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runtime: fix stack-move sensitivity in some tests

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There are a few tests of the scheduler run queue API that allocate a
local []g and test using those G's. However, the run queue API
frequently converts between *g and guintptr, which is safe for "real"
Gs because they're heap-allocated and hence don't move, but if these
tests get a stack movement while holding one of these local *g's as a
guintptr, it won't get updated and the test will fail.

Updates #48297.

Change-Id: Ifd424147ce1a1b53732ff0cf55a81df1a9beeb3b
Reviewed-on: https://go-review.googlesource.com/c/go/+/402157
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Austin Clements 2022-04-25 12:25:59 -04:00
parent 12763d141d
commit 8619d3b2ec
1 changed files with 6 additions and 2 deletions
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8
src/runtime/export_test.go
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@ -85,6 +85,7 @@ func GCMask(x any) (ret []byte) {
func RunSchedLocalQueueTest() {
_p_ := new(p)
gs := make([]g, len(_p_.runq))
escape(gs) // Ensure gs doesn't move, since we use guintptrs
for i := 0; i < len(_p_.runq); i++ {
if g, _ := runqget(_p_); g != nil {
throw("runq is not empty initially")
@ -108,6 +109,7 @@ func RunSchedLocalQueueStealTest() {
p1 := new(p)
p2 := new(p)
gs := make([]g, len(p1.runq))
escape(gs) // Ensure gs doesn't move, since we use guintptrs
for i := 0; i < len(p1.runq); i++ {
for j := 0; j < i; j++ {
gs[j].sig = 0
@ -155,6 +157,7 @@ func RunSchedLocalQueueEmptyTest(iters int) {
done := make(chan bool, 1)
p := new(p)
gs := make([]g, 2)
escape(gs) // Ensure gs doesn't move, since we use guintptrs
ready := new(uint32)
for i := 0; i < iters; i++ {
*ready = 0
@ -1257,7 +1260,7 @@ func NewGCController(gcPercent int) *GCController {
// do 64-bit atomics on it, and if it gets stack-allocated
// on a 32-bit architecture, it may get allocated unaligned
// space.
g := escape(new(GCController)).(*GCController)
g := escape(new(GCController))
g.gcControllerState.test = true // Mark it as a test copy.
g.init(int32(gcPercent))
return g
@ -1318,7 +1321,8 @@ func (c *GCController) EndCycle(bytesMarked uint64, assistTime, elapsed int64, g
var escapeSink any
//go:noinline
func escape(x any) any {
//go:norace
func escape[T any](x T) T {
escapeSink = x
escapeSink = nil
return x