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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD61CC31E40 for ; Tue, 6 Aug 2019 18:48:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8651920818 for ; Tue, 6 Aug 2019 18:48:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725906AbfHFSss (ORCPT ); Tue, 6 Aug 2019 14:48:48 -0400 Received: from mga17.intel.com ([192.55.52.151]:55688 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725798AbfHFSsr (ORCPT ); Tue, 6 Aug 2019 14:48:47 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Aug 2019 11:48:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,353,1559545200"; d="scan'208";a="165069094" Received: from megha-z97x-ud7-th.sc.intel.com ([143.183.85.162]) by orsmga007.jf.intel.com with ESMTP; 06 Aug 2019 11:48:46 -0700 Message-ID: <1565118597.2401.116.camel@intel.com> Subject: Re: [RFC V1 RESEND 5/6] PCI/MSI: Free MSI-X resources by group From: Megha Dey To: Thomas Gleixner Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, marc.zyngier@arm.com, ashok.raj@intel.com, jacob.jun.pan@linux.intel.com, megha.dey@linux.intel.com Date: Tue, 06 Aug 2019 12:09:57 -0700 In-Reply-To: References: <1561162778-12669-1-git-send-email-megha.dey@linux.intel.com> <1561162778-12669-6-git-send-email-megha.dey@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.5.2-0ubuntu3.2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Sat, 2019-06-29 at 10:08 +0200, Thomas Gleixner wrote: > Megha, > > On Fri, 21 Jun 2019, Megha Dey wrote: > > > > +static int free_msi_irqs_grp(struct pci_dev *dev, int group_id) > > +{ > > > > + > > + for_each_pci_msi_entry(entry, dev) { > > + if (entry->group_id == group_id && entry->irq) > > + for (i = 0; i < entry->nvec_used; i++) > > + BUG_ON(irq_has_action(entry->irq + > > i)); > BUG_ON is wrong here. This can and must be handled gracefully. > Hmm, I reused this code from the 'free_msi_irqs' function. I am not sure why it is wrong to use BUG_ON here but ok to use it there, please let me know. > > > > + } > > + > > + pci_msi_teardown_msi_irqs_grp(dev, group_id); > > + > > + list_for_each_entry_safe(entry, tmp, msi_list, list) { > > + if (entry->group_id == group_id) { > > + clear_bit(entry->msi_attrib.entry_nr, dev- > > >entry); > > + list_del(&entry->list); > > + free_msi_entry(entry); > > + } > > + } > > + > > + list_for_each_entry_safe(msix_sysfs_entry, tmp_msix, > > pci_msix, list) { > > + if (msix_sysfs_entry->group_id == group_id) { > Again. Proper group management makes all of that just straight > forward and > not yet another special case. > Yeah, the new proposal of having a group_list would get rid of this. > > > > + msi_attrs = msix_sysfs_entry- > > >msi_irq_group->attrs; > >   > > +static void pci_msix_shutdown_grp(struct pci_dev *dev, int > > group_id) > > +{ > > + struct msi_desc *entry; > > + int grp_present = 0; > > + > > + if (pci_dev_is_disconnected(dev)) { > > + dev->msix_enabled = 0; > Huch? What's that? I can't figure out why this is needed and of > course it > completely lacks a comment explaining this.  > Again, I have reused this code from the pci_msix_shutdown() function. So for the group case, this is not required? > > > > + return; > > + } > > + > > + /* Return the device with MSI-X masked as initial states > > */ > > + for_each_pci_msi_entry(entry, dev) { > > + if (entry->group_id == group_id) { > > + /* Keep cached states to be restored */ > > + __pci_msix_desc_mask_irq(entry, 1); > > + grp_present = 1; > > + } > > + } > > + > > + if (!grp_present) { > > + pci_err(dev, "Group to be disabled not > > present\n"); > > + return; > So you print an error and silently return > This is a void function, hence no error value can be returned. What do you think is the right thing to do if someone wants to delete a group which is not present? > > > > + } > > +} > > + > > +int pci_disable_msix_grp(struct pci_dev *dev, int group_id) > > +{ > > + int num_vecs; > > + > > + if (!pci_msi_enable || !dev) > > + return -EINVAL; > > + > > + pci_msix_shutdown_grp(dev, group_id); > > + num_vecs = free_msi_irqs_grp(dev, group_id); > just to call in another function which has to do the same group_id > lookup > muck again. Even with the new proposal, we are to have 2 sets of functions: one to delete all the msic_desc entries associated with the device, and the other to delete those only belonging a 'user specified' group. So we do need to pass a group_id to these functions right? Yes, internally the deletion would be straightforward with the new approach. > > > > > + > > + return num_vecs; > > +} > > +EXPORT_SYMBOL(pci_disable_msix_grp); > Why is this exposed ? > As before, I just followed what pci_disable_msix() did . Looks like pci_disable_msix is called from a variety of drivers, thus it is exposed. Currently, no one will use the pci_disable_msix_grp() externally, thus it need not be exposed for now. > Thanks, > > tglx