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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BDE2DC27C4F for ; Sun, 30 Jun 2024 12:41:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BFC256B0082; Sun, 30 Jun 2024 08:40:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BAC6E6B0083; Sun, 30 Jun 2024 08:40:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A73AC6B0085; Sun, 30 Jun 2024 08:40:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 882AE6B0082 for ; Sun, 30 Jun 2024 08:40:59 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 10C401215D3 for ; Sun, 30 Jun 2024 12:40:59 +0000 (UTC) X-FDA: 82287514638.17.3DE563A Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf15.hostedemail.com (Postfix) with ESMTP id 52236A000A for ; Sun, 30 Jun 2024 12:40:57 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf15.hostedemail.com: domain of "SRS0=Ctq3=OA=goodmis.org=rostedt@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=Ctq3=OA=goodmis.org=rostedt@kernel.org" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1719751238; h=from:from:sender: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=m58lk15WiypanWjI5vkiZiyULsPPA9WcxWq2EodqmHY=; b=ht/bdkc8Lz+WIFYmv3a/6yphtWmmN71iu6+PfROXL+Mc/2L2kTVW3X5xg5ajv9YxNduJXn jf++dssKlwHuPwd1mimqos/qsbybeazGISu2qhCYdbmWSK8J1T5giosqg3u8GaMkmWiEsR tAab8pLe5tsordtE1VhsYVb3hBTUVWc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1719751238; a=rsa-sha256; cv=none; b=gjuTZ7ABDdQt/mOH5MOHq0FwMOADk3tWZ4zrcoLqUxzt6Uxp66Dc9UouIJU8ngkbqYVkyD XboEnP0BatxddjfhjWdVA52VjcEjuFUz3EyklAnahV0YdKyZgFLDlezhgRMl69HJnuqoyZ fxCdHB31EEL6p+2Xwve1z4WL+HHF+Go= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf15.hostedemail.com: domain of "SRS0=Ctq3=OA=goodmis.org=rostedt@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=Ctq3=OA=goodmis.org=rostedt@kernel.org" Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 544C860D24; Sun, 30 Jun 2024 12:40:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79949C2BD10; Sun, 30 Jun 2024 12:40:54 +0000 (UTC) Date: Sun, 30 Jun 2024 08:40:53 -0400 From: Steven Rostedt To: "Dmitry V. Levin" Cc: Vincent Donnefort , mhiramat@kernel.org, mathieu.desnoyers@efficios.com, kernel-team@android.com, rdunlap@infradead.org, rppt@kernel.org, david@redhat.com, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: [PATCH v23 3/5] tracing: Allow user-space mapping of the ring-buffer Message-ID: <20240630084053.0b506916@rorschach.local.home> In-Reply-To: <20240630105322.GA17573@altlinux.org> References: <20240510140435.3550353-1-vdonnefort@google.com> <20240510140435.3550353-4-vdonnefort@google.com> <20240630105322.GA17573@altlinux.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 52236A000A X-Stat-Signature: nzjzc6z6s9y83tpxpoufgfgs1n4r6ih4 X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1719751257-915859 X-HE-Meta: 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 rePwlG5G VODZRxA3HFXf6zQ4ms8k96s2TUzu3rHR3VsTQ6+ArFwiG/MGu+AUswpsktKuCH5aEAiJvlgGi9sBvLP+owrCKry0UgXcrnQemM6/Q3mr6Vee4Mfy3QvDFdUZuKNZD61F5qP3PSu+8U0lNkAjbeTzjQH+TlkunA113Vjv4gw3ja32uF7RN8O7lnKrFQLZpjOinrrnJhhudrspA1PKncL8y9g9q760gM3P//nLZiKngHSKopKrMfQ45PXFAKgXtpQjzcyWP X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 30 Jun 2024 13:53:23 +0300 "Dmitry V. Levin" wrote: > On Fri, May 10, 2024 at 03:04:32PM +0100, Vincent Donnefort wrote: > [...] > > diff --git a/include/uapi/linux/trace_mmap.h b/include/uapi/linux/trace_mmap.h > > index b682e9925539..bd1066754220 100644 > > --- a/include/uapi/linux/trace_mmap.h > > +++ b/include/uapi/linux/trace_mmap.h > > @@ -43,4 +43,6 @@ struct trace_buffer_meta { > > __u64 Reserved2; > > }; > > > > +#define TRACE_MMAP_IOCTL_GET_READER _IO('T', 0x1) > > + > > I'm sorry but among all the numbers this one was probably the least > fortunate choice because it collides with TCGETS on most of architectures. Hmm, that is unfortunate. > > For example, this is how strace output would look like when > TRACE_MMAP_IOCTL_GET_READER support is added: > > $ strace -e ioctl stty > ioctl(0, TCGETS or TRACE_MMAP_IOCTL_GET_READER, {c_iflag=ICRNL|IXON, c_oflag=NL0|CR0|TAB0|BS0|VT0|FF0|OPOST|ONLCR, c_cflag=B38400|CS8|CREAD, c_lflag=ISIG|ICANON|ECHO|ECHOE|ECHOK|IEXTEN|ECHOCTL|ECHOKE, ...}) = 0 > > Even though ioctl numbers are inherently not unique, TCGETS is > a very traditional one, so it would be great if you could change > TRACE_MMAP_IOCTL_GET_READER to avoid this collision. > > Given that _IO('T', 0x1) is _IOC(_IOC_NONE, 'T', 0x1, 0), > something like _IOC(_IOC_NONE, 'T', 0x1, 0x1) should be OK. Well, it may not be too late to update this as it hasn't been officially released in 6.10 yet. It's still only in the -rc and the library doesn't rely on this yet (I've been holding off until 6.10 was officially released before releasing the library that uses it). I can send a patch this week to update it. Or feel free to send a patch yourself. Thanks, -- Steve