Re: [Tarantool-patches] [PATCH luajit 3/3] Follow-up fix for stack overflow handling cleanup.

[Sergey Kaplun via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Hi, Maksim!
Thanks for the patch!
LGTM, except an insignificant nit below.

On 18.11.23, Maksim Kokryashkin wrote:
> From: Mike Pall <mike>
> 
> (cherry-picked from commit aa6b15c1a8922848bd6f596ba384824ca3fe0f5f)
> 
> The stack overflow error is thrown in `lj_state_growstack` only
> if the coroutine status is `OK`, however, stack overflow can
> happen on a yielded coroutine too. This patch fixes the condition
> for status, so now the error thrown on yielded coroutines too.
> 
> Maxim Kokryashkin:
> * added the description and the test for the patch
> 
> Part of tarantool/tarantool#9145
> ---
>  src/lj_state.c                                |  2 +-
>  .../lj-962-premature-stack-overflow.test.c    | 23 +++++++++++++++++++
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/src/lj_state.c b/src/lj_state.c
> index d8a5134c..01d4901a 100644
> --- a/src/lj_state.c
> +++ b/src/lj_state.c
> @@ -126,7 +126,7 @@ void LJ_FASTCALL lj_state_growstack(lua_State *L, MSize need)
>      if (L->stacksize > LJ_STACK_MAXEX)
>        lj_err_throw(L, LUA_ERRERR);  /* Does not invoke an error handler. */
>      /* 1. We are _at_ the limit after the last growth. */
> -    if (!L->status) {  /* 2. Throw 'stack overflow'. */
> +    if (L->status < LUA_ERRRUN) {  /* 2. Throw 'stack overflow'. */
>        L->status = LUA_ERRRUN;  /* Prevent ending here again for pushed msg. */
>        lj_err_msg(L, LJ_ERR_STKOV);  /* May invoke an error handler. */
>      }
> diff --git a/test/tarantool-c-tests/lj-962-premature-stack-overflow.test.c b/test/tarantool-c-tests/lj-962-premature-stack-overflow.test.c
> index 0873636a..7a03038b 100644
> --- a/test/tarantool-c-tests/lj-962-premature-stack-overflow.test.c
> +++ b/test/tarantool-c-tests/lj-962-premature-stack-overflow.test.c
> @@ -21,6 +21,20 @@ static int fill_stack(lua_State *L)
>  	return 1;
>  }
>  
> +static int immediate_yield(lua_State *L)
> +{
> +	return lua_yield(L, 0);
> +}
> +
> +static int overflow_suspended_coro(lua_State *L)
> +{
> +	lua_State *newL = lua_newthread(L);
> +	lua_pushcfunction(newL, immediate_yield);
> +	lua_resume(newL, 0);
> +	fill_stack(newL);
> +	return 1;

Why do we return something from this Lua function? What is this value on
Lua stack?

> +}
> +
>  static int premature_stackoverflow(void *test_state)
>  {
>  	lua_State *L = test_state;
> @@ -29,11 +43,20 @@ static int premature_stackoverflow(void *test_state)
>  	return TEST_EXIT_SUCCESS;
>  }
>  
> +static int stackoverflow_on_suspended_coro(void *test_state)
> +{
> +	lua_State *L = test_state;
> +	int status = lua_cpcall(L, overflow_suspended_coro, NULL);
> +	assert_true(status == LUA_ERRRUN);
> +	return TEST_EXIT_SUCCESS;
> +}
> +
>  int main(void)
>  {
>  	lua_State *L = utils_lua_init();
>  	const struct test_unit tgroup[] = {
>  		test_unit_def(premature_stackoverflow),
> +		test_unit_def(stackoverflow_on_suspended_coro),
>  	};
>  	const int test_result = test_run_group(tgroup, L);
>  	utils_lua_close(L);
> -- 
> 2.39.3 (Apple Git-145)
> 

-- 
Best regards,
Sergey Kaplun