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runtime: remove atomic CAS loop from marknogc

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Spans are now private to threads, and the loop
is removed from all other functions.
Remove it from marknogc for consistency.

LGTM=khr, rsc
R=golang-codereviews, bradfitz, khr
CC=golang-codereviews, khr, rsc
https://golang.org/cl/72520043
This commit is contained in:
Dmitriy Vyukov 2014-03-11 17:35:49 +04:00
parent 38f6c3f59d
commit 3877f1d9c8
1 changed files with 2 additions and 16 deletions
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18
src/pkg/runtime/mgc0.c
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@ -2614,26 +2614,12 @@ runfinq(void)
void
runtime·marknogc(void *v)
{
uintptr *b, obits, bits, off, shift;
uintptr *b, off, shift;
off = (uintptr*)v - (uintptr*)runtime·mheap.arena_start; // word offset
b = (uintptr*)runtime·mheap.arena_start - off/wordsPerBitmapWord - 1;
shift = off % wordsPerBitmapWord;
for(;;) {
obits = *b;
if((obits>>shift & bitMask) != bitAllocated)
runtime·throw("bad initial state for marknogc");
bits = (obits & ~(bitAllocated<<shift)) | bitBlockBoundary<<shift;
if(runtime·gomaxprocs == 1) {
*b = bits;
break;
} else {
// more than one goroutine is potentially running: use atomic op
if(runtime·casp((void**)b, (void*)obits, (void*)bits))
break;
}
}
*b = (*b & ~(bitAllocated<<shift)) | bitBlockBoundary<<shift;
}
void