From nobody Fri Feb 13 17:33:12 2026 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 4DE72E7D0A2 for ; Thu, 21 Sep 2023 20:47:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232481AbjIUUrf (ORCPT ); Thu, 21 Sep 2023 16:47:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231927AbjIUUrI (ORCPT ); Thu, 21 Sep 2023 16:47:08 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE9837E4F3; Thu, 21 Sep 2023 10:36:05 -0700 (PDT) Date: Thu, 21 Sep 2023 17:36:02 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1695317764; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cZ+AWsu/It5qMoqLvWyHRu3tp7dd43Yf5izBLfEk20A=; b=j6sJNM6oqKgpQj6qMLdn+nqzbYwE4fu6QpYJICqWKxzEnnxo7gGo2CtKzvosUzm/Rj1QmK f3pLQqm3IwN1J3uJIcEtBuNN2CPpZPBlOB7/exIabkUVBd4QeyW2uq1LxpVmKCNSll00Jd m912p66grCOfKJGD0Bn2jpymw+DJpymJK/jpfzJ6FikbGNoJmWkh/Po1mzXGLJJ42Od/mT qU8YOaiQ7gc5BiCmVZE1EI2PZuObyh6GZh5sMMSC/Glz8+gRergWwQHbE7g7c1mT30MWjO bLKOyFKcg1hDHZIDMjWC+RM4qsNbC9OKKZt5b1OgFdl0rLrFw0aefP37OvdfSQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1695317764; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cZ+AWsu/It5qMoqLvWyHRu3tp7dd43Yf5izBLfEk20A=; b=CAddA7LF3Yscb8zsb/+4tQ37vZoAFf+VyGH0/hI3WoddMS120kKSdkuK/KIxQtcBl3NRUU WwQ2HuwsD6USA0Cg== From: "tip-bot2 for peterz@infradead.org" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] futex: FLAGS_STRICT Cc: andrealmeid@igalia.com, "Peter Zijlstra (Intel)" , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20230921105248.048643656@noisy.programming.kicks-ass.net> References: <20230921105248.048643656@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Message-ID: <169531776286.27769.7382358930466919741.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/core branch of tip: Commit-ID: 43adf844951084c266f172561f84c5f8120dd60b Gitweb: https://git.kernel.org/tip/43adf844951084c266f172561f84c5f81= 20dd60b Author: peterz@infradead.org AuthorDate: Thu, 21 Sep 2023 12:45:11 +02:00 Committer: Peter Zijlstra CommitterDate: Thu, 21 Sep 2023 19:22:07 +02:00 futex: FLAGS_STRICT The current semantics for futex_wake() are a bit loose, specifically asking for 0 futexes to be woken actually gets you 1. Adding a !nr check to sys_futex_wake() makes that it would return 0 for unaligned futex words, because that check comes in the shared futex_wake() function. Adding the !nr check there, would affect the legacy sys_futex() semantics. Hence frob a flag :-( Suggested-by: Andr=C3=A9 Almeida Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230921105248.048643656@noisy.programming.= kicks-ass.net --- kernel/futex/futex.h | 21 +++++++++++---------- kernel/futex/syscalls.c | 2 +- kernel/futex/waitwake.c | 3 +++ 3 files changed, 15 insertions(+), 11 deletions(-) diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index a3f1fce..0e7821a 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -17,25 +17,26 @@ * Futex flags used to encode options to functions and preserve them across * restarts. */ -#define FLAGS_SIZE_8 0x00 -#define FLAGS_SIZE_16 0x01 -#define FLAGS_SIZE_32 0x02 -#define FLAGS_SIZE_64 0x03 +#define FLAGS_SIZE_8 0x0000 +#define FLAGS_SIZE_16 0x0001 +#define FLAGS_SIZE_32 0x0002 +#define FLAGS_SIZE_64 0x0003 =20 -#define FLAGS_SIZE_MASK 0x03 +#define FLAGS_SIZE_MASK 0x0003 =20 #ifdef CONFIG_MMU -# define FLAGS_SHARED 0x10 +# define FLAGS_SHARED 0x0010 #else /* * NOMMU does not have per process address space. Let the compiler optimize * code away. */ -# define FLAGS_SHARED 0x00 +# define FLAGS_SHARED 0x0000 #endif -#define FLAGS_CLOCKRT 0x20 -#define FLAGS_HAS_TIMEOUT 0x40 -#define FLAGS_NUMA 0x80 +#define FLAGS_CLOCKRT 0x0020 +#define FLAGS_HAS_TIMEOUT 0x0040 +#define FLAGS_NUMA 0x0080 +#define FLAGS_STRICT 0x0100 =20 /* FUTEX_ to FLAGS_ */ static inline unsigned int futex_to_flags(unsigned int op) diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 7049a52..4739892 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -333,7 +333,7 @@ SYSCALL_DEFINE4(futex_wake, if (!futex_validate_input(flags, mask)) return -EINVAL; =20 - return futex_wake(uaddr, flags, nr, mask); + return futex_wake(uaddr, FLAGS_STRICT | flags, nr, mask); } =20 #ifdef CONFIG_COMPAT diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c index fa97577..ceb05b8 100644 --- a/kernel/futex/waitwake.c +++ b/kernel/futex/waitwake.c @@ -155,6 +155,9 @@ int futex_wake(u32 __user *uaddr, unsigned int flags, i= nt nr_wake, u32 bitset) if (unlikely(ret !=3D 0)) return ret; =20 + if ((flags & FLAGS_STRICT) && !nr_wake) + return 0; + hb =3D futex_hash(&key); =20 /* Make sure we really have tasks to wakeup */