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Bug: GC is not reentrant

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As the GC is not reentrant, finalizers should not be able to invoke it.
This commit is contained in:
Roberto Ierusalimschy
2021-12-13 10:41:17 -03:00
parent 1de95e97ef
commit 0bfc572e51
9 changed files with 57 additions and 27 deletions
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11
lgc.c
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@@ -906,16 +906,16 @@ static void GCTM (lua_State *L) {
if (!notm(tm)) { /* is there a finalizer? */
int status;
lu_byte oldah = L->allowhook;
int running = g->gcrunning;
int oldgcstp = g->gcstp;
g->gcstp = GCSTPGC; /* avoid GC steps */
L->allowhook = 0; /* stop debug hooks during GC metamethod */
g->gcrunning = 0; /* avoid GC steps */
setobj2s(L, L->top++, tm); /* push finalizer... */
setobj2s(L, L->top++, &v); /* ... and its argument */
L->ci->callstatus |= CIST_FIN; /* will run a finalizer */
status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0);
L->ci->callstatus &= ~CIST_FIN; /* not running a finalizer anymore */
L->allowhook = oldah; /* restore hooks */
g->gcrunning = running; /* restore state */
g->gcstp = oldgcstp; /* restore state */
if (l_unlikely(status != LUA_OK)) { /* error while running __gc? */
luaE_warnerror(L, "__gc metamethod");
L->top--; /* pops error object */
@@ -1502,9 +1502,11 @@ static void deletelist (lua_State *L, GCObject *p, GCObject *limit) {
*/
void luaC_freeallobjects (lua_State *L) {
global_State *g = G(L);
g->gcstp = GCSTPGC;
luaC_changemode(L, KGC_INC);
separatetobefnz(g, 1); /* separate all objects with finalizers */
lua_assert(g->finobj == NULL);
g->gcstp = 0;
callallpendingfinalizers(L);
deletelist(L, g->allgc, obj2gco(g->mainthread));
deletelist(L, g->finobj, NULL);
@@ -1647,6 +1649,7 @@ void luaC_runtilstate (lua_State *L, int statesmask) {
}
/*
** Performs a basic incremental step. The debt and step size are
** converted from bytes to "units of work"; then the function loops
@@ -1678,7 +1681,7 @@ static void incstep (lua_State *L, global_State *g) {
void luaC_step (lua_State *L) {
global_State *g = G(L);
lua_assert(!g->gcemergency);
if (g->gcrunning) { /* running? */
if (gcrunning(g)) { /* running? */
if(isdecGCmodegen(g))
genstep(L, g);
else