From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751896AbcFWLQR (ORCPT ); Thu, 23 Jun 2016 07:16:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42031 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751589AbcFWLQP (ORCPT ); Thu, 23 Jun 2016 07:16:15 -0400 Date: Thu, 23 Jun 2016 13:16:10 +0200 From: Alexander Gordeev To: Christoph Hellwig Cc: tglx@linutronix.de, axboe@fb.com, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free routines Message-ID: <20160623111610.GA28861@dhcp-27-118.brq.redhat.com> References: <1465934346-20648-1-git-send-email-hch@lst.de> <1465934346-20648-8-git-send-email-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1465934346-20648-8-git-send-email-hch@lst.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 23 Jun 2016 11:16:15 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 14, 2016 at 09:59:00PM +0200, Christoph Hellwig wrote: > Add a helper to allocate a range of interrupt vectors, which will > transparently use MSI-X and MSI if available or fallback to legacy > vectors. The interrupts are available in a core managed array > in the pci_dev structure, and can also be released using a similar > helper. > > The next patch will also add automatic spreading of MSI / MSI-X > vectors to this function. > > Signed-off-by: Christoph Hellwig > --- > drivers/pci/msi.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/pci.h | 18 +++++++++ New APIs should be documented in Documentation/PCI/MSI-HOWTO.txt, I guess. > 2 files changed, 128 insertions(+) > > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > index a080f44..a33adec 100644 > --- a/drivers/pci/msi.c > +++ b/drivers/pci/msi.c > @@ -4,6 +4,7 @@ > * > * Copyright (C) 2003-2004 Intel > * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com) > + * Copyright (c) 2016 Christoph Hellwig. > */ > > #include > @@ -1120,6 +1121,115 @@ int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries, > } > EXPORT_SYMBOL(pci_enable_msix_range); > > +static unsigned int pci_nr_irq_vectors(struct pci_dev *pdev) > +{ > + int nr_entries; > + > + nr_entries = pci_msix_vec_count(pdev); > + if (nr_entries <= 0 && pci_msi_supported(pdev, 1)) > + nr_entries = pci_msi_vec_count(pdev); > + if (nr_entries <= 0) > + nr_entries = 1; > + return nr_entries; > +} This function is strange, because it: (a) does not consider PCI_IRQ_NOMSIX flag; (b) only calls pci_msi_supported() for MSI case; (c) calls pci_msi_supported() with just one vector; (d) might return suboptimal number of vectors (number of MSI-X used later for MSI or vice versa) Overall, I would suggest simply return maximum between MSI-X and MSI numbers and let the rest of the code (i.e the two range functions) handle a-d. > +static int pci_enable_msix_range_wrapper(struct pci_dev *pdev, u32 *irqs, > + unsigned int min_vecs, unsigned int max_vecs) > +{ > + struct msix_entry *msix_entries; > + int vecs, i; > + > + msix_entries = kcalloc(max_vecs, sizeof(struct msix_entry), GFP_KERNEL); > + if (!msix_entries) > + return -ENOMEM; > + > + for (i = 0; i < max_vecs; i++) > + msix_entries[i].entry = i; > + > + vecs = pci_enable_msix_range(pdev, msix_entries, min_vecs, max_vecs); > + if (vecs > 0) { This condition check is unneeded. > + for (i = 0; i < vecs; i++) > + irqs[i] = msix_entries[i].vector; > + } > + > + kfree(msix_entries); > + return vecs; > +} > + > +/** > + * pci_alloc_irq_vectors - allocate multiple IRQs for a device > + * @dev: PCI device to operate on > + * @min_vecs: minimum number of vectors required (must be >= 1) > + * @max_vecs: maximum (desired) number of vectors > + * @flags: flags or quirks for the allocation > + * > + * Allocate up to @max_vecs interrupt vectors for @dev, using MSI-X or MSI > + * vectors if available, and fall back to a single legacy vector > + * if neither is available. Return the number of vectors allocated, > + * (which might be smaller than @max_vecs) if successful, or a negative > + * error code on error. The Linux irq numbers for the allocated > + * vectors are stored in pdev->irqs. If less than @min_vecs interrupt > + * vectors are available for @dev the function will fail with -ENOSPC. > + */ > +int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs, > + unsigned int max_vecs, unsigned int flags) > +{ > + unsigned int vecs, i; > + u32 *irqs; > + > + max_vecs = min(max_vecs, pci_nr_irq_vectors(dev)); Optionally, you could move this assignment to pci_nr_irq_vectors() and simply let it handle number of vectors to request. > + irqs = kcalloc(max_vecs, sizeof(u32), GFP_KERNEL); > + if (!irqs) > + return -ENOMEM; > + > + if (!