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Date: Thu, 18 May 2017 13:27:05 +0800
From: jeffy <jeffy.chen@...k-chips.com>
To: Bjorn Helgaas <helgaas@...nel.org>
CC: linux-pci@...r.kernel.org, robh@...nel.org, toshi.kani@....com,
shawn.lin@...k-chips.com, briannorris@...omium.org,
linux-kernel@...r.kernel.org, dianders@...omium.org,
bhelgaas@...gle.com, dtor@...omium.org, devicetree@...r.kernel.org,
Rob Herring <robh+dt@...nel.org>,
Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH v5] of/pci: Fix memory leak in of_pci_get_host_bridge_resources
Hi Bjorn,
On 05/18/2017 05:08 AM, Bjorn Helgaas wrote:
> On Wed, Apr 05, 2017 at 10:28:22AM +0800, Jeffy Chen wrote:
>> Currently we only free the allocated resource struct when error.
>> This would cause memory leak after pci_free_resource_list.
>
> I think I see the problem here. The release path is this:
>
> pci_release_host_bridge_dev
> pci_free_resource_list
> resource_list_free
> list_for_each_entry_safe(entry, tmp, head, node)
> resource_list_destroy_entry
> resource_list_del
> resource_list_free_entry
> kfree(entry)
>
> but that frees only the struct resource_entry, not the struct resource
> pointed to by entry->res. Is that right?
right, that's the leak.
>
> And this patch solves it for of_pci_get_host_bridge_resources() by
> always making entry->res point to entry->__res, which is an element in
> struct resource_entry, so it's sufficient to free the resource_entry.
>
> The memory management here is pretty tangled. I wonder if there's
> some way to simplify it so it's easier to make sure everybody does it
> correctly. For example, could we remove the entry->res pointer
> completely and force everybody to use entry->__res?
i've tried something like this in
https://patchwork.kernel.org/patch/9638003/
but it turns out there are a few codes trying to use shared
resources(entry->res pointer point to some common resources), for example:
./arch/tile/kernel/pci.c:307:
pci_add_resource(&resources, &ioport_resource);
./arch/tile/kernel/pci.c:308:
pci_add_resource(&resources, &iomem_resource);
so i tried to use IORESOURCE_AUTO to handle non-common(private) resources.
and i saw drivers/pnp/manager.c tried to handle something like this too,
by manually free resources marked as IORESOURCE_AUTO:
static void pnp_clean_resource_table(struct pnp_dev *dev)
{
struct pnp_resource *pnp_res, *tmp;
list_for_each_entry_safe(pnp_res, tmp, &dev->resources, list) {
if (pnp_res->res.flags & IORESOURCE_AUTO)
pnp_free_resource(pnp_res);
}
}
>
>> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
>> ---
>>
>> Changes in v5:
>> Fix some careless compile errors.
>>
>> Changes in v4:
>> Use IORESOURCE_AUTO to mark struct resources which could be copied.
>>
>> Changes in v3:
>> Add some comments.
>>
>> Changes in v2:
>> Don't change the resource_list_create_entry's behavior.
