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| author | Andrew G. Morgan <agm@google.com> | 2021-03-26 19:27:22 -0700 |
|---|---|---|
| committer | Michael Pratt <mpratt@google.com> | 2021-04-21 21:25:26 +0000 |
| commit | 7e97e4e8ccdba9677f31ab9380802cd7613f62c5 (patch) | |
| tree | 74a0797fa08596e554f1f5f6070fb95ea961aba3 /src/runtime/runtime2.go | |
| parent | 54af9fd9e69d5cc33b16b9a32d9f7dc71eef0d18 (diff) | |
| download | go-7e97e4e8ccdba9677f31ab9380802cd7613f62c5.tar.gz go-7e97e4e8ccdba9677f31ab9380802cd7613f62c5.zip | |
syscall: syscall.AllThreadsSyscall signal handling fixes
The runtime support for syscall.AllThreadsSyscall() functions had
some corner case deadlock issues when signal handling was in use.
This was observed in at least 3 build test failures on ppc64 and
amd64 architecture CGO_ENABLED=0 builds over the last few months.
The fixes involve more controlled handling of signals while the
AllThreads mechanism is being executed. Further details are
discussed in bug #44193.
The all-threads syscall support is new in go1.16, so earlier
releases are not affected by this bug.
Fixes #44193
Change-Id: I01ba8508a6e1bb2d872751f50da86dd07911a41d
Reviewed-on: https://go-review.googlesource.com/c/go/+/305149
Reviewed-by: Michael Pratt <mpratt@google.com>
Trust: Michael Pratt <mpratt@google.com>
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Diffstat (limited to 'src/runtime/runtime2.go')
| -rw-r--r-- | src/runtime/runtime2.go | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index 387841e60b..f84cb51bad 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -554,10 +554,13 @@ type m struct { syscalltick uint32 freelink *m // on sched.freem - // mFixup is used to synchronize OS related m state (credentials etc) - // use mutex to access. + // mFixup is used to synchronize OS related m state + // (credentials etc) use mutex to access. To avoid deadlocks + // an atomic.Load() of used being zero in mDoFixupFn() + // guarantees fn is nil. mFixup struct { lock mutex + used uint32 fn func(bool) bool } |