From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DEE90C4332D for ; Mon, 1 Mar 2021 16:44:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB03865030 for ; Mon, 1 Mar 2021 16:44:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235109AbhCAQnD (ORCPT ); Mon, 1 Mar 2021 11:43:03 -0500 Received: from mail.kernel.org ([198.145.29.99]:43236 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232952AbhCAQgt (ORCPT ); Mon, 1 Mar 2021 11:36:49 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 409BA64F6B; Mon, 1 Mar 2021 16:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614615978; bh=Ufwgbib4tnmfpKGDOy+QmSp0NroTZgDRb+4rXYsHuSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=no972zj+3gPmH9mxRzx7bddYkkVw6gwh8LYkM6YGoVP+87HXVeS77MKqCMhld0bnU 9NeoP/0b64tFzpcV3ejNeN+TTDWrAykesWMAr7RwxQXs344lUaPySUOIMDcz1rfOvG 6PABoKxEN5jBgH/xWDDZNoyyw+ZvgHrnRqwZG/gA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiaoming Ni , Lee Jones Subject: [PATCH 4.9 127/134] futex: fix dead code in attach_to_pi_owner() Date: Mon, 1 Mar 2021 17:13:48 +0100 Message-Id: <20210301161019.841984983@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161013.585393984@linuxfoundation.org> References: <20210301161013.585393984@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: stable@vger.kernel.org From: Thomas Gleixner The handle_exit_race() function is defined in commit 9c3f39860367 ("futex: Cure exit race"), which never returns -EBUSY. This results in a small piece of dead code in the attach_to_pi_owner() function: int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ ... if (ret == -EBUSY) *exiting = p; /* dead code */ The return value -EBUSY is added to handle_exit_race() in upsteam commit ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting"). This commit was incorporated into v4.9.255, before the function handle_exit_race() was introduced, whitout Modify handle_exit_race(). To fix dead code, extract the change of handle_exit_race() from commit ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting"), re-incorporated. Lee writes: This commit takes the remaining functional snippet of: ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") ... and is the correct fix for this issue. Fixes: 9c3f39860367 ("futex: Cure exit race") Cc: stable@vger.kernel.org # v4.9.258 Signed-off-by: Xiaoming Ni Reviewed-by: Lee Jones Signed-off-by: Greg Kroah-Hartman --- kernel/futex.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1207,11 +1207,11 @@ static int handle_exit_race(u32 __user * u32 uval2; /* - * If the futex exit state is not yet FUTEX_STATE_DEAD, wait - * for it to finish. + * If the futex exit state is not yet FUTEX_STATE_DEAD, tell the + * caller that the alleged owner is busy. */ if (tsk && tsk->futex_state != FUTEX_STATE_DEAD) - return -EAGAIN; + return -EBUSY; /* * Reread the user space value to handle the following situation: