Re: [PATCH] net: hns: Fix object reference leaks in hns_dsaf_roce_reset()

[John Garry]

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.

.