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Message-Id: <201101181352.08013.bjorn.helgaas@hp.com>
Date: Tue, 18 Jan 2011 13:52:06 -0700
From: Bjorn Helgaas <bjorn.helgaas@...com>
To: Ram Pai <linuxram@...ibm.com>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org, clemens@...isch.de,
Yinghai Lu <yinghai@...nel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
peter.henriksson@...il.com, ebiederm@...stanetworks.com
Subject: Re: [PATCH 1/1] PCI: allocate essential resources before reserving hotplug resources
On Friday, January 14, 2011 11:19:15 am Ram Pai wrote:
> PCI: reserve additional resources for hotplug bridges
> only after all essential resources are allocated.
>
> Linux tries to reserve minimal resources for hotplug
> bridges. This works fine as long as there are enough
> resources to satisfy all other essential resource
> requirements. However if enough resources are not
> available to satisfy both the essential resources
> and the reservation for hotplug resources, the
> resource-allocator reports error and returns failure.
>
> This patch distinguishes between essential resources and
> nice-to-have resources. Any failure to allocate
> nice-to-have resources are ignored.
>
> This behavior can be particularly useful to trigger
> automatic reallocation, if the OS discovers genuine
> resource allocation conflicts or genuine unallocated
> requests caused by not-so-smart allocation behavior of
> the native BIOS.
>
> https://bugzilla.kernel.org/show_bug.cgi?id=15960
> captures the details of the issue and the motivation
> behind this patch.
Please don't indent and right-justify the changelog.
This is a PCI-specific issue, so I'm not comfortable adding add_size
to struct resource. That penalizes all resource users while only
helping PCI. Also, the struct resource lives forever, and the
add_size information is only useful while we're configuring the
bridge.
Bjorn
> Signed-off-by: Ram Pai <linuxram@...ibm.com>
>
> drivers/pci/setup-bus.c | 142 +++++++++++++++++++++++++++++++++++-------------
> include/linux/ioport.h | 1
> 2 files changed, 105 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 66cb8f4..76a7fb7 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -91,7 +91,26 @@ static void __dev_sort_resources(struct pci_dev *dev,
> pdev_sort_resources(dev, head);
> }
>
> -static void __assign_resources_sorted(struct resource_list *head,
> +
> +static void adjust_resources_sorted(struct resource_list *head)
> +{
> + struct resource *res;
> + struct resource_list *list, *tmp;
> + int idx;
> +
> + for (list = head->next; list;) {
> + res = list->res;
> + idx = res - &list->dev->resource[0];
> + if (res->add_size)
> + adjust_resource(res, res->start,
> + resource_size(res) + res->add_size);
> + tmp = list;
> + list = list->next;
> + kfree(tmp);
> + }
> +}
> +
> +static void assign_requested_resources_sorted(struct resource_list *head,
> struct resource_list_x *fail_head)
> {
> struct resource *res;
> @@ -114,14 +133,25 @@ static void __assign_resources_sorted(struct resource_list *head,
> }
> res->start = 0;
> res->end = 0;
> + res->add_size = 0;
> res->flags = 0;
> }
> tmp = list;
> list = list->next;
> - kfree(tmp);
> }
> }
>
> +static void __assign_resources_sorted(struct resource_list *head,
> + struct resource_list_x *fail_head)
> +{
> + /* Satisfy the must-have resource requests */
> + assign_requested_resources_sorted(head, fail_head);
> +
> + /* Try to satisfy any additional nice-to-have resource
> + requests */
> + adjust_resources_sorted(head);
> +}
> +
> static void pdev_assign_resources_sorted(struct pci_dev *dev,
> struct resource_list_x *fail_head)
> {
> @@ -404,15 +434,37 @@ static struct resource *find_free_bus_resource(struct pci_bus *bus, unsigned lon
> return NULL;
> }
>
> +static resource_size_t calculate_iosize(resource_size_t size,
> + resource_size_t min_size,
> + resource_size_t size1,
> + resource_size_t old_size,
> + resource_size_t align)
> +{
> + if (size < min_size)
> + size = min_size;
> + if (old_size == 1 )
> + old_size = 0;
> + /* To be fixed in 2.5: we should have sort of HAVE_ISA
> + flag in the struct pci_bus. */
> +#if defined(CONFIG_ISA) || defined(CONFIG_EISA)
> + size = (size & 0xff) + ((size & ~0xffUL) << 2);
> +#endif
> + size = ALIGN(size + size1, align);
> + if (size < old_size)
> + size = old_size;
> + return size;
> +}
> +
> /* Sizing the IO windows of the PCI-PCI bridge is trivial,
> since these windows have 4K granularity and the IO ranges
> of non-bridge PCI devices are limited to 256 bytes.
