Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754077AbaGNJzE (ORCPT ); Mon, 14 Jul 2014 05:55:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31467 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751934AbaGNJy5 (ORCPT ); Mon, 14 Jul 2014 05:54:57 -0400 Date: Mon, 14 Jul 2014 11:55:39 +0200 From: Alexander Gordeev To: Yijing Wang Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 2/2] PCI/MSI: Remove arch_msi_check_device() Message-ID: <20140714095538.GA15981@dhcp-26-207.brq.redhat.com> References: <1005232855c3af2c0c669818ee63be445389b6ad.1405160163.git.agordeev@redhat.com> <53C33C6D.8020103@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53C33C6D.8020103@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 14, 2014 at 10:11:57AM +0800, Yijing Wang wrote: > > /** > > - * pci_msi_check_device - check whether MSI may be enabled on a device > > + * msi_check_device - check whether MSI may be enabled on a device > > * @dev: pointer to the pci_dev data structure of MSI device function > > * @nvec: how many MSIs have been requested ? > > - * @type: are we checking for MSI or MSI-X ? > > * > > * Look at global flags, the device itself, and its parent buses > > * to determine if MSI/-X are supported for the device. If MSI/-X is > > * supported return 0, else return an error code. > > **/ > > -static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) > > +static int msi_check_device(struct pci_dev *dev, int nvec) > > { > > struct pci_bus *bus; > > - int ret; > > > > /* MSI must be globally enabled and supported by the device */ > > - if (!pci_msi_enable || !dev || dev->no_msi) > > + if (!pci_msi_enable) > > + return -EINVAL; > > + > > + if (!dev || dev->no_msi || dev->current_state != PCI_D0) > > return -EINVAL; > > > > /* > > @@ -846,10 +837,6 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) > > if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI) > > return -EINVAL; > > > > - ret = arch_msi_check_device(dev, nvec, type); > > - if (ret) > > - return ret; > > - > > Move the arch_msi_check_device() into arch_msi_setup_irq(), make we can not detect whether the device in this platform > supports MSI or MSI-X aeap. If we delay this, maybe we will do a lot unnecessary working for MSI/MSI-X setup. A traditional approach for a function is first to make sanity check and then allocate resources. I do not see a reason to keep these two steps in separate functions: arch_msi_check_device() and arch_setup_msi_irq(). Just make checks within arch_setup_msi_irq() and bail out early would be as cheap as it is now, but more natural and would deflate the interface. Moreover, some platforms duplicate checks in arch_msi_check_device() and arch_setup_msi_irq(), which does not add to readability. > Thanks! > Yijing. > > > return 0; > > } > > > > @@ -954,13 +941,13 @@ int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec) > > int status, nr_entries; > > int i, j; > > > > - if (!entries || !dev->msix_cap || dev->current_state != PCI_D0) > > - return -EINVAL; > > - > > - status = pci_msi_check_device(dev, nvec, PCI_CAP_ID_MSIX); > > + status = msi_check_device(dev, nvec); > > if (status) > > return status; > > > > + if (!entries) > > + return -EINVAL; > > + > > nr_entries = pci_msix_vec_count(dev); > > if (nr_entries < 0) > > return nr_entries; > > @@ -1085,8 +1072,9 @@ int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec) > > int nvec; > > int rc; > > > > - if (dev->current_state != PCI_D0) > > - return -EINVAL; > > + rc = msi_check_device(dev, minvec); > > + if (rc) > > + return rc; > > > > WARN_ON(!!dev->msi_enabled); > > > > @@ -1109,17 +1097,6 @@ int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec) > > nvec = maxvec; > > > > do { > > - rc = pci_msi_check_device(dev, nvec, PCI_CAP_ID_MSI); > > - if (rc < 0) { > > - return rc; > > - } else if (rc > 0) { > > - if (rc < minvec) > > - return -ENOSPC; > > - nvec = rc; > > - } > > - } while (rc); > > - > > - do { > > rc = msi_capability_init(dev, nvec); > > if (rc < 0) { > > return rc; > > diff --git a/include/linux/msi.h b/include/linux/msi.h > > index 92a2f99..3b873bc 100644 > > --- a/include/linux/msi.h > > +++ b/include/linux/msi.h > > @@ -59,7 +59,6 @@ int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc); > > void arch_teardown_msi_irq(unsigned int irq); > > int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type); > > void arch_teardown_msi_irqs(struct pci_dev *dev); > > -int arch_msi_check_device(struct pci_dev* dev, int nvec, int type); > > void arch_restore_msi_irqs(struct pci_dev *dev); > > > > void default_teardown_msi_irqs(struct pci_dev *dev); > > @@ -76,8 +75,6 @@ struct msi_chip { > > int (*setup_irq)(struct msi_chip *chip, struct pci_dev *dev, > > struct msi_desc *desc); > > void (*teardown_irq)(struct msi_chip *chip, unsigned int irq); > > - int (*check_device)(struct msi_chip *chip, struct pci_dev *dev, > > - int nvec, int type); > > }; > > > > #endif /* LINUX_MSI_H */ > > > > > -- > Thanks! > Yijing > -- Regards, Alexander Gordeev agordeev@redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/