| commit | e8be350d78f3fd21b0fab4cc6909c03fe21f1640 | [log] [tgz] |
|---|---|---|
| author | Michael Anthony Knyszek <mknyszek@google.com> | Wed Mar 25 16:41:20 2020 +0000 |
| committer | Michael Knyszek <mknyszek@google.com> | Wed Mar 25 20:14:03 2020 +0000 |
| tree | c47d4038ac82334157b2c40767dbc6da3cb2e29e | |
| parent | b878d8db66faf9f8d9b2ff394123cdde21d93f8d [diff] |
runtime: prevent preemption while timer is in timerModifying Currently if a goroutine is preempted while owning a timer in the timerModifying state, it could self-deadlock. When the goroutine is preempted and calls into the scheduler, it could call checkTimers. If checkTimers encounters the timerModifying timer and calls runtimer on it, then runtimer will spin, waiting for that timer to leave the timerModifying state, which it never will. So far we got lucky that for the most part that there were no preemption points while timerModifying is happening, however CL 221077 seems to have introduced one, leading to sporadic self-deadlocks. This change disables preemption explicitly while a goroutines holds a timer in timerModifying. Since only checkTimers (and thus runtimer) is called from the scheduler, this is sufficient to prevent preemption-based self-deadlocks. Fixes #38070. Updates #37894. Change-Id: Idbfac310889c92773023733ff7e2ff87e9896f0c Reviewed-on: https://go-review.googlesource.com/c/go/+/225497 Run-TryBot: Michael Knyszek <mknyszek@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
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