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

[Salil Mehta <salil.mehta@huawei.com>]

> From: John Garry
> Sent: Friday, February 15, 2019 12:00 PM
> 
> 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.


Yes, in the positive leg the put_device() was missing. Thanks for identifying!
I have floated the patch to fix it https://www.lkml.org/lkml/2019/2/18/1161


Salil.