Re: [PATCH V3 1/2] usb: gadget: u_ether: Convert prints to device prints

[Greg Kroah-Hartman]

On Mon, Feb 13, 2023 at 02:49:46PM +0100, Andrzej Pietrasiewicz wrote:
> Hi Jon,
> 
> W dniu 9.02.2023 o 13:53, Jon Hunter pisze:
> > The USB ethernet gadget driver implements its own print macros which
> > call printk. Device drivers should use the device prints that print the
> > device name. Fortunately, the same macro names are defined in the header
> > file 'linux/usb/composite.h' and these use the device prints. Therefore,
> > remove the local definitions in the USB ethernet gadget driver and use
> > those in 'linux/usb/composite.h'. The only difference is that now the
> > device name is printed instead of the ethernet interface name.
> > 
> > Tested using ethernet gadget on Jetson AGX Orin.
> > 
> > Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> > Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> > ---
> > V3: Added this patch and dropped the patch in V2 that improved some of
> >      the prints.
> > 
> >   drivers/usb/gadget/function/u_ether.c | 36 +--------------------------
> >   1 file changed, 1 insertion(+), 35 deletions(-)
> > 
> > diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
> > index 8f12f3f8f6ee..740331882e8d 100644
> > --- a/drivers/usb/gadget/function/u_ether.c
> > +++ b/drivers/usb/gadget/function/u_ether.c
> > @@ -17,6 +17,7 @@
> >   #include <linux/etherdevice.h>
> >   #include <linux/ethtool.h>
> >   #include <linux/if_vlan.h>
> > +#include <linux/usb/composite.h>
> >   #include "u_ether.h"
> > @@ -103,41 +104,6 @@ static inline int qlen(struct usb_gadget *gadget, unsigned qmult)
> >   /*-------------------------------------------------------------------------*/
> > -/* REVISIT there must be a better way than having two sets
> > - * of debug calls ...
> > - */
> > -
> > -#undef DBG
> > -#undef VDBG
> > -#undef ERROR
> > -#undef INFO
> > -
> > -#define xprintk(d, level, fmt, args...) \
> > -	printk(level "%s: " fmt , (d)->net->name , ## args)
> > -
> > -#ifdef DEBUG
> > -#undef DEBUG
> > -#define DBG(dev, fmt, args...) \
> > -	xprintk(dev , KERN_DEBUG , fmt , ## args)
> > -#else
> > -#define DBG(dev, fmt, args...) \
> > -	do { } while (0)
> > -#endif /* DEBUG */
> 
> Actually there are more (at least hypothetical) changes than the declared
> change of printed device name.
> 
> If DEBUG is not set there can be _more_ messages printed
> when your patch is applied as-is (i.e. all DBG() invocations will
> expand into some dev_dbg(), whereas before the patch is applied
> they compile into nothing).

But if you do not manually set the call to dev_dbg() to be printed out,
it will not, so there should not be any functional change here.

thanks,

greg k-h