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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E30C8C001DB for ; Mon, 7 Aug 2023 23:52:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229728AbjHGXwB (ORCPT ); Mon, 7 Aug 2023 19:52:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbjHGXwA (ORCPT ); Mon, 7 Aug 2023 19:52:00 -0400 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B8809E; Mon, 7 Aug 2023 16:51:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=m/8sfZtPepdEzWXIkozoxJYa1l+e++UeoE3yI8VOEBY=; b=D6MJQbL6py8+R+xYZewA8eGw1B XBTftyAMMQBIc8s3UgmrUn9FX+AdJqGdTy13apx0+YrOTbkJI2dpDYbWrtdqHVoVGvM8/iOB2ge1m wWS83yEQNuo888rvLN5MTEaQHy6oM76/pvwNR9+CPhQKH7nINO3jlV1q1hWa4v8jGgsI4Aok9JO/+ M1nR71q8CG8AtgolIuoYaohkQwHH75XmXQzIdRWDrP09Wwpbqotz5H+L7RTSyXvslI9oJjadHWBNJ Pk7JGc1XG/vznPdK6Spfno857Txfw/gGRJMrQC28XO+h5UG/Z7zfL92Ai/Pu6zGeIJRLFL2oXROk7 Nf2IaLRw==; Received: from [177.45.63.19] (helo=[192.168.1.111]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1qTA0t-00F9EE-2b; Tue, 08 Aug 2023 01:51:51 +0200 Message-ID: <3e73ae5e-8550-42a7-82de-bea1ca57fe1e@igalia.com> Date: Mon, 7 Aug 2023 20:51:42 -0300 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 01/14] futex: Clarify FUTEX2 flags To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, dvhart@infradead.org, dave@stgolabs.net, Andrew Morton , urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com, Arnd Bergmann , tglx@linutronix.de, linux-api@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, malteskarupke@web.de, axboe@kernel.dk References: <20230807121843.710612856@infradead.org> <20230807123322.814039156@infradead.org> Content-Language: en-US From: =?UTF-8?Q?Andr=C3=A9_Almeida?= In-Reply-To: <20230807123322.814039156@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Hi Peter, thank you for your patches. Em 07/08/2023 09:18, Peter Zijlstra escreveu: > sys_futex_waitv() is part of the futex2 series (the first and only so > far) of syscalls and has a flags field per futex (as opposed to flags > being encoded in the futex op). > > This new flags field has a new namespace, which unfortunately isn't > super explicit. Notably it currently takes FUTEX_32 and > FUTEX_PRIVATE_FLAG. > > Introduce the FUTEX2 namespace to clarify this > > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Thomas Gleixner Reviewed-by: André Almeida > --- > include/uapi/linux/futex.h | 16 +++++++++++++--- > kernel/futex/syscalls.c | 7 +++---- > 2 files changed, 16 insertions(+), 7 deletions(-) > > --- a/include/uapi/linux/futex.h > +++ b/include/uapi/linux/futex.h > @@ -44,10 +44,20 @@ > FUTEX_PRIVATE_FLAG) > > /* > - * Flags to specify the bit length of the futex word for futex2 syscalls. > - * Currently, only 32 is supported. > + * Flags for futex2 syscalls. > */ > -#define FUTEX_32 2 > + /* 0x00 */ > + /* 0x01 */ > +#define FUTEX2_SIZE_U32 0x02 > + /* 0x04 */ > + /* 0x08 */ > + /* 0x10 */ > + /* 0x20 */ > + /* 0x40 */ > +#define FUTEX2_PRIVATE FUTEX_PRIVATE_FLAG > + > +/* do not use */ > +#define FUTEX_32 FUTEX2_SIZE_U32 /* historical accident :-( */ > > /* > * Max numbers of elements in a futex_waitv array > --- a/kernel/futex/syscalls.c > +++ b/kernel/futex/syscalls.c > @@ -183,8 +183,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uad > return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3); > } > > -/* Mask of available flags for each futex in futex_waitv list */ > -#define FUTEXV_WAITER_MASK (FUTEX_32 | FUTEX_PRIVATE_FLAG) > +#define FUTEX2_VALID_MASK (FUTEX2_SIZE_U32 | FUTEX2_PRIVATE) > > /** > * futex_parse_waitv - Parse a waitv array from userspace > @@ -205,10 +204,10 @@ static int futex_parse_waitv(struct fute > if (copy_from_user(&aux, &uwaitv[i], sizeof(aux))) > return -EFAULT; > > - if ((aux.flags & ~FUTEXV_WAITER_MASK) || aux.__reserved) > + if ((aux.flags & ~FUTEX2_VALID_MASK) || aux.__reserved) > return -EINVAL; > > - if (!(aux.flags & FUTEX_32)) > + if (!(aux.flags & FUTEX2_SIZE_U32)) > return -EINVAL; > > futexv[i].w.flags = aux.flags; > >