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From: Cyrill Gorcunov via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH 1/1] fiber_cond: remove rlist_shift usages
Date: Tue, 2 Mar 2021 10:37:36 +0300	[thread overview]
Message-ID: <YD3rQB1d6mKeqKbV@grain> (raw)
In-Reply-To: <2ba579eef6f31d17a1670a6eaf31492366963ad9.1614637331.git.v.shpilevoy@tarantool.org>

On Mon, Mar 01, 2021 at 11:23:13PM +0100, Vladislav Shpilevoy wrote:
> @@ -94,7 +94,7 @@ fiber_cond_broadcast(struct fiber_cond *e)
>  {
>  	while (! rlist_empty(&e->waiters)) {
>  		struct fiber *f;
> -		f = rlist_shift_entry(&e->waiters, struct fiber, state);
> +		f = rlist_first_entry(&e->waiters, struct fiber, state);
>  		fiber_wakeup(f);
>  	}
>  }

The fiber_wakeup ignores

	if (f->flags & (FIBER_IS_READY | FIBER_IS_DEAD))
		return;

can't we hit the situation where fiber_cond_broadcast called with
dead fiber so that it won't be deleted from the list with new code?

Actually looking into fiber_loop code I see

static void
fiber_loop(MAYBE_UNUSED void *data)
{
	...
	fiber->flags |= FIBER_IS_DEAD;
	while (! rlist_empty(&fiber->wake)) {
		       struct fiber *f;
		       f = rlist_shift_entry(&fiber->wake, struct fiber,
					     state);
		       assert(f != fiber);
		       fiber_wakeup(f);
	}

so it should be safe with your patch, but just to make sure I didn't
miss something obvious.

  reply	other threads:[~2021-03-02  7:37 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-01 22:23 Vladislav Shpilevoy via Tarantool-patches
2021-03-02  7:37 ` Cyrill Gorcunov via Tarantool-patches [this message]
2021-03-02  7:54   ` Cyrill Gorcunov via Tarantool-patches
2021-03-02  9:04   ` Serge Petrenko via Tarantool-patches
2021-03-03 21:43     ` Vladislav Shpilevoy via Tarantool-patches
2021-03-03 21:37 ` Vladislav Shpilevoy via Tarantool-patches

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