[PATCH io_uring-7.1 14/16] io_uring/zcrx: cache fallback availability in zcrx ctx
From: Pavel Begunkov <asml.silence@gmail.com>
Date: 2026-03-23 12:44:20
Also in:
io-uring
Subsystem:
io_uring, io_uring zcrx, the rest · Maintainers:
Jens Axboe, Pavel Begunkov, Linus Torvalds
Store a flag in struct io_zcrx_ifq telling if the backing memory is normal page or dmabuf based. It was looking it up from the area, however it logically allocates from the zcrx ctx and not a particular area, and once we add more than one area it'll become a mess. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- io_uring/zcrx.c | 9 ++++++++- io_uring/zcrx.h | 1 + 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 265b3a744ac2..d6475f95b815 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c@@ -423,8 +423,13 @@ static void io_zcrx_free_area(struct io_zcrx_ifq *ifq, static int io_zcrx_append_area(struct io_zcrx_ifq *ifq, struct io_zcrx_area *area) { + bool kern_readable = !area->mem.is_dmabuf; + if (WARN_ON_ONCE(ifq->area)) return -EINVAL; + if (WARN_ON_ONCE(ifq->kern_readable != kern_readable)) + return -EINVAL; + ifq->area = area; return 0; }
@@ -882,6 +887,8 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx, if (ret) goto err; + ifq->kern_readable = !(area.flags & IORING_ZCRX_AREA_DMABUF); + if (!(reg.flags & ZCRX_REG_NODEV)) { ret = zcrx_register_netdev(ifq, ®, &area); if (ret)
@@ -1296,7 +1303,7 @@ static struct net_iov *io_alloc_fallback_niov(struct io_zcrx_ifq *ifq) struct io_zcrx_area *area = ifq->area; struct net_iov *niov = NULL; - if (area->mem.is_dmabuf) + if (!ifq->kern_readable) return NULL; scoped_guard(spinlock_bh, &area->freelist_lock)
diff --git a/io_uring/zcrx.h b/io_uring/zcrx.h
index 893cd3708a06..3e07238a4eb0 100644
--- a/io_uring/zcrx.h
+++ b/io_uring/zcrx.h@@ -54,6 +54,7 @@ struct io_zcrx_ifq { unsigned niov_shift; struct user_struct *user; struct mm_struct *mm_account; + bool kern_readable; struct zcrx_rq rq ____cacheline_aligned_in_smp;
--
2.53.0