RE: [PATCH net-next v2 8/9] Altera TSE: Add Miscellaneous Files for Altera Ethernet Driver

From: Vince Bridgers

On Mon, Mar 10, 2014 at 7:40 PM, Stephen Hemminger
[off-list ref] wrote:

quoted

On Mon, 10 Mar 2014 18:14:36 -0500
Vince Bridgers [off-list ref] wrote:

quoted

+
+     buf[0] = (u64) ioread32(&mac->frames_transmitted_ok);

The cast to u64 is not really necessary, C will do it for you.
You do need the cast to do the shift for the 64 bit values.

Ok, understood. I generally add the cast so it's explicit, but I'll modify.

The problem is that the cast will allow incorrect code to compile.
eg, you might have a pointer, not an integer.

Many years ago I got caught out by a #define like the following:
#define foo(ptr) { int s = splhi(); do_foo((void *)ptr); splx(s); }
My code crashed because I'd called foo(s).
Now that #define is broken in so many ways, but the (void *) cast
stopped the compiler erroring one of them.

	David