runtime: clarify access to mheap_.busy

There are two accesses to mheap_.busy that are guarded by checks
against len(mheap_.free). This works because both lists are (and must
be) the same length, but it makes the code less clear. Change these to
use len(mheap_.busy) so the access more clearly parallels the check.

Fixes #18944.

Change-Id: I9bacbd3663988df351ed4396ae9018bc71018311
Reviewed-on: https://go-review.googlesource.com/36354
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>

diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index ef62eff6dadbbf09b1506314aa14e8cd7728558a..650a6d1a9cf8d7949beba2c32d70f66beec88988 100644 (file)
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -589,7 +589,7 @@ func (h *mheap) alloc_m(npage uintptr, sizeclass int32, large bool) *mspan {
                        memstats.heap_objects++
                        atomic.Xadd64(&memstats.heap_live, int64(npage<<_PageShift))
                        // Swept spans are at the end of lists.
-                       if s.npages < uintptr(len(h.free)) {
+                       if s.npages < uintptr(len(h.busy)) {
                                h.busy[s.npages].insertBack(s)
                        } else {
                                h.busylarge.insertBack(s)
@@ -941,7 +941,7 @@ func (h *mheap) freeList(npages uintptr) *mSpanList {
 }
 
 func (h *mheap) busyList(npages uintptr) *mSpanList {
-       if npages < uintptr(len(h.free)) {
+       if npages < uintptr(len(h.busy)) {
                return &h.busy[npages]
        }
        return &h.busylarge