Skip to content

TASK-189246 lock gc before traversing openupval #6

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
balupillai wants to merge 2 commits into
base: main
Choose a base branch
from
Open

TASK-189246 lock gc before traversing openupval #6

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
fdfcb11
TASK-189246 lock gc before traversing openupval
balupillai Feb 4, 2026
a118619
TASK-189246 use recursion to prevent deadlock
balupillai Feb 4, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 8 additions & 1 deletion src/lfunc.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -132,8 +132,12 @@ static void unlinkupval (UpVal *uv) {

void luaF_freeupval(lua_State *L, UpVal *uv)
{
if (uv->v != &uv->u.value) /* is it open? */
if (uv->v != &uv->u.value) { /* is it open? */
/* Block collector to prevent race with global trace traversing openupval */
luaC_blockcollector(L);
unlinkupval(uv); /* remove from open list */
luaC_unblockcollector(L);
}
luaM_free(L, LUA_MEM_UPVAL, uv); /* free upvalue */
}

Expand All @@ -144,6 +148,8 @@ void luaF_close (lua_State *L, StkId level) {
#if DEBUG_UPVAL
printf("close upval >= level %p\n", level);
#endif
/* Block collector to prevent race with global trace traversing openupval */
luaC_blockcollector(L);
while (L->openupval.u.l.next != &L->openupval &&
(uv = L->openupval.u.l.next)->v >= level) {
lua_assert(uv->v != &uv->u.value);
Expand All @@ -156,6 +162,7 @@ void luaF_close (lua_State *L, StkId level) {
// setobj(L, &uv->u.value, uv->v);
// luaC_linkupval(L, uv); /* link upvalue into `gcroot' list */
}
luaC_unblockcollector(L);
#if DEBUG_UPVAL
dumpopenupvals(L);
#endif
Expand Down
7 changes: 7 additions & 0 deletions src/lgc.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -337,6 +337,7 @@ static INLINE int try_block_mutators(lua_State *L)
{
uint32_t pending;
thr_State *pt;
int *recursion = get_recursion();

/* For the non-signal thread stoppage, take a write lock. Important that
* we do this before setting intend to stop, as we acquire the write
Expand All @@ -352,6 +353,8 @@ static INLINE int try_block_mutators(lua_State *L)
pthread_rwlock_wrlock(&trace_rwlock);
}

(*recursion)++;

/* advertise our intent to stop everyone; this prevents any mutators
* from returning from their respective barriers */
ck_pr_store_32(&G(L)->intend_to_stop, 1);
Expand Down Expand Up @@ -401,6 +404,10 @@ static INLINE int try_block_mutators(lua_State *L)

static INLINE void unblock_mutators(lua_State *L)
{
int *recursion = get_recursion();

(*recursion)--;

ck_pr_store_32(&G(L)->intend_to_stop, 0);
ck_pr_fence_memory();

Expand Down