netdev - [PATCH 1/7] net: ethernet: ti: am65-cpsw: Don't error out in .remove()

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Date: Fri, 17 Nov 2023 10:16:57 +0100
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: 
Cc: Siddharth Vadapalli <s-vadapalli@...com>,
	Roger Quadros <rogerq@...nel.org>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	netdev@...r.kernel.org,
	kernel@...gutronix.de
Subject: [PATCH 1/7] net: ethernet: ti: am65-cpsw: Don't error out in .remove()

Returning early from .remove() with an error code still results in the
driver unbinding the device. So the driver core ignores the returned error
code and the resources that were not freed are never catched up. In
combination with devm this also often results in use-after-free bugs.

In case of the am65-cpsw-nuss driver there is an error path, but it's never
taken because am65_cpts_resume() never fails (which however might be
another problem). Still make this explicit and drop the early return in
exchange for an error message (that is more useful than the error the
driver core emits when .remove() returns non-zero).

This prepares changing am65_cpsw_nuss_remove() to return void.

Fixes: 93a76530316a ("net: ethernet: ti: introduce am65x/j721e gigabit eth subsystem driver")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 drivers/net/ethernet/ti/am65-cpsw-nuss.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index ece9f8df98ae..960cb3fa0754 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -3007,9 +3007,12 @@ static int am65_cpsw_nuss_remove(struct platform_device *pdev)

 	common = dev_get_drvdata(dev);

-	ret = pm_runtime_resume_and_get(&pdev->dev);
+	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0)
-		return ret;
+		/* am65_cpts_resume() doesn't fail, so handling ret < 0 is only
+		 * for the sake of completeness.
+		 */
+		dev_err(dev, "runtime resume failed (%pe)\n", ERR_PTR(ret));

 	am65_cpsw_unregister_devlink(common);
 	am65_cpsw_unregister_notifiers(common);
-- 
2.42.0