(flags & PCI_IRQ_NOMSIX)) { > + vecs = pci_enable_msix_range_wrapper(dev, irqs, min_vecs, > + max_vecs); > + if (vecs > 0) > + goto done; > + } > + > + vecs = pci_enable_msi_range(dev, min_vecs, max_vecs); > + if (vecs > 0) { > + for (i = 0; i < vecs; i++) > + irqs[i] = dev->irq + i; > + goto done; > + } > + > + if (min_vecs > 1) > + return -ENOSPC; irqs is leaked if (min_vecs > 1) You can get rid of this check at all if you reorganize your code i.e. like this: ... vecs = pci_enable_msi_range(dev, min_vecs, max_vecs); if (vecs < 0) goto legacy; for (i = 0; i < vecs; i++) irqs[i] = dev->irq + i; done: ... legacy: ... > + > + /* use legacy irq */ > + kfree(irqs); > + dev->irqs = &dev->irq; > + return 1; > + > +done: > + dev->irqs = irqs; > + return vecs; > +} > +EXPORT_SYMBOL(pci_alloc_irq_vectors); > + > +/** > + * pci_free_irq_vectors - free previously allocated IRQs for a device > + * @dev: PCI device to operate on > + * > + * Undoes the allocations and enabling in pci_alloc_irq_vectors(). > + */ > +void pci_free_irq_vectors(struct pci_dev *dev) > +{ > + if (dev->msix_enabled) > + pci_disable_msix(dev); > + else if (dev->msi_enabled) > + pci_disable_msi(dev); The checks are probably redundant or incomplete. Redundant - because pci_disable_msi()/pci_disable_msix() do it anyways: if (!pci_msi_enable || !dev || !dev->msi_enabled) return; Incomplete - because the two other conditions are not checked. > + if (dev->irqs != &dev->irq) > + kfree(dev->irqs); Unset dev->irqs? BTW, since (dev->irqs == &dev->irq) effectively checks if MSI/MSI-X was enabled this function could bail out in case they did not. > +} > +EXPORT_SYMBOL(pci_free_irq_vectors); > + > + > struct pci_dev *msi_desc_to_pci_dev(struct msi_desc *desc) > { > return to_pci_dev(desc->dev); > diff --git a/include/linux/pci.h b/include/linux/pci.h > index b67e4df..84a20fc 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -320,6 +320,7 @@ struct pci_dev { > * directly, use the values stored here. They might be different! > */ > unsigned int irq; > + unsigned int *irqs; > struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */ > > bool match_driver; /* Skip attaching driver */ > @@ -1237,6 +1238,8 @@ resource_size_t pcibios_iov_resource_alignment(struct pci_dev *dev, int resno); > int pci_set_vga_state(struct pci_dev *pdev, bool decode, > unsigned int command_bits, u32 flags); > > +#define PCI_IRQ_NOMSIX (1 << 0) /* don't try to use MSI-X interrupts */ BTW, why PCI_IRQ_NOMSIX only and no PCI_IRQ_NOMSI? > /* kmem_cache style wrapper around pci_alloc_consistent() */ > > #include > @@ -1284,6 +1287,9 @@ static inline int pci_enable_msix_exact(struct pci_dev *dev, > return rc; > return 0; > } > +int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs, > + unsigned int max_vecs, unsigned int flags); > +void pci_free_irq_vectors(struct pci_dev *dev); > #else > static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; } > static inline void pci_msi_shutdown(struct pci_dev *dev) { } > @@ -1307,6 +1313,18 @@ static inline int pci_enable_msix_range(struct pci_dev *dev, > static inline int pci_enable_msix_exact(struct pci_dev *dev, > struct msix_entry *entries, int nvec) > { return -ENOSYS; } > +static inline int pci_alloc_irq_vectors(struct pci_dev *dev, > + unsigned int min_vecs, unsigned int max_vecs, > + unsigned int flags) > +{ > + if (min_vecs > 1) > + return -ENOSPC; > + dev->irqs = &dev->irq; > + return 1; > +} > +static inline void pci_free_irq_vectors(struct pci_dev *dev) > +{ Unset dev->irqs? > +} > #endif > > #ifdef CONFIG_PCIEPORTBUS > -- > 2.1.4 >