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runtime: change Note from union to struct

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Unions can break precise GC.
Update #5193.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8362046
This commit is contained in:
Dmitriy Vyukov 2013-04-06 20:09:02 -07:00
parent d617454379
commit 58030c541b
3 changed files with 22 additions and 20 deletions
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14
src/pkg/runtime/lock_futex.c
View File

@ -111,9 +111,9 @@ runtime·noteclear(Note *n)
void
runtime·notewakeup(Note *n)
{
if(runtime·xchg(&n->key, 1))
if(runtime·xchg((uint32*)&n->key, 1))
runtime·throw("notewakeup - double wakeup");
runtime·futexwakeup(&n->key, 1);
runtime·futexwakeup((uint32*)&n->key, 1);
}
void
@ -121,8 +121,8 @@ runtime·notesleep(Note *n)
{
if(m->profilehz > 0)
runtime·setprof(false);
while(runtime·atomicload(&n->key) == 0)
runtime·futexsleep(&n->key, 0, -1);
while(runtime·atomicload((uint32*)&n->key) == 0)
runtime·futexsleep((uint32*)&n->key, 0, -1);
if(m->profilehz > 0)
runtime·setprof(true);
}
@ -137,15 +137,15 @@ runtime·notetsleep(Note *n, int64 ns)
return;
}
if(runtime·atomicload(&n->key) != 0)
if(runtime·atomicload((uint32*)&n->key) != 0)
return;
if(m->profilehz > 0)
runtime·setprof(false);
deadline = runtime·nanotime() + ns;
for(;;) {
runtime·futexsleep(&n->key, 0, ns);
if(runtime·atomicload(&n->key) != 0)
runtime·futexsleep((uint32*)&n->key, 0, ns);
if(runtime·atomicload((uint32*)&n->key) != 0)
break;
now = runtime·nanotime();
if(now >= deadline)

18
src/pkg/runtime/lock_sema.c
View File

@ -118,7 +118,7 @@ runtime·unlock(Lock *l)
void
runtime·noteclear(Note *n)
{
n->waitm = nil;
n->key = 0;
}
void
@ -127,8 +127,8 @@ runtime·notewakeup(Note *n)
M *mp;
do
mp = runtime·atomicloadp(&n->waitm);
while(!runtime·casp(&n->waitm, mp, (void*)LOCKED));
mp = runtime·atomicloadp((void**)&n->key);
while(!runtime·casp((void**)&n->key, mp, (void*)LOCKED));
// Successfully set waitm to LOCKED.
// What was it before?
@ -148,8 +148,8 @@ runtime·notesleep(Note *n)
{
if(m->waitsema == 0)
m->waitsema = runtime·semacreate();
if(!runtime·casp(&n->waitm, nil, m)) { // must be LOCKED (got wakeup)
if(n->waitm != (void*)LOCKED)
if(!runtime·casp((void**)&n->key, nil, m)) { // must be LOCKED (got wakeup)
if(n->key != LOCKED)
runtime·throw("notesleep - waitm out of sync");
return;
}
@ -176,8 +176,8 @@ runtime·notetsleep(Note *n, int64 ns)
m->waitsema = runtime·semacreate();
// Register for wakeup on n->waitm.
if(!runtime·casp(&n->waitm, nil, m)) { // must be LOCKED (got wakeup already)
if(n->waitm != (void*)LOCKED)
if(!runtime·casp((void**)&n->key, nil, m)) { // must be LOCKED (got wakeup already)
if(n->key != LOCKED)
runtime·throw("notetsleep - waitm out of sync");
return;
}
@ -212,10 +212,10 @@ runtime·notetsleep(Note *n, int64 ns)
// so that any notewakeup racing with the return does not
// try to grant us the semaphore when we don't expect it.
for(;;) {
mp = runtime·atomicloadp(&n->waitm);
mp = runtime·atomicloadp((void**)&n->key);
if(mp == m) {
// No wakeup yet; unregister if possible.
if(runtime·casp(&n->waitm, mp, nil))
if(runtime·casp((void**)&n->key, mp, nil))
return;
} else if(mp == (M*)LOCKED) {
// Wakeup happened so semaphore is available.

10
src/pkg/runtime/runtime.h
View File

@ -54,7 +54,7 @@ typedef struct Lock Lock;
typedef struct M M;
typedef struct P P;
typedef struct Mem Mem;
typedef union Note Note;
typedef struct Note Note;
typedef struct Slice Slice;
typedef struct Stktop Stktop;
typedef struct String String;
@ -163,10 +163,12 @@ struct Lock
// Used to be a union, but unions break precise GC.
uintptr key;
};
union Note
struct Note
{
uint32 key; // futex-based impl
M* waitm; // waiting M (sema-based impl)
// Futex-based impl treats it as uint32 key,
// while sema-based impl as M* waitm.
// Used to be a union, but unions break precise GC.
uintptr key;
};
struct String
{