On Mon, Jun 19, 2023 at 07:31:21AM -0700, Dave Hansen wrote: > On 6/19/23 04:43, Huang, Kai wrote: > > On Mon, 2023-06-12 at 06:47 -0700, Dave Hansen wrote: > >> On 6/12/23 03:27, Huang, Kai wrote: > >>> So I think a __mb() after setting tdmr->pamt_4k_base should be good enough, as > >>> it guarantees when setting to any pamt_*_size happens, the valid pamt_4k_base > >>> will be seen by other cpus. > >>> > >>> Does it make sense? > >> Just use a normal old atomic_t or set_bit()/test_bit(). They have > >> built-in memory barriers are are less likely to get botched. > > Hi Dave, > > > > Using atomic_set() requires changing tdmr->pamt_4k_base to atomic_t, which is a > > little bit silly or overkill IMHO. Looking at the code, it seems > > arch_atomic_set() simply uses __WRITE_ONCE(): > > How about _adding_ a variable that protects tdmr->pamt_4k_base? > Wouldn't that be more straightforward than mucking around with existing > types? What's wrong with simple global spinlock that protects all tdmr->pamt_*? It is much easier to follow than a custom serialization scheme. -- Kiryl Shutsemau / Kirill A. Shutemov
