runtime: lock finalizer table accesses

R=r
CC=golang-dev
https://golang.org/cl/462043

diff --git a/src/pkg/runtime/mfinal.c b/src/pkg/runtime/mfinal.c
index 95917472314747d23b17b601ae5692c220461bb9..53a2a4bbe9c2326e8f7693a60c2f19fe12b2fac6 100644 (file)
--- a/src/pkg/runtime/mfinal.c
+++ b/src/pkg/runtime/mfinal.c
@@ -5,6 +5,8 @@
 #include "runtime.h"
 #include "malloc.h"
 
+Lock finlock;
+
 // Finalizer hash table.  Direct hash, linear scan, at most 3/4 full.
 // Table size is power of 3 so that hash can be key % max.
 // Key[i] == (void*)-1 denotes free but formerly occupied entry
@@ -97,18 +99,24 @@ addfinalizer(void *p, void (*f)(void*), int32 nret)
        uint32 *ref;
        byte *base;
 
-       if(!mlookup(p, &base, nil, nil, &ref) || p != base)
+       lock(&finlock);
+       if(!mlookup(p, &base, nil, nil, &ref) || p != base) {
+               unlock(&finlock);
                throw("addfinalizer on invalid pointer");
+       }
        if(f == nil) {
                if(*ref & RefHasFinalizer) {
-                       getfinalizer(p, 1, nil);
+                       lookfintab(&fintab, p, 1, nil);
                        *ref &= ~RefHasFinalizer;
                }
+               unlock(&finlock);
                return;
        }
 
-       if(*ref & RefHasFinalizer)
+       if(*ref & RefHasFinalizer) {
+               unlock(&finlock);
                throw("double finalizer");
+       }
        *ref |= RefHasFinalizer;
 
        if(fintab.nkey >= fintab.max/2+fintab.max/4) {
@@ -141,6 +149,7 @@ addfinalizer(void *p, void (*f)(void*), int32 nret)
        }
 
        addfintab(&fintab, p, f, nret);
+       unlock(&finlock);
 }
 
 // get finalizer; if del, delete finalizer.
@@ -148,5 +157,10 @@ addfinalizer(void *p, void (*f)(void*), int32 nret)
 void*
 getfinalizer(void *p, bool del, int32 *nret)
 {
-       return lookfintab(&fintab, p, del, nret);
+       void *f;
+       
+       lock(&finlock);
+       f = lookfintab(&fintab, p, del, nret);
+       unlock(&finlock);
+       return f;
 }