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SubjectRe: [PATCH] net: hns: Fix object reference leaks in hns_dsaf_roce_reset()
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On 15/02/2019 11:25, Salil Mehta wrote:
>> From: John Garry
>> Sent: Friday, February 15, 2019 10:52 AM
>>
>> On 14/02/2019 06:41, Huang Zijiang wrote:
>>> The of_find_device_by_node() takes a reference to the underlying device
>>> structure, we should release that reference.
>>
>> of_find_device_by_node() is not called for every path, so is this change proper:
>
>
> It looks okay to me and with the suggested device reference is being
> released from every possible error leg in the function. Could you be
> more specific which error path is not being addressed?
>
>
>
>> /* find the platform device corresponding to fwnode */
>> if (is_of_node(dsaf_fwnode)) {
>> pdev = of_find_device_by_node(to_of_node(dsaf_fwnode));
>
>
> This will get the reference to the device, which needs to be
> released later.
>
>
>> } else if (is_acpi_device_node(dsaf_fwnode)) {
>> pdev = hns_dsaf_find_platform_device(dsaf_fwnode);
>
>
> This will also get the reference to the device when bus_find_device()
> gets called and returns the 'device'. Therefore, this needs to be
> released as well using put_device()

OK, I see. That's non-obvious.

And so the commit message was simply incomplete.

>

So who finally drops this reference? This patch only seems to release on
error path. I checked the callers and they don't seem to.

John

>
>
>> } else {
>> pr_err("fwnode is neither OF or ACPI type\n");
>> return -EINVAL;
>> }
>>
>> /* check if we were a success in fetching pdev */
>> if (!pdev) {
>> pr_err("couldn't find platform device for node\n");
>> return -ENODEV;
>> }
>>
>> /* retrieve the dsaf_device from the driver data */
>> dsaf_dev = dev_get_drvdata(&pdev->dev);
>> if (!dsaf_dev) {
>> dev_err(&pdev->dev, "dsaf_dev is NULL\n");
>> return -ENODEV;
>> }
>>
>> John
>
>
> [...]
>
>>> --- a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.c
>>> +++ b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.c
>>> @@ -3081,6 +3081,7 @@ int hns_dsaf_roce_reset(struct fwnode_handle *dsaf_fwnode, bool dereset)
>>> dsaf_dev = dev_get_drvdata(&pdev->dev);
>>> if (!dsaf_dev) {
>>> dev_err(&pdev->dev, "dsaf_dev is NULL\n");
>>> + put_device(&pdev->dev);
>
>
> This looks okay.
>
>
>>> return -ENODEV;
>>> }
>>>
>>> @@ -3088,6 +3089,7 @@ int hns_dsaf_roce_reset(struct fwnode_handle *dsaf_fwnode, bool dereset)
>>> if (AE_IS_VER1(dsaf_dev->dsaf_ver)) {
>>> dev_err(dsaf_dev->dev, "%s v1 chip doesn't support RoCE!\n",
>>> dsaf_dev->ae_dev.name);
>>> + put_device(&pdev->dev);
>
>
> This looks okay.
>
>
> Salil.
>
> .
>


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