> We must be careful with the ISA aliasing though. */
> -static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size)
> +static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
> + resource_size_t add_size)
> {
> struct pci_dev *dev;
> struct resource *b_res = find_free_bus_resource(bus, IORESOURCE_IO);
> - unsigned long size = 0, size1 = 0, old_size;
> + unsigned long size = 0, size1 = 0;
>
> if (!b_res)
> return;
> @@ -435,20 +487,16 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size)
> size1 += r_size;
> }
> }
> - if (size < min_size)
> - size = min_size;
> - old_size = resource_size(b_res);
> - if (old_size == 1)
> - old_size = 0;
> -/* To be fixed in 2.5: we should have sort of HAVE_ISA
> - flag in the struct pci_bus. */
> -#if defined(CONFIG_ISA) || defined(CONFIG_EISA)
> - size = (size & 0xff) + ((size & ~0xffUL) << 2);
> -#endif
> - size = ALIGN(size + size1, 4096);
> - if (size < old_size)
> - size = old_size;
> - if (!size) {
> +
> + size = calculate_iosize(size, min_size, size1,
> + resource_size(b_res), 4096);
> + if (add_size)
> + size1 = calculate_iosize(size, min_size+add_size, size1,
> + resource_size(b_res), 4096);
> + else
> + size1 = size;
> +
> + if (!size && !size1) {
> if (b_res->start || b_res->end)
> dev_info(&bus->self->dev, "disabling bridge window "
> "%pR to [bus %02x-%02x] (unused)\n", b_res,
> @@ -459,16 +507,35 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size)
> /* Alignment of the IO window is always 4K */
> b_res->start = 4096;
> b_res->end = b_res->start + size - 1;
> + b_res->add_size = size1-size;
> b_res->flags |= IORESOURCE_STARTALIGN;
> }
>
> +
> +static resource_size_t calculate_memsize(resource_size_t size,
> + resource_size_t min_size,
> + resource_size_t size1,
> + resource_size_t old_size,
> + resource_size_t align)
> +{
> + if (size < min_size)
> + size = min_size;
> + if (old_size == 1 )
> + old_size = 0;
> + if (size < old_size)
> + size = old_size;
> + size = ALIGN(size + size1, align);
> + return size;
> +}
> +
> /* Calculate the size of the bus and minimal alignment which
> guarantees that all child resources fit in this size. */
> static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
> - unsigned long type, resource_size_t min_size)
> + unsigned long type, resource_size_t min_size,
> + resource_size_t add_size)
> {
> struct pci_dev *dev;
> - resource_size_t min_align, align, size, old_size;
> + resource_size_t min_align, align, size, size1;
> resource_size_t aligns[12]; /* Alignments from 1Mb to 2Gb */
> int order, max_order;
> struct resource *b_res = find_free_bus_resource(bus, type);
> @@ -516,13 +583,6 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
> mem64_mask &= r->flags & IORESOURCE_MEM_64;
> }
> }
> - if (size < min_size)
> - size = min_size;
> - old_size = resource_size(b_res);
> - if (old_size == 1)
> - old_size = 0;
> - if (size < old_size)
> - size = old_size;
>
> align = 0;
> min_align = 0;
> @@ -537,8 +597,14 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
> min_align = align1 >> 1;
> align += aligns[order];
> }
> - size = ALIGN(size, min_align);
> - if (!size) {
> +
> + size = calculate_memsize(size, min_size, 0, resource_size(b_res), align);
> + if (add_size)
> + size1 = calculate_memsize(size, min_size+add_size, 0, resource_size(b_res), align);
> + else
> + size1 = size;
> +
> + if (!size && !size1) {
> if (b_res->start || b_res->end)
> dev_info(&bus->self->dev, "disabling bridge window "
> "%pR to [bus %02x-%02x] (unused)\n", b_res,
> @@ -548,8 +614,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
> }
> b_res->start = min_align;
> b_res->end = size + min_align - 1;
> - b_res->flags |= IORESOURCE_STARTALIGN;
> - b_res->flags |= mem64_mask;
> + b_res->add_size = size1 - size;
> + b_res->flags |= IORESOURCE_STARTALIGN | mem64_mask;
> return 1;
> }
>
> @@ -606,7 +672,7 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
> {
> struct pci_dev *dev;
> unsigned long mask, prefmask;
> - resource_size_t min_mem_size = 0, min_io_size = 0;
> + resource_size_t additional_mem_size = 0, additional_io_size = 0;
>
> list_for_each_entry(dev, &bus->devices, bus_list) {
> struct pci_bus *b = dev->subordinate;
> @@ -637,11 +703,11 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
> case PCI_CLASS_BRIDGE_PCI:
> pci_bridge_check_ranges(bus);
> if (bus->self->is_hotplug_bridge) {
> - min_io_size = pci_hotplug_io_size;
> - min_mem_size = pci_hotplug_mem_size;
> + additional_io_size = pci_hotplug_io_size;
> + additional_mem_size = pci_hotplug_mem_size;
> }
> default:
> - pbus_size_io(bus, min_io_size);
> + pbus_size_io(bus, 0, additional_io_size);
> /* If the bridge supports prefetchable range, size it
> separately. If it doesn't, or its prefetchable window
> has already been allocated by arch code, try
> @@ -649,11 +715,11 @@ void __ref pci_bus_size_bridges(struct pci_bus *bus)
> resources. */
> mask = IORESOURCE_MEM;
> prefmask = IORESOURCE_MEM | IORESOURCE_PREFETCH;
> - if (pbus_size_mem(bus, prefmask, prefmask, min_mem_size))
> + if (pbus_size_mem(bus, prefmask, prefmask, 0, additional_mem_size))
> mask = prefmask; /* Success, size non-prefetch only. */
> else
> - min_mem_size += min_mem_size;
> - pbus_size_mem(bus, mask, IORESOURCE_MEM, min_mem_size);
> + additional_mem_size += additional_mem_size;
> + pbus_size_mem(bus, mask, IORESOURCE_MEM, 0, additional_mem_size);
> break;
> }
> }
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index e9bb22c..d00c61c 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -18,6 +18,7 @@
> struct resource {
> resource_size_t start;
> resource_size_t end;
> + resource_size_t add_size;
> const char *name;
> unsigned long flags;
> struct resource *parent, *sibling, *child;
>
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