netdev - [PATCH net v2 2/2] net: avoid false positive warnings in __net_mp_close

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Message-ID: <20250403013405.2827250-3-kuba@kernel.org>
Date: Wed,  2 Apr 2025 18:34:05 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	ap420073@...il.com,
	almasrymina@...gle.com,
	asml.silence@...il.com,
	dw@...idwei.uk,
	sdf@...ichev.me,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net v2 2/2] net: avoid false positive warnings in __net_mp_close_rxq()

Commit under Fixes solved the problem of spurious warnings when we
uninstall an MP from a device while its down. The __net_mp_close_rxq()
which is used by io_uring was not fixed. Move the fix over and reuse
__net_mp_close_rxq() in the devmem path.

Acked-by: Stanislav Fomichev <sdf@...ichev.me>
Fixes: a70f891e0fa0 ("net: devmem: do not WARN conditionally after netdev_rx_queue_restart()")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
v2:
 - don't split the registration check, it may cause a race if we just
   bail on the registration state and not on the MP being present,
   as we drop and re-take the instance lock after setting reg_state
v1: https://lore.kernel.org/20250331194308.2026940-1-kuba@kernel.org
---
 net/core/devmem.c          | 12 +++++-------
 net/core/netdev_rx_queue.c |  4 +++-
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/core/devmem.c b/net/core/devmem.c
index f2ce3c2ebc97..6e27a47d0493 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -116,21 +116,19 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 	struct netdev_rx_queue *rxq;
 	unsigned long xa_idx;
 	unsigned int rxq_idx;
-	int err;
 
 	if (binding->list.next)
 		list_del(&binding->list);
 
 	xa_for_each(&binding->bound_rxqs, xa_idx, rxq) {
-		WARN_ON(rxq->mp_params.mp_priv != binding);
-
-		rxq->mp_params.mp_priv = NULL;
-		rxq->mp_params.mp_ops = NULL;
+		const struct pp_memory_provider_params mp_params = {
+			.mp_priv	= binding,
+			.mp_ops		= &dmabuf_devmem_ops,
+		};
 
 		rxq_idx = get_netdev_rx_queue_index(rxq);
 
-		err = netdev_rx_queue_restart(binding->dev, rxq_idx);
-		WARN_ON(err && err != -ENETDOWN);
+		__net_mp_close_rxq(binding->dev, rxq_idx, &mp_params);
 	}
 
 	xa_erase(&net_devmem_dmabuf_bindings, binding->id);
diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index 556b5393ec9f..d126f10197bf 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -154,6 +154,7 @@ void __net_mp_close_rxq(struct net_device *dev, unsigned int ifq_idx,
 			const struct pp_memory_provider_params *old_p)
 {
 	struct netdev_rx_queue *rxq;
+	int err;
 
 	if (WARN_ON_ONCE(ifq_idx >= dev->real_num_rx_queues))
 		return;
@@ -173,7 +174,8 @@ void __net_mp_close_rxq(struct net_device *dev, unsigned int ifq_idx,
 
 	rxq->mp_params.mp_ops = NULL;
 	rxq->mp_params.mp_priv = NULL;
-	WARN_ON(netdev_rx_queue_restart(dev, ifq_idx));
+	err = netdev_rx_queue_restart(dev, ifq_idx);
+	WARN_ON(err && err != -ENETDOWN);
 }
 
 void net_mp_close_rxq(struct net_device *dev, unsigned ifq_idx,
-- 
2.49.0