Re: [PATCH 2/2] net: ethernet: ti: am65-cpsw: avoid devm_alloc_etherdev, fix module removal

From: Paolo Abeni
Date: Thu Oct 03 2024 - 04:34:37 EST


On 9/27/24 04:53, Nicolas Pitre wrote:
From: Nicolas Pitre <npitre@xxxxxxxxxxxx>

Usage of devm_alloc_etherdev_mqs() conflicts with
am65_cpsw_nuss_cleanup_ndev() as the same struct net_device instances
get unregistered twice. Switch to alloc_etherdev_mqs() and make sure
am65_cpsw_nuss_cleanup_ndev() unregisters and frees those net_device
instances properly.

With this, it is finally possible to rmmod the driver without oopsing
the kernel.

Signed-off-by: Nicolas Pitre <npitre@xxxxxxxxxxxx>

This patch and the previous one looks like fixes for the 'net' tree: you should include the 'net' target into the subj prefix and include a suitable fixes tag in the tag area, see:

https://elixir.bootlin.com/linux/v6.12-rc1/source/Documentation/process/maintainer-netdev.rst#L67

---
drivers/net/ethernet/ti/am65-cpsw-nuss.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index f6bc8a4dc6..4cb1c187c6 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -2744,10 +2744,9 @@ am65_cpsw_nuss_init_port_ndev(struct am65_cpsw_common *common, u32 port_idx)
return 0;
/* alloc netdev */
- port->ndev = devm_alloc_etherdev_mqs(common->dev,
- sizeof(struct am65_cpsw_ndev_priv),
- AM65_CPSW_MAX_QUEUES,
- AM65_CPSW_MAX_QUEUES);
+ port->ndev = alloc_etherdev_mqs(sizeof(struct am65_cpsw_ndev_priv),
+ AM65_CPSW_MAX_QUEUES,
+ AM65_CPSW_MAX_QUEUES);
if (!port->ndev) {
dev_err(dev, "error allocating slave net_device %u\n",
port->port_id);
@@ -2858,7 +2857,7 @@ static int am65_cpsw_nuss_init_ndevs(struct am65_cpsw_common *common)
return ret;
}
- return ret;
+ return 0;

This chunk looks unrelated from the actual fix, please do not include in the next revision.

}
static void am65_cpsw_nuss_cleanup_ndev(struct am65_cpsw_common *common)
@@ -2868,8 +2867,12 @@ static void am65_cpsw_nuss_cleanup_ndev(struct am65_cpsw_common *common)
for (i = 0; i < common->port_num; i++) {
port = &common->ports[i];
- if (port->ndev && port->ndev->reg_state == NETREG_REGISTERED)
+ if (!port->ndev)
+ continue;
+ if (port->ndev->reg_state == NETREG_REGISTERED)
unregister_netdev(port->ndev);
+ free_netdev(port->ndev);
+ port->ndev = NULL;
}
}
@@ -3624,6 +3627,7 @@ static int am65_cpsw_nuss_probe(struct platform_device *pdev)
err_free_phylink:
am65_cpsw_nuss_phylink_cleanup(common);
+ am65_cpsw_nuss_cleanup_ndev(common);

The cleanup functions are called in the reverse order in am65_cpsw_nuss_remove(). Skimming over the code the actual order between these 2 does not matter (please double check this statement), but it would be better to be consistent.

Cheers,

Paolo

am65_cpts_release(common->cpts);
err_of_clear:
if (common->mdio_dev)