netdev - [PATCH net v3] net: spacemit: Check netif_running() in emac_set

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Message-Id: <20251103-k1-ethernet-remove-fc-v3-1-2083770cd282@iscas.ac.cn>
Date: Mon, 03 Nov 2025 10:02:49 +0800
From: Vivian Wang <wangruikang@...as.ac.cn>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Yixun Lan <dlan@...too.org>, 
 Maxime Chevallier <maxime.chevallier@...tlin.com>, 
 Troy Mitchell <troy.mitchell@...ux.spacemit.com>, 
 Vadim Fedorenko <vadim.fedorenko@...ux.dev>, 
 Vivian Wang <wangruikang@...as.ac.cn>
Cc: netdev@...r.kernel.org, linux-riscv@...ts.infradead.org, 
 spacemit@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH net v3] net: spacemit: Check netif_running() in
 emac_set_pauseparam()

Currently, emac_set_pauseparam() will oops if userspace calls it while
the interface is not up, because phydev is NULL, but it is still
accessed in emac_set_fc() and emac_set_fc_autoneg().

Check for netif_running(dev) in emac_set_pauseparam() before proceeding.

Fixes: bfec6d7f2001 ("net: spacemit: Add K1 Ethernet MAC")
Signed-off-by: Vivian Wang <wangruikang@...as.ac.cn>
---
This more urgent problem was discovered while trying to fix
emac_set_pauseparam() (v1 of that has already been sent to the mailing
lists [1], but it was still bad), so I decided to send this patch for
the net tree now so that this oops will not happen on 6.18. A future
version of the proper flow control implementation will be sent to
net-next.

[1]: https://lore.kernel.org/spacemit/20251030-k1-ethernet-fix-autoneg-v1-1-baa572607ccc@iscas.ac.cn
---
Changes in v3:
- Check netif_running() instead (Andrew)
- Add back blurb about the attempt to fix flow control for context
- Link to v2: https://lore.kernel.org/r/20251101-k1-ethernet-remove-fc-v2-1-014ac3bc280e@iscas.ac.cn

Changes in v2:
- Reduced patch to only contain checking IFF_UP to avoid the oops. More
  invasive changes will be sent to net-next in the future. (Andrew)
- Link to v1: https://lore.kernel.org/r/20251031-k1-ethernet-remove-fc-v1-1-1ae3f1d6508c@iscas.ac.cn
---
 drivers/net/ethernet/spacemit/k1_emac.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/spacemit/k1_emac.c b/drivers/net/ethernet/spacemit/k1_emac.c
index e1c5faff3b71..220eb5ce7583 100644
--- a/drivers/net/ethernet/spacemit/k1_emac.c
+++ b/drivers/net/ethernet/spacemit/k1_emac.c
@@ -1441,6 +1441,9 @@ static int emac_set_pauseparam(struct net_device *dev,
 	struct emac_priv *priv = netdev_priv(dev);
 	u8 fc = 0;

+	if (!netif_running(dev))
+		return -ENETDOWN;
+
 	priv->flow_control_autoneg = pause->autoneg;

 	if (pause->autoneg) {

---
base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
change-id: 20251031-k1-ethernet-remove-fc-82fd67d889a6

Best regards,
-- 
Vivian "dramforever" Wang