diff options
Diffstat (limited to 'src/runtime/proc1.go')
| -rw-r--r-- | src/runtime/proc1.go | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/runtime/proc1.go b/src/runtime/proc1.go index 81b211d0d..aeded0e77 100644 --- a/src/runtime/proc1.go +++ b/src/runtime/proc1.go @@ -371,6 +371,11 @@ func casgstatus(gp *g, oldval, newval uint32) { // loop if gp->atomicstatus is in a scan state giving // GC time to finish and change the state to oldval. for !cas(&gp.atomicstatus, oldval, newval) { + if oldval == _Gwaiting && gp.atomicstatus == _Grunnable { + systemstack(func() { + gothrow("casgstatus: waiting for Gwaiting but is Grunnable") + }) + } // Help GC if needed. if gp.preemptscan && !gp.gcworkdone && (oldval == _Grunning || oldval == _Gsyscall) { gp.preemptscan = false @@ -381,6 +386,24 @@ func casgstatus(gp *g, oldval, newval uint32) { } } +// casgstatus(gp, oldstatus, Gcopystack), assuming oldstatus is Gwaiting or Grunnable. +// Returns old status. Cannot call casgstatus directly, because we are racing with an +// async wakeup that might come in from netpoll. If we see Gwaiting from the readgstatus, +// it might have become Grunnable by the time we get to the cas. If we called casgstatus, +// it would loop waiting for the status to go back to Gwaiting, which it never will. +//go:nosplit +func casgcopystack(gp *g) uint32 { + for { + oldstatus := readgstatus(gp) &^ _Gscan + if oldstatus != _Gwaiting && oldstatus != _Grunnable { + gothrow("copystack: bad status, not Gwaiting or Grunnable") + } + if cas(&gp.atomicstatus, oldstatus, _Gcopystack) { + return oldstatus + } + } +} + // stopg ensures that gp is stopped at a GC safe point where its stack can be scanned // or in the context of a moving collector the pointers can be flipped from pointing // to old object to pointing to new objects. |