On Thu, Mar 23, 2017 at 5:58 PM, Dmitry Torokhov <d...@chromium.org> wrote:
> On Thu, Mar 23, 2017 at 3:07 PM, Rob Herring <r...@kernel.org> wrote:
>> On Thu, Mar 23, 2017 at 3:12 AM, Jeffy Chen <jeffy.c...@rock-chips.com>
>> wrote:
>>> Currently we only free the allocated resource struct when error.
>>> This would cause memory leak after pci_free_resource_list.
>>>
>>> Signed-off-by: Jeffy Chen <jeffy.c...@rock-chips.com>
>>> ---
>>>
>>> Changes in v2:
>>> Don't change the resource_list_create_entry's behavior.
>>>
>>> drivers/of/of_pci.c | 57
>>> +++++++++++++++++++++++------------------------------
>>> 1 file changed, 25 insertions(+), 32 deletions(-)
>>>
>>> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
>>> index 0ee42c3..a0ec246 100644
>>> --- a/drivers/of/of_pci.c
>>> +++ b/drivers/of/of_pci.c
>>> @@ -190,8 +190,7 @@ int of_pci_get_host_bridge_resources(struct device_node
>>> *dev,
>>> 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 +199,24 @@ 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;
>>> + }
>>> + window = pci_add_resource(resources, NULL);
>>> + if (!window) {
>>> + err = -ENOMEM;
>>> + goto parse_failed;
>>> }
>>> - pci_add_resource(resources, bus_range);
>>> + *window->res = res;
>>
>> Well, now this seems racy. You add a blank resource to the list first
>> and then fill it in.
>>
>
> Huh? There is absolutely no guarantees for concurrent access here.
> pcI_add_resource_offset() first adds a resource and then modifies
> offset. Here we add an empty resource and then fill it in.
I don't really like this pattern either. Even if there's no actual
racy behavior, it takes more analysis than necessary to figure that
out.
pci_add_resource_offset() allocates a resource list entry, sets the
offset, then adds it to the list. It doesn't update a resource entry
that might be visible to anybody else. Here we do update a resource
that is already visible to others because it's already on the list.
Bjorn
BTW, please CC linux-pci on the entire series so it's easier to
review. I don't know where you envision having this applied, but I
only apply things to the PCI tree after they appear on linux-pci.
