From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752171AbcIWECb (ORCPT ); Fri, 23 Sep 2016 00:02:31 -0400 Received: from mx2.suse.de ([195.135.220.15]:37487 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750720AbcIWEC3 (ORCPT ); Fri, 23 Sep 2016 00:02:29 -0400 Subject: Re: [PATCH v3 2/3] xen/pciback: avoid multiple entries in slot list To: Boris Ostrovsky , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org References: <1474533941-6976-1-git-send-email-jgross@suse.com> <1474533941-6976-3-git-send-email-jgross@suse.com> Cc: david.vrabel@citrix.com From: Juergen Gross Message-ID: Date: Fri, 23 Sep 2016 06:02:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/09/16 23:02, Boris Ostrovsky wrote: > On 09/22/2016 04:45 AM, Juergen Gross wrote: >> The Xen pciback driver has a list of all pci devices it is ready to >> seize. There is no check whether a to be added entry already exists. >> While this might be no problem in the common case it might confuse >> those which consume the list via sysfs. >> >> Modify the handling of this list by not adding an entry which already >> exists. As this will be needed later split out the list handling into >> a separate function. >> >> Signed-off-by: Juergen Gross >> --- >> drivers/xen/xen-pciback/pci_stub.c | 39 ++++++++++++++++++++++++++++++-------- >> 1 file changed, 31 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c >> index 79a9e4d..0179333 100644 >> --- a/drivers/xen/xen-pciback/pci_stub.c >> +++ b/drivers/xen/xen-pciback/pci_stub.c >> @@ -478,6 +478,36 @@ static int __init pcistub_init_devices_late(void) >> return 0; >> } >> >> +static void pcistub_device_id_add_list(struct pcistub_device_id *new, >> + int domain, int bus, unsigned int devfn) >> +{ >> + struct pcistub_device_id *pci_dev_id; >> + unsigned long flags; >> + int found = 0; >> + >> + spin_lock_irqsave(&device_ids_lock, flags); >> + >> + list_for_each_entry(pci_dev_id, &pcistub_device_ids, slot_list) { >> + if (pci_dev_id->domain == domain && pci_dev_id->bus == bus && >> + pci_dev_id->devfn == devfn) { >> + found = 1; >> + break; >> + } >> + } >> + >> + if (!found) { >> + new->domain = domain; >> + new->bus = bus; >> + new->devfn = devfn; >> + list_add_tail(&new->slot_list, &pcistub_device_ids); >> + } >> + >> + spin_unlock_irqrestore(&device_ids_lock, flags); >> + >> + if (found) >> + kfree(new); > > I'd rather free 'new' in the caller (who allocated it) and return > something like -EEXIST if device is already on the list. Hmm, I thought of this, but with two callers after the following patch having to deal with the situation I've chosen this way to do it. The code is smaller this way. Juergen