On Wed, Jan 11, 2023 at 09:13:40AM -0500, Jeff Moyer wrote:
> Hi, Al,
>
> Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes:
>
> > On Mon, Jan 09, 2023 at 06:56:29PM +0100, Fabio M. De Francesco wrote:
> >
> >> - ring = kmap_atomic(ctx->ring_pages[0]);
> >> + ring = kmap_local_page(ctx->ring_pages[0]);
> >> ring->nr = nr_events; /* user copy */
> >> ring->id = ~0U;
> >> ring->head = ring->tail = 0;
> >> @@ -575,7 +575,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
> >> ring->compat_features = AIO_RING_COMPAT_FEATURES;
> >> ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
> >> ring->header_length = sizeof(struct aio_ring);
> >> - kunmap_atomic(ring);
> >> + kunmap_local(ring);
> >> flush_dcache_page(ctx->ring_pages[0]);
> >
> > I wonder if it would be more readable as memcpy_to_page(), actually...
>
> I'm not sure I understand what you're suggesting.
memcpy_to_page(ctx->ring_pages[0], 0, &(struct aio_ring){
.nr = nr_events, .id = ~0U, .magic = AIO_RING_MAGIC,
.compat_features = AIO_RING_COMPAT_FEATURES,
.in_compat_features = AIO_RING_INCOMPAT_FEATURES,
.header_length = sizeof(struct aio_ring)},
sizeof(struct aio_ring));
instead of the lines from kmap_atomic to flush_dcache_page...
>
> >>
> >> return 0;
> >> @@ -678,9 +678,9 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
> >> * we are protected from page migration
> >> * changes ring_pages by ->ring_lock.
> >> */
> >> - ring = kmap_atomic(ctx->ring_pages[0]);
> >> + ring = kmap_local_page(ctx->ring_pages[0]);
> >> ring->id = ctx->id;
> >> - kunmap_atomic(ring);
> >> + kunmap_local(ring);
> >
> > Incidentally, does it need flush_dcache_page()?
>
> Yes, good catch.
