From 5b0ce94c07524f910278de1d90e31c5bc0805bbd Mon Sep 17 00:00:00 2001 From: Cuong Manh Le Date: Wed, 17 Aug 2022 14:13:06 +0700 Subject: [PATCH] runtime: convert g.parkingOnChan to atomic type Updates #53821 Change-Id: I54de39b984984fb3c160aba5afacb90131fd47c4 Reviewed-on: https://go-review.googlesource.com/c/go/+/424394 TryBot-Result: Gopher Robot Reviewed-by: Keith Randall Run-TryBot: Cuong Manh Le Reviewed-by: Michael Pratt Auto-Submit: Cuong Manh Le --- src/runtime/chan.go | 6 +++--- src/runtime/runtime2.go | 4 ++-- src/runtime/select.go | 5 ++--- src/runtime/stack.go | 4 ++-- 4 files changed, 9 insertions(+), 10 deletions(-) diff --git a/src/runtime/chan.go b/src/runtime/chan.go index ca516ad9e8..853a300ab5 100644 --- a/src/runtime/chan.go +++ b/src/runtime/chan.go @@ -255,7 +255,7 @@ func chansend(c *hchan, ep unsafe.Pointer, block bool, callerpc uintptr) bool { // to park on a channel. The window between when this G's status // changes and when we set gp.activeStackChans is not safe for // stack shrinking. - atomic.Store8(&gp.parkingOnChan, 1) + gp.parkingOnChan.Store(true) gopark(chanparkcommit, unsafe.Pointer(&c.lock), waitReasonChanSend, traceEvGoBlockSend, 2) // Ensure the value being sent is kept alive until the // receiver copies it out. The sudog has a pointer to the @@ -579,7 +579,7 @@ func chanrecv(c *hchan, ep unsafe.Pointer, block bool) (selected, received bool) // to park on a channel. The window between when this G's status // changes and when we set gp.activeStackChans is not safe for // stack shrinking. - atomic.Store8(&gp.parkingOnChan, 1) + gp.parkingOnChan.Store(true) gopark(chanparkcommit, unsafe.Pointer(&c.lock), waitReasonChanReceive, traceEvGoBlockRecv, 2) // someone woke us up @@ -664,7 +664,7 @@ func chanparkcommit(gp *g, chanLock unsafe.Pointer) bool { // Mark that it's safe for stack shrinking to occur now, // because any thread acquiring this G's stack for shrinking // is guaranteed to observe activeStackChans after this store. - atomic.Store8(&gp.parkingOnChan, 0) + gp.parkingOnChan.Store(false) // Make sure we unlock after setting activeStackChans and // unsetting parkingOnChan. The moment we unlock chanLock // we risk gp getting readied by a channel operation and diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index 32ad34ccdf..2fbb1d1744 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -461,8 +461,8 @@ type g struct { activeStackChans bool // parkingOnChan indicates that the goroutine is about to // park on a chansend or chanrecv. Used to signal an unsafe point - // for stack shrinking. It's a boolean value, but is updated atomically. - parkingOnChan uint8 + // for stack shrinking. + parkingOnChan atomic.Bool raceignore int8 // ignore race detection events sysblocktraced bool // StartTrace has emitted EvGoInSyscall about this goroutine diff --git a/src/runtime/select.go b/src/runtime/select.go index e18b2f14c0..2dd6333fa7 100644 --- a/src/runtime/select.go +++ b/src/runtime/select.go @@ -8,7 +8,6 @@ package runtime import ( "internal/abi" - "runtime/internal/atomic" "unsafe" ) @@ -70,7 +69,7 @@ func selparkcommit(gp *g, _ unsafe.Pointer) bool { // Mark that it's safe for stack shrinking to occur now, // because any thread acquiring this G's stack for shrinking // is guaranteed to observe activeStackChans after this store. - atomic.Store8(&gp.parkingOnChan, 0) + gp.parkingOnChan.Store(false) // Make sure we unlock after setting activeStackChans and // unsetting parkingOnChan. The moment we unlock any of the // channel locks we risk gp getting readied by a channel operation @@ -324,7 +323,7 @@ func selectgo(cas0 *scase, order0 *uint16, pc0 *uintptr, nsends, nrecvs int, blo // to park on a channel. The window between when this G's status // changes and when we set gp.activeStackChans is not safe for // stack shrinking. - atomic.Store8(&gp.parkingOnChan, 1) + gp.parkingOnChan.Store(true) gopark(selparkcommit, nil, waitReasonSelect, traceEvGoBlockSelect, 1) gp.activeStackChans = false diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 2a7f0bd1c3..0bfa9320e0 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -886,7 +886,7 @@ func copystack(gp *g, newsize uintptr) { // Adjust sudogs, synchronizing with channel ops if necessary. ncopy := used if !gp.activeStackChans { - if newsize < old.hi-old.lo && atomic.Load8(&gp.parkingOnChan) != 0 { + if newsize < old.hi-old.lo && gp.parkingOnChan.Load() { // It's not safe for someone to shrink this stack while we're actively // parking on a channel, but it is safe to grow since we do that // ourselves and explicitly don't want to synchronize with channels @@ -1150,7 +1150,7 @@ func isShrinkStackSafe(gp *g) bool { // We also can't *shrink* the stack in the window between the // goroutine calling gopark to park on a channel and // gp.activeStackChans being set. - return gp.syscallsp == 0 && !gp.asyncSafePoint && atomic.Load8(&gp.parkingOnChan) == 0 + return gp.syscallsp == 0 && !gp.asyncSafePoint && !gp.parkingOnChan.Load() } // Maybe shrink the stack being used by gp. -- 2.50.0