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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6E5A2CCFA13 for ; Thu, 30 Apr 2026 20:42:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=3vbJaL0qvtGk1NC0ztOfHKQqU3avaZZm4uoH47YILVE=; b=bkISREAkeZIR3eeyUFn7BsC77Z fqQstWNne+mTcZMQuGCZQyknnlEv3i5fPadQNOcwg+V484XMMLQw1v4OvCD6FYKQ+C51F/a+BIREl PnKAcT4yimHpfq1CofHU5m2bZqmOV6sBZZDGisKFn/PMA5EuQJRZMJUl9IKR3l2s1MaYHmeRd40ev 6I2yPgA/qhbZfnNxmmMTs15Isabg1hrSTuYpQvVXujZD4nzOUttoWpeY4reLNVgqVQmyz5J6fscuU uNjE+eg16RzVyYt+Z3rqVHwCGtXotNoZkZjmm6Hf1x+/n8C6n6/enHSM9BJOwwfd6h2aMHNAQ9byu u02Zj2hQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wIYDY-00000005vuU-0gy6; Thu, 30 Apr 2026 20:42:40 +0000 Received: from mail-pl1-x62d.google.com ([2607:f8b0:4864:20::62d]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wIYDV-00000005vu6-0qL0 for kexec@lists.infradead.org; Thu, 30 Apr 2026 20:42:38 +0000 Received: by mail-pl1-x62d.google.com with SMTP id d9443c01a7336-2b46da8c48eso9855ad.1 for ; Thu, 30 Apr 2026 13:42:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777581756; x=1778186556; darn=lists.infradead.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=3vbJaL0qvtGk1NC0ztOfHKQqU3avaZZm4uoH47YILVE=; b=FKsfw8fpH4Z6+pHXIOiCEJ7SE7vDk2kUuyRiBMTOfl77MstUUOD/lj4iF3QOmzSmc5 oYcSRkK7/uW8Kvn7u/D27ddJCqKirLZdVEQlxGY8WpLddHKB/pp2Fk91C8YcNN095nbF UdVBB17g1063pn8asG1I30pUSWfyKHbX13f/wme6xdz5si+ID146jSNDckhmURxc/R7s lzWqqVGLoCNk2cGhSnJbBqrFBKWfrakAC+Z2Mbbabon3XvllHnNH5XJae5HPaS7CkfXt dbfvGpb3YT8rPMQaKeMOpoqYCGY51/DAechijKt6W9qsA3WFjx3cQ4LAT1rADy5x8Co1 TQRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777581756; x=1778186556; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3vbJaL0qvtGk1NC0ztOfHKQqU3avaZZm4uoH47YILVE=; b=iZsuoA61u3l/u3/Q3LLjnBCm9PV6LlW3zNV9UYLO7hToecu3+X8aRyGFT6yEe1Xm0n oxvmL4JzqS4bknTpb5WVd2gCsu8iOLi8hQ5WUp+d/VZfUwHoWO7upK24HzY6rxcUUBT7 pRBhcIcj8ohX68B+6cwmOJD8OX+svAK+qg2y+4+i7+Yg2/C+iI85vBCb6mc87q4kijOJ 6NAMKtg1DEGgpl591StjNi52B5qxbfinQCi4BEi6+fkaMuvH5iBNgGS0zNMmum7OsYjC ttKMdv+PgYA5QQxFHL7tyJVPCkbz6PmKCYpCpUskZMUxqh4nIWIziqh//rNPf4I4EAEk do9w== X-Forwarded-Encrypted: i=1; AFNElJ9eZVDlQwd/3j4FsMzyVjtZXAR4jSUnW9bIDsmlPBexzc2hyDDEhePjDJQwQ0CJGO888OWMCA==@lists.infradead.org X-Gm-Message-State: AOJu0YzHk/YJ8quuzi9aQdaTKyAuP+kgXI+XjXeJ/YaOXdiHurWgoaoc 8Xv7ZCb0Af8s17SsQd7dYj5RYaEPZiZDk9LfEBmb0L21utXwZojWngHRV4ZDYm4YCQ== X-Gm-Gg: AeBDiessksHzjXKxLbm+0gKwP1XQwBT9TVA4aS+KfQD4DRXyizYh5h/WaJs5pNgHEuD DZW0R8zMTiKGSjfNWdnb38o4SKoMG8/uCiRPvdze3SDmWmU8h7FxCVGVfbDWQrMwE0hhfaR0lX1 UDgKDNQ8BPqeSMTVav85c30jmq2ikmclzb1Pu13BWR3HQvT92rELD4usOS5ESv33t4iynpgmK4k 1RxuyibjiKZHShQi0UP/+9x4Lc8/fQJ10X+Ao7FdfGSKjmDH98bcVgJaO2qH/ZQThmaFUjCFTQr 8H64OyuadVDRRJPIEniIU8UJ4BIV2qAUwNB7AlQ0arNIgxWxYK7frXlPd8VV6cCTFmDsAhW1WWH 2trjqoSQYEpQTdXrxPmztfNvh+uJBeWJXnj0WVYcQNoGJcm+ncA27Q7R8xchiomY7LwlQu4YQSE 9CUI/rtNUqePwDuVMvSxj2eaJ/gCdvQOFan2SXlRuDJvOLW21qkSvi5CStRXCnZuAgXMc4vpY1A G0fWfm3IA== X-Received: by 2002:a17:902:efd3:b0:2ae:575f:3755 with SMTP id d9443c01a7336-2b9cde4ae98mr575255ad.20.1777581755636; Thu, 30 Apr 2026 13:42:35 -0700 (PDT) Received: from google.com (176.13.105.34.bc.googleusercontent.com. [34.105.13.176]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b9cae55612sm4897165ad.73.2026.04.30.13.42.