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 CECC7C4332F for ; Wed, 13 Dec 2023 00:15:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B13EE8D000F; Tue, 12 Dec 2023 19:15:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A9CB78D0009; Tue, 12 Dec 2023 19:15:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93CD18D000F; Tue, 12 Dec 2023 19:15:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 7E7908D0009 for ; Tue, 12 Dec 2023 19:15:09 -0500 (EST) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 59D4BA0ADF for ; Wed, 13 Dec 2023 00:15:09 +0000 (UTC) X-FDA: 81559875138.23.A64E563 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf09.hostedemail.com (Postfix) with ESMTP id A270714000A for ; Wed, 13 Dec 2023 00:15:07 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf09.hostedemail.com: domain of "SRS0=4TYM=HY=goodmis.org=rostedt@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=4TYM=HY=goodmis.org=rostedt@kernel.org" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1702426507; 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=7HCj4GPL3G0/6AcWfsWYLwBIGOCWIo02YBoYrkdn1XE=; b=P52/gPUFI8nQK+CilSfawHf98KtE1DeMv9CJjy9tccrJr+mHcZ5D8nByAlnAzsv4sbSaBG Al9ZzOgNhkNYdmQLDneuuWrAoe2jHD1RyXydDOtkqB7JsMCHxnimUrnw4WiblOXMwM0xSp o6KBJJB/z1KIjnYrqiSRUnE2HBrwIjI= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf09.hostedemail.com: domain of "SRS0=4TYM=HY=goodmis.org=rostedt@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=4TYM=HY=goodmis.org=rostedt@kernel.org" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1702426507; a=rsa-sha256; cv=none; b=3RMoo0mYfRJ2cbponPPLj2sY/f+ByqF0z6flWOaqCF2HVJTUIrOxGcUaHEDP0nxtTaxt8x FgpjZV/+wbW7Wcf8ZGHleVOaXv8TNeiRXpl59IQL3xkRffZjNxCH6Ww2KGn0x0LrxEfqfa Pajf+eEXG1hhXEtxyWrDDDTKyf9+hsM= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 648F761A59; Wed, 13 Dec 2023 00:15:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 724A5C433C8; Wed, 13 Dec 2023 00:15:03 +0000 (UTC) Date: Tue, 12 Dec 2023 19:15:46 -0500 From: Steven Rostedt To: Alexander Graf Cc: , , , , , , , , Eric Biederman , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , "Rob Herring" , "Andrew Morton" , Mark Rutland , "Tom Lendacky" , Ashish Kalra , James Gowans , Stanislav Kinsburskii , , , , Anthony Yznaga , Usama Arif , David Woodhouse , Benjamin Herrenschmidt Subject: Re: [PATCH 08/15] tracing: Introduce names for ring buffers Message-ID: <20231212191546.603c0703@gandalf.local.home> In-Reply-To: <20231213000452.88295-9-graf@amazon.com> References: <20231213000452.88295-1-graf@amazon.com> <20231213000452.88295-9-graf@amazon.com> X-Mailer: Claws Mail 3.19.1 (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-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: A270714000A X-Stat-Signature: ehj345tbufics5enenqttkbajw145fw3 X-HE-Tag: 1702426507-845925 X-HE-Meta: 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 gLKtb4Qb gjJYAtebMFBEpqUXnei4dYJHd3ydF/Q4Pkbb3nTT7LRiJKueLLGJ7LPUF9CAmiyYG+OV7paxXbDffD8YG05JaNG86mACSA8MpC1tXfkqTD+aes1QWhBWeerCd6Aza79+rbXj4/mwc0LoBhlAc/RlWDPo6NorbyALjUYm9bO8tVcTm7uq8AZCw9XXfQc3AeFg8w9xuK29Ab3GmNSOwba2n0+B5+Df+J1oniibskKPAxK7X936OoXTapB2Vc1U0tnpGwspm/VP/zUQViDoJs88dDmpZNXUdgcxHGhUHjxZv6HMJg/uvQx02Eb6HP+9//MLhVzSPm2m1hlz4RkOSuu54SD1VWHo1GvKhG2d1 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 Wed, 13 Dec 2023 00:04:45 +0000 Alexander Graf wrote: > With KHO (Kexec HandOver), we want to preserve trace buffers across > kexec. To carry over their state between kernels, the kernel needs a > common handle for them that exists on both sides. As handle we introduce > names for ring buffers. In a follow-up patch, the kernel can then use > these names to recover buffer contents for specific ring buffers. > Is there a way to use the trace_array name instead? The trace_array is the structure that represents each tracing instance. And it already has a name field. And if you can get the associated ring buffer from that too. struct trace_array *tr; tr->array_buffer.buffer tr->name When you do: mkdir /sys/kernel/tracing/instance/foo You create a new trace_array instance where tr->name = "foo" and allocates the buffer for it as well. -- Steve