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

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Date:   Tue, 14 Feb 2023 11:55:56 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [PATCH V3 1/2] usb: gadget: u_ether: Convert prints to device
 prints


On 13/02/2023 13:49, 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@...dia.com>
>> Tested-by: Jon Hunter <jonathanh@...dia.com>
>> ---
>> 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).

So dev_dbg() messages will only be printed if DEBUG is defined or if 
dynamic debug is enabled and the prints are enabled.

Greg, let me know what your thoughts on this version are?

Thanks
Jon

-- 
nvpublic