From patchwork Tue Dec 7 09:57:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 521947 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 47B88C433FE for ; Tue, 7 Dec 2021 09:59:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234706AbhLGKCs (ORCPT ); Tue, 7 Dec 2021 05:02:48 -0500 Received: from sin.source.kernel.org ([145.40.73.55]:51654 "EHLO sin.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234605AbhLGKCq (ORCPT ); Tue, 7 Dec 2021 05:02:46 -0500 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 sin.source.kernel.org (Postfix) with ESMTPS id 3BCA3CE1A2D; Tue, 7 Dec 2021 09:59:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B1DBC341CA; Tue, 7 Dec 2021 09:59:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638871153; bh=q0axvWjUR9JvT6UrywriXxF8qBrpbxelwDD6Sl6hDnc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IrwCcY8vYARI03xkh734NgeLRCaGeYHVJDuvLTXchr3/ARtLTOKzRaDYsGppPwFU7 wB1MbEfSgrC8XMu+KyMN2gmiqa13uiUwN+xnZuV7C2a1xTZsLla3A/zoRC5N8X7IeJ YOq3ygtgZbLxEXc34lsJFgGrxV985kupO4hJ335F4QCctkxWy7U0n2wu5vMnJbBDBG hsXMYJd3oa2iXYVKZIjISBdCTPXbW6rhRCbvlaJ85+kuQwOwAk51hExiGj+I+uK05I AlWPxRO3B4q+ZPK08CUKk23CQ/Lga8E4EymMyrOPlQWSNkSqTIi7HO32QEYUZ8gKMP 7wHF2dCu06bCg== From: Eric Biggers To: Alexander Viro , Benjamin LaHaise Cc: linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ramji Jiyani , Christoph Hellwig , Linus Torvalds , Oleg Nesterov , Jens Axboe , Martijn Coenen , stable@vger.kernel.org Subject: [PATCH v2 3/5] signalfd: use wake_up_pollfree() Date: Tue, 7 Dec 2021 01:57:24 -0800 Message-Id: <20211207095726.169766-4-ebiggers@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211207095726.169766-1-ebiggers@kernel.org> References: <20211207095726.169766-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Biggers wake_up_poll() uses nr_exclusive=1, so it's not guaranteed to wake up all non-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 Signed-off-by: Eric Biggers --- fs/signalfd.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/fs/signalfd.c b/fs/signalfd.c index 040e1cf905282..65ce0e72e7b95 100644 --- 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 {