Re: [PATCH] "volatile considered harmful" document

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> In Ethernet drivers, for example, it is common for the network card to
> maintain a pointer in host memory the the latest descriptor written; you
> will generally have a loop of the form:
> 
> 	while ((this_pointer = *pointer_ptr) > my_last_pointer) {
> 		for (pkt = my_last_pointer; pkt < this_pointer; pkt++)
> 			receeive_packet(pkt);
> 		my_last_pointer = this_pointer;
> 	}
> 
> pointer_p can then be a volatile pointer into said coherent memory.

True but you can happily use rmb/wmb for this which are clearer and fit
the rest of the Linux model better.

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