>>
>> drivers/of/of_pci.c | 51 ++++++++++++++++++---------------------------------
>> drivers/pci/bus.c | 7 ++++++-
>> 2 files changed, 24 insertions(+), 34 deletions(-)
>>
>> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
>> index 0ee42c3..49233bf 100644
>> --- a/drivers/of/of_pci.c
>> +++ b/drivers/of/of_pci.c
>> @@ -189,9 +189,7 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>> unsigned char busno, unsigned char bus_max,
>> struct list_head *resources, resource_size_t *io_base)
>> {
>> - struct resource_entry *window;
>> - struct resource *res;
>> - struct resource *bus_range;
>> + struct resource res;
>> struct of_pci_range range;
>> struct of_pci_range_parser parser;
>> char range_type[4];
>> @@ -200,24 +198,21 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>> if (io_base)
>> *io_base = (resource_size_t)OF_BAD_ADDR;
>>
>> - bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
>> - if (!bus_range)
>> - return -ENOMEM;
>> -
>> pr_info("host bridge %s ranges:\n", dev->full_name);
>>
>> - err = of_pci_parse_bus_range(dev, bus_range);
>> + err = of_pci_parse_bus_range(dev, &res);
>> if (err) {
>> - bus_range->start = busno;
>> - bus_range->end = bus_max;
>> - bus_range->flags = IORESOURCE_BUS;
>> - pr_info(" No bus range found for %s, using %pR\n",
>> - dev->full_name, bus_range);
>> + res.start = busno;
>> + res.end = bus_max;
>> + res.flags = IORESOURCE_BUS;
>> + pr_info(" No bus range found for %s\n", dev->full_name);
>> } else {
>> - if (bus_range->end > bus_range->start + bus_max)
>> - bus_range->end = bus_range->start + bus_max;
>> + if (res.end > res.start + bus_max)
>> + res.end = res.start + bus_max;
>> }
>> - pci_add_resource(resources, bus_range);
>> +
>> + res.flags |= IORESOURCE_AUTO;
>> + pci_add_resource(resources, &res);
>>
>> /* Check for ranges property */
>> err = of_pci_range_parser_init(&parser, dev);
>> @@ -244,24 +239,16 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>> if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
>> continue;
>>
>> - res = kzalloc(sizeof(struct resource), GFP_KERNEL);
>> - if (!res) {
>> - err = -ENOMEM;
>> - goto parse_failed;
>> - }
>> -
>> - err = of_pci_range_to_resource(&range, dev, res);
>> - if (err) {
>> - kfree(res);
>> + err = of_pci_range_to_resource(&range, dev, &res);
>> + if (err)
>> continue;
>> - }
>>
>> - if (resource_type(res) == IORESOURCE_IO) {
>> + if (resource_type(&res) == IORESOURCE_IO) {
>> if (!io_base) {
>> pr_err("I/O range found for %s. Please provide an io_base pointer to save CPU base address\n",
>> dev->full_name);
>> err = -EINVAL;
>> - goto conversion_failed;
>> + goto parse_failed;
>> }
>> if (*io_base != (resource_size_t)OF_BAD_ADDR)
>> pr_warn("More than one I/O resource converted for %s. CPU base address for old range lost!\n",
>> @@ -269,16 +256,14 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
>> *io_base = range.cpu_addr;
>> }
>>
>> - pci_add_resource_offset(resources, res, res->start - range.pci_addr);
>> + res.flags |= IORESOURCE_AUTO;
>> + pci_add_resource_offset(resources, &res,
>> + res.start - range.pci_addr);
>> }
>>
>> return 0;
>>
>> -conversion_failed:
>> - kfree(res);
>> parse_failed:
>> - resource_list_for_each_entry(window, resources)
>> - kfree(window->res);
>> pci_free_resource_list(resources);
>> return err;
>> }
>> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
>> index bc56cf1..3dbcb95 100644
>> --- a/drivers/pci/bus.c
>> +++ b/drivers/pci/bus.c
>> @@ -22,12 +22,17 @@ void pci_add_resource_offset(struct list_head *resources, struct resource *res,
>> {
>> struct resource_entry *entry;
>>
>> - entry = resource_list_create_entry(res, 0);
>> + entry = resource_list_create_entry(NULL, 0);
>
> If we make this change, there are no callers of
> resource_list_create_entry() that supply a non-NULL "res", so
> we could remove that argument completely.
>
>> if (!entry) {
>> printk(KERN_ERR "PCI: can't add host bridge window %pR\n", res);
>> return;
>> }
>>
>> + if (res->flags & IORESOURCE_AUTO)
>> + *entry->res = *res;
>> + else
>> + entry->res = res;
>> +
>> entry->offset = offset;
>> resource_list_add_tail(entry, resources);
>> }
>> --
>> 2.1.4
>>
>>
>
>
>
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