diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/mgcmark.go | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/runtime/mgcmark.go b/src/runtime/mgcmark.go index 30a73178ac..71092cb19d 100644 --- a/src/runtime/mgcmark.go +++ b/src/runtime/mgcmark.go @@ -521,6 +521,10 @@ func gcAssistAlloc1(gp *g, scanWork int64) { throw("nwait > work.nprocs") } + // gcDrainN requires the caller to be preemptible. + casgstatus(gp, _Grunning, _Gwaiting) + gp.waitreason = "GC assist marking" + // drain own cached work first in the hopes that it // will be more cache friendly. gcw := &getg().m.p.ptr().gcw @@ -531,6 +535,8 @@ func gcAssistAlloc1(gp *g, scanWork int64) { gcw.dispose() } + casgstatus(gp, _Gwaiting, _Grunning) + // Record that we did this much scan work. // // Back out the number of bytes of assist credit that @@ -1083,7 +1089,13 @@ func gcDrain(gcw *gcWork, flags gcDrainFlags) { // buffer. Otherwise, it will perform at least n units of work, but // may perform more because scanning is always done in whole object // increments. It returns the amount of scan work performed. +// +// The caller goroutine must be in a preemptible state (e.g., +// _Gwaiting) to prevent deadlocks during stack scanning. As a +// consequence, this must be called on the system stack. +// //go:nowritebarrier +//go:systemstack func gcDrainN(gcw *gcWork, scanWork int64) int64 { if !writeBarrier.needed { throw("gcDrainN phase incorrect") @@ -1111,6 +1123,18 @@ func gcDrainN(gcw *gcWork, scanWork int64) int64 { } if b == 0 { + // Try to do a root job. + // + // TODO: Assists should get credit for this + // work. + if work.markrootNext < work.markrootJobs { + job := atomic.Xadd(&work.markrootNext, +1) - 1 + if job < work.markrootJobs { + markroot(gcw, job) + continue + } + } + // No heap or root jobs. break } scanobject(b, gcw) |