. An interval timer was scheduled with deadline A.
  2. The "local" timer triggered, the outstanding hrtimer call was
     cancelled, and the timer's deadline was updated.
  3. The hrtimer actually had time to trigger, so the callback was
     called. This callback removed the timer from the timer heap, since
     it relies on the interval timer logic to reschedule the timer
     appropriately.

However, the timer had already been re-added (with a new deadline) to
the heap, so removing it caused us to remove the next instance of the
timer.

Longer term we likely need to come up with a different structure for
managing the timer <-> hrtimer relationship. We could also introduce an
API that is easier to use for us to schedule Fuchsia wake alarms in a
hardware-agnostic way. That component could then be responsible for
managing the actual hrtimers.

Test: This will be tested by the sysfs suspend tests in a future change.

Fixed: 371006392
Change-Id: Ieba9af4275941e186b0bc74a0f934ee40aba3ecb
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1130458
Reviewed-by: Guocheng Wei <guochengwei@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
Fuchsia-Auto-Submit: Kevin Lindkvist <lindkvist@google.com>