Messages in this thread | | | Subject | Re: [RFC PATCH v4 1/7] PCI: Add a new option for resource_alignment to reassign alignment | From | Alexey Kardashevskiy <> | Date | Thu, 10 Mar 2016 13:19:39 +1100 |
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On 03/07/2016 06:48 PM, Yongji Xie wrote: > When using resource_alignment kernel parameter, the current > implement reassigns the alignment by changing resources' size > which can potentially break some drivers.
How can this possibly break any driver?... It rounds up, not down, what do I miss here?
> > So this patch adds a new option "noresize" for the parameter > to solve this problem. > > Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com> > --- > Documentation/kernel-parameters.txt | 5 ++++- > drivers/pci/pci.c | 36 +++++++++++++++++++++++++---------- > 2 files changed, 30 insertions(+), 11 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 9a53c92..d8b29ab 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2912,13 +2912,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > window. The default value is 64 megabytes. > resource_alignment= > Format: > - [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] > + [<order of align>@][<domain>:]<bus>:<slot>.<func> > + [:noresize][; ...] > Specifies alignment and device to reassign > aligned memory resources. > If <order of align> is not specified, > PAGE_SIZE is used as alignment. > PCI-PCI bridge can be specified, if resource > windows need to be expanded. > + noresize: Don't change the resources' sizes when > + reassigning alignment. > ecrc= Enable/disable PCIe ECRC (transaction layer > end-to-end CRC checking). > bios: Use BIOS/firmware settings. This is the > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 602eb42..760cce5 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -4598,7 +4598,8 @@ static DEFINE_SPINLOCK(resource_alignment_lock); > * RETURNS: Resource alignment if it is specified. > * Zero if it is not specified. > */ > -static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev) > +static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev, > + bool *resize) > { > int seg, bus, slot, func, align_order, count; > resource_size_t align = 0; > @@ -4626,6 +4627,11 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev) > } > } > p += count; > + if (!strncmp(p, ":noresize", 9)) { > + *resize = false; > + p += 9; > + } else > + *resize = true; > if (seg == pci_domain_nr(dev->bus) && > bus == dev->bus->number && > slot == PCI_SLOT(dev->devfn) && > @@ -4658,11 +4664,12 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) > { > int i; > struct resource *r; > + bool resize; > resource_size_t align, size; > u16 command; > > /* check if specified PCI is target device to reassign */ > - align = pci_specified_resource_alignment(dev); > + align = pci_specified_resource_alignment(dev, &resize);
A compiler should have warned here about passing a pointer to unitialized @resize.
> if (!align) > return; > > @@ -4684,15 +4691,24 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) > if (!(r->flags & IORESOURCE_MEM)) > continue; > size = resource_size(r); > - if (size < align) { > - size = align; > - dev_info(&dev->dev, > - "Rounding up size of resource #%d to %#llx.\n", > - i, (unsigned long long)size); > + if (resize) { > + if (size < align) { > + size = align; > + dev_info(&dev->dev, > + "Rounding up size of resource #%d to %#llx.\n", > + i, (unsigned long long)size); > + } > + r->flags |= IORESOURCE_UNSET; > + r->end = size - 1; > + r->start = 0; > + } else { > + if (size > align) > + align = size; > + r->flags &= ~IORESOURCE_SIZEALIGN; > + r->flags |= IORESOURCE_STARTALIGN | IORESOURCE_UNSET; > + r->start = align; > + r->end = r->start + size - 1; > } > - r->flags |= IORESOURCE_UNSET; > - r->end = size - 1; > - r->start = 0; > } > /* Need to disable bridge's resource window, > * to enable the kernel to reassign new resource >
-- Alexey
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