On mercoledì 11 gennaio 2023 17:02:26 CET Al Viro wrote:
> 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...
Actually, I'd prefer Ira's solution for readability, but I have nothing
against yours. I will send you the code in the way you rewrote it.
> > >> 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.
Yes, I missed it :-(
However, with the use of memcpy_to_page() we no longer need that explicit call
to flush_dcache_page().
Thank you,
Fabio
