Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755866AbZLSA1o (ORCPT ); Fri, 18 Dec 2009 19:27:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755699AbZLSA1j (ORCPT ); Fri, 18 Dec 2009 19:27:39 -0500 Received: from hera.kernel.org ([140.211.167.34]:36883 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755657AbZLSA1b (ORCPT ); Fri, 18 Dec 2009 19:27:31 -0500 Message-ID: <4B2C1DA9.4030907@kernel.org> Date: Fri, 18 Dec 2009 16:26:17 -0800 From: Yinghai Lu User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Linus Torvalds CC: Jesse Barnes , Ingo Molnar , Ivan Kokshaysky , Kenji Kaneshige , Alex Chiang , Bjorn Helgaas , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" Subject: Re: [PATCH 2/12] pci: add pci_bridge_release_unused_res and pci_bus_release_unused_bridge_res -v2 References: <4B2BE9DD.3040504@kernel.org> <4B2BEC1B.9090104@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7532 Lines: 260 Linus Torvalds wrote: > > On Fri, 18 Dec 2009, Yinghai Lu wrote: >> so later we could use it to release small resource before pci assign unassign res > > However, I think this one is wrong. > >> +static void release_child_resources(struct resource *r) >> +{ >> + struct resource *p; >> + resource_size_t size; >> + >> + p = r->child; >> + while (p) { >> + release_child_resources(p); >> + release_resource(p); > > So not only is this releasing resources that aren't necessarily PCI > devices, it's releasing the whole tree - regardless of how they were > allocated and initialized. That makes me nervous to begin with. It's in > the wrong file. > > But the locking is crap too! > > You need to hold the resource lock for the whole operation - you can't > just walk the resource tree and release them. > > And once you do that, then using "release_resrouce()" is the wrong thing, > since it turns into just "__release_resource()" and you notice that that > walks the chain looking for them - which makes it pointless to have > _another_ outer loop that walks the chain to release them! > > So you'd need to > > - move this to kernel/resource.c > > - do it all under 'write_lock(&resource_lock);' > > - stop the silly double list loop, and just do it as a single loop that > does > > p = old->parent->child; > old->parent = NULL; > while (p) { > struct resource *tmp = p; > p = p->sibling; > > .. do whatever you do to free tmp .. > } > > and it's much simpler, more efficient, has the rigth locking, and is in > the right place. ok, please check attached is right or not > > That said, it's still unclear if you can ever do this! Why would the PCI > layer be allowed to release ACPI resources int he tree, for example? > > So I can see fixing the _implementation_ issues I have like above, but I'd > still be nervous about the whole concept of the patch.. those code are only called during early stage when pci_assign unassigned, and pcie hotplug under the pcie port. also that is the pci_try_num is default to 1, and only be changed by pci=try=2 etc. only second try start to call those functions. Thanks Yinghai Subject: [PATCH 2/12] pci: add pci_bridge_release_unused_res and pci_bus_release_unused_bridge_res -v3 so later we could use it to release small resource before pci assign unassign res -v2: change name to release_child_resources according to Jesse -v3: according to Linus, move release_child_resources to resource.c also need to put the lock around them all to avoid recursive deep. (my test case only have one level that need to be released) Signed-off-by: Yinghai Lu --- drivers/pci/setup-bus.