runtime: fix plan9 HeapSys accounting

LGTM=0intro
R=0intro
CC=golang-codereviews
https://golang.org/cl/131190043

diff --git a/src/pkg/runtime/mem_plan9.c b/src/pkg/runtime/mem_plan9.c
index bbf04c7eda1d1d31a6762c9122153ca113d8453c..ea35a1709cea77933a94334807cd82e92fde1345 100644 (file)
--- a/src/pkg/runtime/mem_plan9.c
+++ b/src/pkg/runtime/mem_plan9.c
@@ -17,8 +17,8 @@ enum
        Round = PAGESIZE-1
 };
 
-void*
-runtime·SysAlloc(uintptr nbytes, uint64 *stat)
+static void*
+brk(uintptr nbytes)
 {
        uintptr bl;
 
@@ -31,8 +31,19 @@ runtime·SysAlloc(uintptr nbytes, uint64 *stat)
        }
        bloc = (byte*)bl + nbytes;
        runtime·unlock(&memlock);
-       runtime·xadd64(stat, nbytes);
        return (void*)bl;
+       
+}
+
+void*
+runtime·SysAlloc(uintptr nbytes, uint64 *stat)
+{
+       void *p;
+
+       p = brk(nbytes);
+       if(p != nil)
+               runtime·xadd64(stat, nbytes);
+       return p;
 }
 
 void
@@ -64,7 +75,10 @@ runtime·SysUsed(void *v, uintptr nbytes)
 void
 runtime·SysMap(void *v, uintptr nbytes, bool reserved, uint64 *stat)
 {
-       USED(v, nbytes, reserved, stat);
+       // SysReserve has already allocated all heap memory,
+       // but has not adjusted stats.
+       USED(v, reserved);
+       runtime·xadd64(stat, nbytes);
 }
 
 void
@@ -78,5 +92,5 @@ runtime·SysReserve(void *v, uintptr nbytes, bool *reserved)
 {
        USED(v);
        *reserved = true;
-       return runtime·SysAlloc(nbytes, &mstats.heap_sys);
+       return brk(nbytes);
 }