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runtime: use a distinct pattern to mark free blocks in need of zeroing

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R=golang-dev, dvyukov, khr, cshapiro
CC=golang-dev
https://golang.org/cl/8392043
This commit is contained in:
Carl Shapiro 2013-04-04 14:18:52 -07:00
parent 13d6f8f7f3
commit c80f5b9bf7
2 changed files with 4 additions and 4 deletions
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4
src/pkg/runtime/malloc.goc
View file

@ -160,7 +160,7 @@ runtime·free(void *v)
if(sizeclass == 0) {
// Large object.
size = s->npages<<PageShift;
*(uintptr*)(s->start<<PageShift) = 1; // mark as "needs to be zeroed"
*(uintptr*)(s->start<<PageShift) = (uintptr)0xfeedfeedfeedfeedll; // mark as "needs to be zeroed"
// Must mark v freed before calling unmarkspan and MHeap_Free:
// they might coalesce v into other spans and change the bitmap further.
runtime·markfreed(v, size);
@ -170,7 +170,7 @@ runtime·free(void *v)
// Small object.
size = runtime·class_to_size[sizeclass];
if(size > sizeof(uintptr))
((uintptr*)v)[1] = 1; // mark as "needs to be zeroed"
((uintptr*)v)[1] = (uintptr)0xfeedfeedfeedfeedll; // mark as "needs to be zeroed"
// Must mark v freed before calling MCache_Free:
// it might coalesce v and other blocks into a bigger span
// and change the bitmap further.

4
src/pkg/runtime/mgc0.c
View file

@ -1607,7 +1607,7 @@ sweepspan(ParFor *desc, uint32 idx)
if(cl == 0) {
// Free large span.
runtime·unmarkspan(p, 1<<PageShift);
*(uintptr*)p = 1; // needs zeroing
*(uintptr*)p = (uintptr)0xdeaddeaddeaddeadll; // needs zeroing
runtime·MHeap_Free(runtime·mheap, s, 1);
c->local_alloc -= size;
c->local_nfree++;
@ -1622,7 +1622,7 @@ sweepspan(ParFor *desc, uint32 idx)
break;
}
if(size > sizeof(uintptr))
((uintptr*)p)[1] = 1; // mark as "needs to be zeroed"
((uintptr*)p)[1] = (uintptr)0xdeaddeaddeaddeadll; // mark as "needs to be zeroed"
end->next = (MLink*)p;
end = (MLink*)p;