Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*

[Andrew Lutomirski]

On Mon, Apr 21, 2014 at 6:14 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> I wanted to avoid the "another cpu made this allocation, now I have to free" crap, but I also didn't want to grab the lock if there was no work needed.

I guess you also want to avoid bouncing all these cachelines around on
boot on bit multicore machines.

I'd advocate using the bitmap approach or simplifying the existing
code.  For example:

+       for (n = 0; n < ESPFIX_PUD_CLONES; n++) {
+               pud = ACCESS_ONCE(pud_p[n]);
+               if (!pud_present(pud))
+                       return false;
+       }

I don't see why that needs to be a loop.  How can one clone exist but
not the others?

--Andy
--
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/