Re: [PATCH] video/saa7164: Fix sparse warning: Using plain integer as NULL pointer

From: Peter Hüwe
Date: Tue Jan 25 2011 - 17:54:43 EST

Am Dienstag 25 Januar 2011, 23:20:44 schrieb Julia Lawall:
> On Tue, 25 Jan 2011, Peter Huewe wrote:
> > This patch fixes the warning "Using plain integer as NULL pointer",
> > generated by sparse, by replacing the offending 0s with NULL.
> I recall (a number of years ago) being told that for things like kmalloc,
> the proper test was !x, not x == NULL.
> julia

Hi Julia,

thanks for your input.
So do I understand you correctly if I say
if(!x) is better than if(x==NULL) in any case?

Or only for the kmalloc family?

Do you remember the reason why !x should be preferred?

In Documentation/CodingStyle , Chapter 7: Centralized exiting of functions
there is a function fun with looks like this:
int fun(int a)
int result = 0;
char *buffer = kmalloc(SIZE);

if (buffer == NULL)
return -ENOMEM;

if (condition1) {
while (loop1) {
result = 1;
goto out;
return result;

--> So if (buffer == NULL) is in the official CodingStyle - maybe we should
add a paragraph there as well ;)

Don't get me wrong, I just want to learn ;)


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