Messages in this thread | | | Subject | Re: [PATCH -next 1/3] PCI: fix double put_device() in error case in pci_create_root_bus() | From | Yang Yingliang <> | Date | Sat, 27 Aug 2022 17:15:25 +0800 |
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Hi,
On 2022/8/27 5:14, Bjorn Helgaas wrote: > [+cc Rob] > > On Thu, Aug 25, 2022 at 08:27:51PM +0800, Yang Yingliang wrote: >> If device_add() fails in pci_register_host_bridge(), the brigde device will >> be put once, and it will be put again in error path of pci_create_root_bus(). >> Move the put_device() from pci_create_root_bus() to pci_register_host_bridge() >> to fix this problem. And use device_unregister() instead of del_device() and >> put_device(). > s/brigde/bridge/ > >> Fixes: 9885440b16b8 ("PCI: Fix pci_host_bridge struct device release/free handling") > If you're fixing a commit from somebody else, please always cc: the > author because the author can help review the change. OK. > >> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> >> --- >> drivers/pci/probe.c | 8 ++------ >> 1 file changed, 2 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c >> index c5286b027f00..e500eb9d6468 100644 >> --- a/drivers/pci/probe.c >> +++ b/drivers/pci/probe.c >> @@ -1027,7 +1027,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) >> >> unregister: >> put_device(&bridge->dev); >> - device_del(&bridge->dev); >> + device_unregister(&bridge->dev); > I don't understand this part. device_unregister() looks like this: > > void device_unregister(struct device *dev) > { > device_del(dev); > put_device(dev); > } > > So this calls put_device(&bridge->dev) twice, doesn't it? > > The "unregister" label looks poorly named. We only get there if > device_register() *failed*. We shouldn't need to unregister anything > in that case. If it goes to the 'unregister' label, the bridge->dev has been register sucessfully (device_initialize() called from pci_alloc_host_bridge() and device_add() called from pci_register_host_bridge()), so it need be unregister, and another put_device() is for decreasing refcount of 'bus->bridge'.
Thanks, Yang > >> free: >> kfree(bus); >> @@ -3037,13 +3037,9 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus, >> >> error = pci_register_host_bridge(bridge); >> if (error < 0) >> - goto err_out; >> + return NULL; >> >> return bridge->bus; >> - >> -err_out: >> - put_device(&bridge->dev); >> - return NULL; > This part looks right to me. The get_device() is in > pci_register_host_bridge(), and if pci_register_host_bridge() returns > failure, I think it should first do the corresponding put_device(). > >> } >> EXPORT_SYMBOL_GPL(pci_create_root_bus); >> >> -- >> 2.25.1 >> > .
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