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2026 13:42:35 -0700 (PDT) Date: Thu, 30 Apr 2026 13:42:31 -0700 From: Vipin Sharma To: David Matlack Cc: iommu@lists.linux.dev, kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Adithya Jayachandran , Alexander Graf , Alex Williamson , Bjorn Helgaas , Chris Li , David Rientjes , Jacob Pan , Jason Gunthorpe , Joerg Roedel , Jonathan Corbet , Josh Hilke , Leon Romanovsky , Lukas Wunner , Mike Rapoport , Parav Pandit , Pasha Tatashin , Pranjal Shrivastava , Pratyush Yadav , Robin Murphy , Saeed Mahameed , Samiullah Khawaja , Shuah Khan , Will Deacon , William Tu , Yi Liu Subject: Re: [PATCH v4 02/11] PCI: liveupdate: Track outgoing preserved PCI devices Message-ID: <20260430204009.GB22297.vipinsh@google.com> References: <20260423212316.3431746-1-dmatlack@google.com> <20260423212316.3431746-3-dmatlack@google.com> <20260428201231.GA3885809.vipinsh@google.com> <20260430175916.GA13902.vipinsh@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260430_134237_554442_EF93B0E0 X-CRM114-Status: GOOD ( 25.12 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Thu, Apr 30, 2026 at 08:36:36PM +0000, David Matlack wrote: > On 2026-04-30 11:25 AM, Vipin Sharma wrote: > > On Tue, Apr 28, 2026 at 02:12:13PM -0700, David Matlack wrote: > > > On Tue, Apr 28, 2026 at 1:20 PM Vipin Sharma wrote: > > > > > > > > On Thu, Apr 23, 2026 at 09:23:06PM +0000, David Matlack wrote: > > > > > +int pci_liveupdate_preserve(struct pci_dev *dev) > > > > > +{ > > > > > > + if (ser->nr_devices == ser->max_nr_devices) > > > > > + return -ENOSPC; > > > > > + > > > > > + for (i = 0; i < ser->max_nr_devices; i++) { > > > > > + /* > > > > > + * Start searching at index ser->nr_devices. This should result > > > > > + * in a constant time search under expected conditions (devices > > > > > + * are not getting unpreserved). > > > > > + */ > > > > > + int index = (ser->nr_devices + i) % ser->max_nr_devices; > > > > > + struct pci_dev_ser *dev_ser = &ser->devices[index]; > > > > > + > > > > > + if (dev_ser->refcount) > > > > > + continue; > > > > > + > > > > > + pci_info(dev, "Device will be preserved across next Live Update\n"); > > > > > + ser->nr_devices++; > > > > > + > > > > > + dev_ser->domain = pci_domain_nr(dev->bus); > > > > > + dev_ser->bdf = pci_dev_id(dev); > > > > > + dev_ser->refcount = 1; > > > > > + > > > > > + dev->liveupdate_outgoing = dev_ser; > > > > > + return 0; > > > > > + } > > > > > + > > > > > + return -ENOSPC; > > > > > > > > Since it is executing under a mutex, and we already failed > > > > 'if (ser->nr_devices == ser->max_nr_devices) check above, will we ever reach > > > > here and return -ENOSPC? > > > > > > Yeah I wouldn't expect to ever reach here. > > > > Will you be removing it or want to keep it just in case scenario? > > I'm not sure how I would remove it. The code doesn't not compile without > a return. Oh, I meant, inside loop a break and outside just return 0, that way it won't be a dead code.