2021-07-24 18:37:54

by Salah Triki

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Subject: [PATCH] wireless: rtl8187: replace udev with usb_get_dev()

Replace udev with usb_get_dev() in order to make code cleaner.

Signed-off-by: Salah Triki <[email protected]>
---
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
index eb68b2d3caa1..30bb3c2b8407 100644
--- a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
+++ b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
@@ -1455,9 +1455,7 @@ static int rtl8187_probe(struct usb_interface *intf,

SET_IEEE80211_DEV(dev, &intf->dev);
usb_set_intfdata(intf, dev);
- priv->udev = udev;
-
- usb_get_dev(udev);
+ priv->udev = usb_get_dev(udev);

skb_queue_head_init(&priv->rx_queue);

--
2.25.1


2021-07-25 06:35:17

by Greg Kroah-Hartman

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Subject: Re: [PATCH] wireless: rtl8187: replace udev with usb_get_dev()

On Sat, Jul 24, 2021 at 08:54:34PM +0000, Hin-Tak Leung wrote:
>
>
> On Saturday, 24 July 2021, 19:35:12 BST, Salah Triki <[email protected]> wrote:
>
>
> > Replace udev with usb_get_dev() in order to make code cleaner.
>
> > Signed-off-by: Salah Triki <[email protected]>
> > ---
> > drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 4 +---
> > 1 file changed, 1 insertion(+), 3 deletions(-)
>
> > diff --git a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
> > index eb68b2d3caa1..30bb3c2b8407 100644
> > --- a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
> > +++ b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
> > @@ -1455,9 +1455,7 @@ static int rtl8187_probe(struct usb_interface *intf,
>
> > ??? SET_IEEE80211_DEV(dev, &intf->dev);
> > ??? usb_set_intfdata(intf, dev);
> > -??? priv->udev = udev;
> > -
> > -??? usb_get_dev(udev);
> > +??? priv->udev = usb_get_dev(udev);
>
> > ??? skb_queue_head_init(&priv->rx_queue);
>
> > --
> > 2.25.1
>
> It is not cleaner - the change is not functionally equivalent. Before the change, the reference count is increased after the assignment; and after the change, before the assignment. So my question is, does the reference count increasing a little earlier matters? What can go wrong between very short time where the reference count increases, and priv->udev not yet assigned? I think there might be a race condition where the probbe function is called very shortly twice.
> Especially if the time of running the reference count function is non-trivial.

Probe functions are called in order, this should not be an issue.

This patch changes nothing, I do not think it is needed at all.

thanks,

greg k-h