Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71F6BC433FE for ; Mon, 13 Dec 2021 09:48:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236497AbhLMJrM (ORCPT ); Mon, 13 Dec 2021 04:47:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236080AbhLMJmu (ORCPT ); Mon, 13 Dec 2021 04:42:50 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F1B0C08E858; Mon, 13 Dec 2021 01:39:59 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4BAA9B80D1F; Mon, 13 Dec 2021 09:39:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 893CAC341C5; Mon, 13 Dec 2021 09:39:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1639388397; bh=wFDzVQg1q14Bxkecb1ysJs8MPnCV/er3LoVjFg6sZ+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j1/07eEvg4HwFg1F8L67B0iBO+2p0cV4XzRvK9zpZ37ijzBOjsCJVSXTJA03kZQ+q 62blu9PYFYDlJVOgTF78RwdTadAWXeJnV138X1jxmUw5Z+gUD/rAIS1q98JnQMLQzn 7BYFqo7lK5Zgqs8Ry2AkdTWgYwg47nkhcxdxyEek= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , "linux-kernel@vger.kernel.org, Linus Torvalds" , Eric Biggers , Linus Torvalds Subject: [PATCH 4.19 36/74] signalfd: use wake_up_pollfree() Date: Mon, 13 Dec 2021 10:30:07 +0100 Message-Id: <20211213092932.026311735@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211213092930.763200615@linuxfoundation.org> References: <20211213092930.763200615@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Biggers commit 9537bae0da1f8d1e2361ab6d0479e8af7824e160 upstream. wake_up_poll() uses nr_exclusive=1, so it's not guaranteed to wake up all exclusive waiters. Yet, POLLFREE *must* wake up all waiters. epoll and aio poll are fortunately not affected by this, but it's very fragile. Thus, the new function wake_up_pollfree() has been introduced. Convert signalfd to use wake_up_pollfree(). Reported-by: Linus Torvalds Fixes: d80e731ecab4 ("epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211209010455.42744-4-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman --- fs/signalfd.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) --- a/fs/signalfd.c +++ b/fs/signalfd.c @@ -35,17 +35,7 @@ void signalfd_cleanup(struct sighand_struct *sighand) { - wait_queue_head_t *wqh = &sighand->signalfd_wqh; - /* - * The lockless check can race with remove_wait_queue() in progress, - * but in this case its caller should run under rcu_read_lock() and - * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return. - */ - if (likely(!waitqueue_active(wqh))) - return; - - /* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */ - wake_up_poll(wqh, EPOLLHUP | POLLFREE); + wake_up_pollfree(&sighand->signalfd_wqh); } struct signalfd_ctx {