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++- include/linux/ioport.h | 1 kernel/resource.c | 30 +++++++++++++++ 3 files changed, 125 insertions(+), 1 deletion(-) Index: linux-2.6/drivers/pci/setup-bus.c =================================================================== --- linux-2.6.orig/drivers/pci/setup-bus.c +++ linux-2.6/drivers/pci/setup-bus.c @@ -209,7 +209,6 @@ static void pci_setup_bridge_mmio_pref(s l = (region.start >> 16) & 0xfff0; l |= region.end & 0xfff00000; if (res->flags & IORESOURCE_MEM_64) { - pref_mem64 = 1; bu = upper_32_bits(region.start); lu = upper_32_bits(region.end); } @@ -608,6 +607,100 @@ void __ref pci_bus_assign_resources(cons } EXPORT_SYMBOL(pci_bus_assign_resources); +static void pci_bridge_release_unused_res(struct pci_bus *bus, + unsigned long type) +{ + int idx; + bool changed = false; + struct pci_dev *dev; + struct resource *r; + unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM | + IORESOURCE_PREFETCH; + + /* for pci bridges res only */ + dev = bus->self; + for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_BRIDGE_RESOURCES + 3; + idx++) { + r = &dev->resource[idx]; + if ((r->flags & type_mask) != type) + continue; + if (!r->parent) + continue; + /* + * if there are children under that, we should release them + * all + */ + release_child_resources(r); + if (!release_resource(r)) { + dev_printk(KERN_DEBUG, &dev->dev, + "resource %d %pR released\n", idx, r); + /* keep the old size */ + r->end = resource_size(r) - 1; + r->start = 0; + r->flags = 0; + changed = true; + } + } + + if (changed) { + if (type & IORESOURCE_PREFETCH) { + /* avoiding touch the one without PREF */ + type = IORESOURCE_PREFETCH; + } + __pci_setup_bridge(bus, type); + } +} + +/* + * try to release pci bridge resources that is from leaf bridge, + * so we can allocate big new one later + * check: + * 0: only release the bridge and only the bridge is leaf + * 1: release all down side bridge for third shoot + */ +static void __ref pci_bus_release_unused_bridge_res(struct pci_bus *bus, + unsigned long type, + int check_leaf) +{ + struct pci_dev *dev; + bool is_leaf_bridge = true; + + list_for_each_entry(dev, &bus->devices, bus_list) { + struct pci_bus *b = dev->subordinate; + if (!b) + continue; + + switch (dev->class >> 8) { + case PCI_CLASS_BRIDGE_CARDBUS: + is_leaf_bridge = false; + break; + + case PCI_CLASS_BRIDGE_PCI: + default: + is_leaf_bridge = false; + if (!check_leaf) + pci_bus_release_unused_bridge_res(b, type, + check_leaf); + break; + } + } + + /* The root bus? */ + if (!bus->self) + return; + + switch (bus->self->class >> 8) { + case PCI_CLASS_BRIDGE_CARDBUS: + break; + + case PCI_CLASS_BRIDGE_PCI: + default: + if ((check_leaf && is_leaf_bridge) || !check_leaf) + pci_bridge_release_unused_res(bus, type); + break; + } +} + static void pci_bus_dump_res(struct pci_bus *bus) { int i; Index: linux-2.6/include/linux/ioport.h =================================================================== --- linux-2.6.orig/include/linux/ioport.h +++ linux-2.6/include/linux/ioport.h @@ -112,6 +112,7 @@ extern struct resource iomem_resource; extern int request_resource(struct resource *root, struct resource *new); extern int release_resource(struct resource *new); +void release_child_resources(struct resource *new); extern void reserve_region_with_split(struct resource *root, resource_size_t start, resource_size_t end, const char *name); Index: linux-2.6/kernel/resource.c =================================================================== --- linux-2.6.orig/kernel/resource.c +++ linux-2.6/kernel/resource.c @@ -188,6 +188,36 @@ static int __release_resource(struct res return -EINVAL; } +static void __release_child_resources(struct resource *r) +{ + struct resource *tmp, *p; + resource_size_t size; + + p = r->child; + r->child = NULL; + while (p) { + tmp = p; + p = p->sibling; + + tmp->parent = NULL; + tmp->sibling = NULL; + __release_child_resources(tmp); + + printk(KERN_DEBUG "release child resource %pR\n", tmp); + /* need to restore size, and keep flags */ + size = resource_size(tmp); + tmp->start = 0; + tmp->end = size - 1; + } +} + +void release_child_resources(struct resource *r) +{ + write_lock(&resource_lock); + __release_child_resources(r); + write_unlock(&resource_lock); +} + /** * request_resource - request and reserve an I/O or memory resource * @root: root resource descriptor -- 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/