runtime: deconflict gscan and mutex profiler

Measuring contention on runtime-internal mutex values involves some
unlock2 calls acquiring the leaf-like profInsert mutex. It's not safe to
do that when the M holds other mutex locks, and also not safe when the M
is running a G with the Gscan bit set. CL 571056 codified the
interaction between gscan and profInsert, but CL 779160 inadvertently
broke that. Put it back.

For #58277

Change-Id: I68d980a05481664f81e6e6f0e59f74b491b8c6df
Reviewed-on: https://go-review.googlesource.com/c/go/+/788560
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Florian Lehner <lehner.florian86@gmail.com>
Auto-Submit: Rhys Hiltner <rhys.hiltner@gmail.com>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
2 files changed
tree: b29b7e6c10fd75d49d35a1b7d4b1ce4813de0e43
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. codereview.cfg
  11. CONTRIBUTING.md
  12. go.env
  13. LICENSE
  14. PATENTS
  15. README.md
  16. SECURITY.md
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