On 2012/9/12 21:11, Alan Stern wrote:
On Wed, 12 Sep 2012, Fengguang Wu wrote:
Hi Felipe,
FYI, there are new smatch warnings show up in
tree: git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git merge-result-for-greg
head: 23953bde3e4d6aa8780dc054f6ad9882ac63f4f4
commit: e918fa161f510136fce45a524e934fe20e62c8b1 [66/99] Merge tag 'gadget-for-v3.7' into merge-result-for-greg
drivers/usb/core/hub.c:2654 usb_get_hub_port_power_state() error: doing dma on the stack ((null))
drivers/usb/core/hub.c:4733 store_port_power_control() info: why not propagate 'ret' from set_port_feature() instead of -5?
drivers/usb/core/hub.c:4744 store_port_power_control() info: why not propagate 'ret' from clear_port_feature() instead of -5?
vim +2654 drivers/usb/core/hub.c
2644 return ret;
2645 }
2646
2647 static int usb_get_hub_port_power_state(struct usb_device *hdev, int port1)
2648 {
2649 struct usb_hub *hub = hdev_to_hub(hdev);
2650 struct usb_port_status data;
2651 u16 portstatus;
2652 int ret;
2653
2654 ret = get_port_status(hub->hdev, port1, &data);
2655 if (ret < 4) {
2656 dev_err(hub->intfdev,
2657 "%s failed (err = %d)\n", __func__, ret);
2658 if (ret >= 0)
2659 ret = -EIO;
2660 return ret;
2661 } else
2662 portstatus = le16_to_cpu(data.wPortStatus);
2663 return port_is_power_on(hub, portstatus);
2664 }
This is a real problem. It looks like it really is necessary to call
hub_port_status() here, not get_port_status(). Would you like to fix
this?
Yeah. I'd like to fix it.
The reason for changing the return codes from clear_port_feature() and
set_port_feature() is simple. The values they return are meant for
internal use within the kernel, whereas the return code from
store_port_power_control() will be passed back to userspace.
Alan Stern
--
Best Regards
Tianyu Lan
linux kernel enabling team
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