linux-kernel - A simple question of sys

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Date:	Fri, 17 Sep 2010 14:58:30 +0800
From:	Rofail Qu <rofail@...il.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: A simple question of sys_

How to use macro IS_ERR() ?

It defines as,
...
#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
static inline long __must_check IS_ERR(const void *ptr)
{
	return IS_ERR_VALUE((unsigned long)ptr);
}
...
so when pass x as a pointer and x>=-MAX_ERRNO (including NULL or any
valid address),
IS_ERR() will return true!
IS_ERR(x) seems to use on judge if "x" is a valid error number, right?

So in sys_execve(),
...
        long error;
	char* filename;

	filename = getname(name);
	error = PTR_ERR(filename);
	if (IS_ERR(filename))     // <== should be IS_ERR((void *)error) or other?
		return error;
	error = do_execve(filename, argv, envp, regs);
...

Where i am wrong?
Thanks.
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