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Avoid deadlock when finalizer lock is held during gc. 

From-SVN: r169112
This commit is contained in:
Ian Lance Taylor 2011-01-21 23:33:52 +00:00
parent 723553bdc1
commit cf606aeb06
3 changed files with 41 additions and 2 deletions
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9
libgo/runtime/go-go.c
View File

@ -315,6 +315,15 @@ gc_stop_handler (int sig __attribute__ ((unused)))
return;
}
if (__sync_bool_compare_and_swap (&pm->holds_finlock, 1, 1))
{
/* Similarly, we can't interrupt the thread while it holds the
finalizer lock. Otherwise we can get into a deadlock when
mark calls runtime_walkfintab. */
__sync_bool_compare_and_swap (&pm->gcing_for_finlock, 0, 1);
return;
}
stop_for_gc ();
}

32
libgo/runtime/mfinal.c
View File

@ -106,9 +106,13 @@ runtime_addfinalizer(void *p, void (*f)(void*), const struct __go_func_type *ft)
e->ft = ft;
}
if(!__sync_bool_compare_and_swap(&m->holds_finlock, 0, 1))
runtime_throw("finalizer deadlock");
runtime_lock(&finlock);
if(!runtime_mlookup(p, &base, nil, nil, &ref) || p != base) {
runtime_unlock(&finlock);
__sync_bool_compare_and_swap(&m->holds_finlock, 1, 0);
runtime_throw("addfinalizer on invalid pointer");
}
if(f == nil) {
@ -116,12 +120,12 @@ runtime_addfinalizer(void *p, void (*f)(void*), const struct __go_func_type *ft)
lookfintab(&fintab, p, 1);
*ref &= ~RefHasFinalizer;
}
runtime_unlock(&finlock);
return;
goto unlock;
}
if(*ref & RefHasFinalizer) {
runtime_unlock(&finlock);
__sync_bool_compare_and_swap(&m->holds_finlock, 1, 0);
runtime_throw("double finalizer");
}
*ref |= RefHasFinalizer;
@ -156,7 +160,14 @@ runtime_addfinalizer(void *p, void (*f)(void*), const struct __go_func_type *ft)
}
addfintab(&fintab, p, e);
unlock:
runtime_unlock(&finlock);
__sync_bool_compare_and_swap(&m->holds_finlock, 1, 0);
if(__sync_bool_compare_and_swap(&m->gcing_for_finlock, 1, 0)) {
__go_run_goroutine_gc(200);
}
}
// get finalizer; if del, delete finalizer.
@ -166,9 +177,18 @@ runtime_getfinalizer(void *p, bool del)
{
Finalizer *f;
if(!__sync_bool_compare_and_swap(&m->holds_finlock, 0, 1))
runtime_throw("finalizer deadlock");
runtime_lock(&finlock);
f = lookfintab(&fintab, p, del);
runtime_unlock(&finlock);
__sync_bool_compare_and_swap(&m->holds_finlock, 1, 0);
if(__sync_bool_compare_and_swap(&m->gcing_for_finlock, 1, 0)) {
__go_run_goroutine_gc(201);
}
return f;
}
@ -178,6 +198,9 @@ runtime_walkfintab(void (*fn)(void*), void (*scan)(byte *, int64))
void **key;
void **ekey;
if(!__sync_bool_compare_and_swap(&m->holds_finlock, 0, 1))
runtime_throw("finalizer deadlock");
scan((byte*)&fintab, sizeof fintab);
runtime_lock(&finlock);
key = fintab.key;
@ -186,4 +209,9 @@ runtime_walkfintab(void (*fn)(void*), void (*scan)(byte *, int64))
if(*key != nil && *key != ((void*)-1))
fn(*key);
runtime_unlock(&finlock);
__sync_bool_compare_and_swap(&m->holds_finlock, 1, 0);
if(__sync_bool_compare_and_swap(&m->gcing_for_finlock, 1, 0)) {
runtime_throw("walkfintab not called from gc");
}
}

2
libgo/runtime/runtime.h
View File

@ -97,6 +97,8 @@ struct M
int32 locks;
int32 nomemprof;
int32 gcing_for_prof;
int32 holds_finlock;
int32 gcing_for_finlock;
MCache *mcache;
/* For the list of all threads. */