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xsk: allow remap of fill and/or completion rings

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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@fr24.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/r/20230324100222.13434-1-nunog@fr24.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Nuno Gonçalves 2023-03-24 10:02:22 +00:00 committed by Alexei Starovoitov
parent 8cfee11071
commit 5f5a7d8d8b
1 changed files with 6 additions and 3 deletions
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9
net/xdp/xsk.c
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@ -1301,9 +1301,10 @@ static int xsk_mmap(struct file *file, struct socket *sock,
loff_t offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; loff_t offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
unsigned long size = vma->vm_end - vma->vm_start; unsigned long size = vma->vm_end - vma->vm_start;
struct xdp_sock *xs = xdp_sk(sock->sk); struct xdp_sock *xs = xdp_sk(sock->sk);
int state = READ_ONCE(xs->state);
struct xsk_queue *q = NULL; struct xsk_queue *q = NULL;
if (READ_ONCE(xs->state) != XSK_READY) if (state != XSK_READY && state != XSK_BOUND)
return -EBUSY; return -EBUSY;
if (offset == XDP_PGOFF_RX_RING) { 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 */ /* Matches the smp_wmb() in XDP_UMEM_REG */
smp_rmb(); smp_rmb();
if (offset == XDP_UMEM_PGOFF_FILL_RING) 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) 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) if (!q)