[PATCH bpf-next V4] xsk: allow remap of fill and/or completion rings
From: Nuno Gonçalves <hidden>
Date: 2023-03-24 10:02:53
Also in:
bpf, lkml
Subsystem:
networking [general], the rest, xdp sockets (af_xdp) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
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 <redacted> --- 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 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