From: Maciej Fijalkowski maciej.fijalkowski@intel.com
[ Upstream commit d678cbd2f867a564a3c5b276c454e873f43f02f8 ]
xdpxceiver run on a AF_XDP ZC enabled driver revealed a problem with XSK Tx batching API. There is a test that checks how invalid Tx descriptors are handled by AF_XDP. Each valid descriptor is followed by invalid one on Tx side whereas the Rx side expects only to receive a set of valid descriptors.
In current xsk_tx_peek_release_desc_batch() function, the amount of available descriptors is hidden inside xskq_cons_peek_desc_batch(). This can be problematic in cases where invalid descriptors are present due to the fact that xskq_cons_peek_desc_batch() returns only a count of valid descriptors. This means that it is impossible to properly update XSK ring state when calling xskq_cons_release_n().
To address this issue, pull out the contents of xskq_cons_peek_desc_batch() so that callers (currently only xsk_tx_peek_release_desc_batch()) will always be able to update the state of ring properly, as total count of entries is now available and use this value as an argument in xskq_cons_release_n(). By doing so, xskq_cons_peek_desc_batch() can be dropped altogether.
Fixes: 9349eb3a9d2a ("xsk: Introduce batched Tx descriptor interfaces") Signed-off-by: Maciej Fijalkowski maciej.fijalkowski@intel.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Magnus Karlsson magnus.karlsson@intel.com Link: https://lore.kernel.org/bpf/20220607142200.576735-1-maciej.fijalkowski@intel... Signed-off-by: Sasha Levin sashal@kernel.org --- net/xdp/xsk.c | 5 +++-- net/xdp/xsk_queue.h | 8 -------- 2 files changed, 3 insertions(+), 10 deletions(-)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 404cbfde2f84..b9e70931c794 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -388,7 +388,8 @@ u32 xsk_tx_peek_release_desc_batch(struct xsk_buff_pool *pool, u32 max_entries) goto out; }
- nb_pkts = xskq_cons_peek_desc_batch(xs->tx, pool, max_entries); + max_entries = xskq_cons_nb_entries(xs->tx, max_entries); + nb_pkts = xskq_cons_read_desc_batch(xs->tx, pool, max_entries); if (!nb_pkts) { xs->tx->queue_empty_descs++; goto out; @@ -404,7 +405,7 @@ u32 xsk_tx_peek_release_desc_batch(struct xsk_buff_pool *pool, u32 max_entries) if (!nb_pkts) goto out;
- xskq_cons_release_n(xs->tx, nb_pkts); + xskq_cons_release_n(xs->tx, max_entries); __xskq_cons_release(xs->tx); xs->sk.sk_write_space(&xs->sk);
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h index b721795fe50c..491a18c1f786 100644 --- a/net/xdp/xsk_queue.h +++ b/net/xdp/xsk_queue.h @@ -278,14 +278,6 @@ static inline bool xskq_cons_peek_desc(struct xsk_queue *q, return xskq_cons_read_desc(q, desc, pool); }
-static inline u32 xskq_cons_peek_desc_batch(struct xsk_queue *q, struct xsk_buff_pool *pool, - u32 max) -{ - u32 entries = xskq_cons_nb_entries(q, max); - - return xskq_cons_read_desc_batch(q, pool, entries); -} - /* To improve performance in the xskq_cons_release functions, only update local state here. * Reflect this to global state when we get new entries from the ring in * xskq_cons_get_entries() and whenever Rx or Tx processing are completed in the NAPI loop.