Hi Bjorn,
On 04/05/2017 03:18 AM, Bjorn Helgaas wrote:
On Thu, Mar 23, 2017 at 5:58 PM, Dmitry Torokhov <dtor@xxxxxxxxxxxx> wrote:
On Thu, Mar 23, 2017 at 3:07 PM, Rob Herring <robh@xxxxxxxxxx> wrote:
On Thu, Mar 23, 2017 at 3:12 AM, Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx> 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.chen@xxxxxxxxxxxxxx>
---
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.
i was following ./drivers/pnp/resource.c, but i'm agree this is not a
good way.
i'll upload a new version to fix this in another way. more ideas:
1/ pass a struct device to of_pci_get_host_bridge_resources and use
devm_kzalloc
2/ add a new type of flags(or reuse IORESOURCE_AUTO) to tell
pci_free_resource_list to kfree them)
3/ add new helpers of of_pci_add_resource[_offset] to alloc empty res,
fill it, add to 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.
oh, sorry, didn't notice that, will do in next version.
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