On Fri, 24 Mar 2023 at 13:22, Maciej Fijalkowski
<maciej.fijalkowski@xxxxxxxxx> wrote:
>
> On Fri, Mar 24, 2023 at 10:02:22AM +0000, Nuno Gonçalves wrote:
> > The remap of fill and completion rings was frowned upon as they
> > control the usage of UMEM which does not support concurrent use.
> > At the same time this would disallow the remap of these rings
> > into another process.
> >
> > A possible use case is that the user wants to transfer the socket/
> > UMEM ownership to another process (via SYS_pidfd_getfd) and so
> > would need to also remap these rings.
> >
> > This will have no impact on current usages and just relaxes the
> > remap limitation.
> >
> > Signed-off-by: Nuno Gonçalves <nunog@xxxxxxxx>
> > ---
> > V3 -> V4: Remove undesired format changes
> > V2 -> V3: Call READ_ONCE for each variable and not for the ternary operator
> > V1 -> V2: Format and comment changes
>
> thanks, it now looks good to me, i applied this locally and it builds, so:
> Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
>
> but i am giving a last call to Magnus since he was acking this before.
I have already acked it, but I can do it twice.
Acked-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
> >
> > net/xdp/xsk.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> > index 2ac58b282b5eb..cc1e7f15fa731 100644
> > --- a/net/xdp/xsk.c
> > +++ b/net/xdp/xsk.c
> > @@ -1301,9 +1301,10 @@ static int xsk_mmap(struct file *file, struct socket *sock,
> > loff_t offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
> > unsigned long size = vma->vm_end - vma->vm_start;
> > struct xdp_sock *xs = xdp_sk(sock->sk);
> > + int state = READ_ONCE(xs->state);
> > struct xsk_queue *q = NULL;
> >
> > - if (READ_ONCE(xs->state) != XSK_READY)
> > + if (state != XSK_READY && state != XSK_BOUND)
> > return -EBUSY;
> >
> > if (offset == XDP_PGOFF_RX_RING) {
> > @@ -1314,9 +1315,11 @@ static int xsk_mmap(struct file *file, struct socket *sock,
> > /* Matches the smp_wmb() in XDP_UMEM_REG */
> > smp_rmb();
> > if (offset == XDP_UMEM_PGOFF_FILL_RING)
> > - q = READ_ONCE(xs->fq_tmp);
> > + q = state == XSK_READY ? READ_ONCE(xs->fq_tmp) :
> > + READ_ONCE(xs->pool->fq);
> > else if (offset == XDP_UMEM_PGOFF_COMPLETION_RING)
> > - q = READ_ONCE(xs->cq_tmp);
> > + q = state == XSK_READY ? READ_ONCE(xs->cq_tmp) :
> > + READ_ONCE(xs->pool->cq);
> > }
> >
> > if (!q)
> > --
> > 2.40.0
> >
