diff options
Diffstat (limited to 'src/runtime/mbitmap.go')
| -rw-r--r-- | src/runtime/mbitmap.go | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/src/runtime/mbitmap.go b/src/runtime/mbitmap.go index 9600cddac8..55c0282403 100644 --- a/src/runtime/mbitmap.go +++ b/src/runtime/mbitmap.go @@ -243,6 +243,10 @@ func (s *mspan) nextFreeIndex() uintptr { } // isFree reports whether the index'th object in s is unallocated. +// +// The caller must ensure s.state is mSpanInUse, and there must have +// been no preemption points since ensuring this (which could allow a +// GC transition, which would allow the state to change). func (s *mspan) isFree(index uintptr) bool { if index < s.freeindex { return false @@ -361,12 +365,13 @@ func badPointer(s *mspan, p, refBase, refOff uintptr) { // in allocated spans. printlock() print("runtime: pointer ", hex(p)) - if s.state != mSpanInUse { + state := s.state.get() + if state != mSpanInUse { print(" to unallocated span") } else { print(" to unused region of span") } - print(" span.base()=", hex(s.base()), " span.limit=", hex(s.limit), " span.state=", s.state, "\n") + print(" span.base()=", hex(s.base()), " span.limit=", hex(s.limit), " span.state=", state, "\n") if refBase != 0 { print("runtime: found in object at *(", hex(refBase), "+", hex(refOff), ")\n") gcDumpObject("object", refBase, refOff) @@ -397,9 +402,12 @@ func findObject(p, refBase, refOff uintptr) (base uintptr, s *mspan, objIndex ui return } // If p is a bad pointer, it may not be in s's bounds. - if p < s.base() || p >= s.limit || s.state != mSpanInUse { + // + // Check s.state to synchronize with span initialization + // before checking other fields. See also spanOfHeap. + if state := s.state.get(); state != mSpanInUse || p < s.base() || p >= s.limit { // Pointers into stacks are also ok, the runtime manages these explicitly. - if s.state == mSpanManual { + if state == mSpanManual { return } // The following ensures that we are rigorous about what data @@ -620,7 +628,7 @@ func bulkBarrierPreWrite(dst, src, size uintptr) { } } return - } else if s.state != mSpanInUse || dst < s.base() || s.limit <= dst { + } else if s.state.get() != mSpanInUse || dst < s.base() || s.limit <= dst { // dst was heap memory at some point, but isn't now. // It can't be a global. It must be either our stack, // or in the case of direct channel sends, it could be |