[go] runtime: fix lock rank for work.spanSPMCs.lock

[Michael Knyszek (Gerrit)]

Michael Knyszek submitted the change

Change information

Commit message:

runtime: fix lock rank for work.spanSPMCs.lock

Currently this lock is treated like a leaf lock, but it's not one. It
can acquire the globalAlloc lock via fixalloc and persistentalloc.

This means we need to figure out where it can be acquired. In general,
it can be acquired by any write barrier, which is already incredibly
broad. AFAICT, it can't be acquired directly otherwise, except when
destroying a spanSPMC during procresize, in which case we'll be holding
sched.lock.

Fixes #75916.

Change-Id: I2da1f5b82c750bf4e8d6a8a562046b9a17fd44be

Reviewed-on: https://go-review.googlesource.com/c/go/+/717500

Reviewed-by: Michael Pratt <mpr...@google.com>

LUCI-TryBot-Result: Go LUCI <golang...@luci-project-accounts.iam.gserviceaccount.com>

Files:

• M src/runtime/lockrank.go
• M src/runtime/mgc.go
• M src/runtime/mklockrank.go

Change size: S

Delta: 3 files changed, 10 insertions(+), 3 deletions(-)

Branch: refs/heads/master

Submit Requirements:

• Code-Review: +2 by Michael Pratt
• TryBots-Pass: LUCI-TryBot-Result+1 by Go LUCI

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Gerrit

Gerrit-MessageType: merged

Gerrit-Project: go

Gerrit-Branch: master

Gerrit-Change-Id: I2da1f5b82c750bf4e8d6a8a562046b9a17fd44be

Gerrit-Change-Number: 717500

Gerrit-PatchSet: 2

Gerrit-Owner: Michael Knyszek <mkny...@google.com>

Gerrit-Reviewer: Go LUCI <golang...@luci-project-accounts.iam.gserviceaccount.com>

Gerrit-Reviewer: Michael Knyszek <mkny...@google.com>

Gerrit-Reviewer: Michael Pratt <mpr...@google.com>