Re: Being more anal about iospace accesses..

[Chris Wedgwood]

On Wed, Sep 15, 2004 at 10:07:29AM -0700, Linus Torvalds wrote:

> C doesn't. gcc does. It's a documented extension, and it acts like
> if it was done on a byte.

[...]

> It's a singularly good feature.

I dunno about that.  Maybe it is, but it has some gotchas.

Recently when doing a sparsification of code I noticed there are
places which essentially do things like:

    void *foo;

    [...]

    foo += bar * n;

Part of the fix (cleanup) was to change the 'void *foo' to
'gratuitous_typedef_t __user *foo' --- which silently breaks the math
if you don't explicitly check for this.


  --cw
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/