Re: [PATCH v2] media: vb2: vmalloc-based allocator user pointer handling

[Sylwester Nawrocki <snjw23@gmail.com>]

Hi Laurent,

On 12/08/2011 11:56 AM, Laurent Pinchart wrote:
> On Wednesday 07 December 2011 17:29:06 Marek Szyprowski wrote:
>> From: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
[...]
>> -	printk(KERN_DEBUG "Allocated vmalloc buffer of size %ld at vaddr=%p\n",
>> -			buf->size, buf->vaddr);
>> +	pr_err("Allocated vmalloc buffer of size %ld at vaddr=%p\n", buf->size,
>> +	       buf->vaddr);
> 
> Turning KERN_DEBUG into pr_err() is a bit harsh :-) In my opinion even 
> KERN_DEBUG is too much here, I don't want to get messages printed to the 
> kernel log every time I allocate buffers.

Indeed, pr_err looks like an overkill:) I think pr_debug() would be fine here.

> 
>>  	return buf;
>>  }
>> @@ -59,13 +63,87 @@ static void vb2_vmalloc_put(void *buf_priv)
>>  	struct vb2_vmalloc_buf *buf = buf_priv;
>>
>>  	if (atomic_dec_and_test(&buf->refcount)) {
>> -		printk(KERN_DEBUG "%s: Freeing vmalloc mem at vaddr=%p\n",
>> -			__func__, buf->vaddr);
>> +		pr_debug("%s: Freeing vmalloc mem at vaddr=%p\n", __func__,
>> +			 buf->vaddr);
> 
> Same here. Should we get rid of those two messages, or at least conditionally-
> compile them out of the kernel by default ?

During compilation pr_debug() will most likely be optimized away if DEBUG and
CONFIG_DYNAMIC_DEBUG isn't defined, as it is then defined as:

static inline __printf(1, 2)
int no_printk(const char *fmt, ...)
{
	return 0;
}

Plus it's easy with pr_debug() to enable debug trace while dynamic printk()
is enabled in the kernel configuration.

--

Regards,
Sylwester