netdev - [PATCH 3/7] net: ethernet: ti: cpsw-new: Don't error out in .remove()

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Message-ID: <20231117091655.872426-4-u.kleine-koenig@pengutronix.de>
Date: Fri, 17 Nov 2023 10:16:59 +0100
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: 
Cc: Siddharth Vadapalli <s-vadapalli@...com>,
	Ravi Gunasekaran <r-gunasekaran@...com>,
	Roger Quadros <rogerq@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Marek Majtyka <alardam@...il.com>,
	Gerhard Engleder <gerhard@...leder-embedded.com>,
	Rob Herring <robh@...nel.org>,
	Yunsheng Lin <linyunsheng@...wei.com>,
	Ilias Apalodimas <ilias.apalodimas@...aro.org>,
	linux-omap@...r.kernel.org,
	netdev@...r.kernel.org,
	kernel@...gutronix.de
Subject: [PATCH 3/7] net: ethernet: ti: cpsw-new: 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.

If runtime resume fails, it's still important to free all resources, so
don't return with an error code, but emit an error message and continue
freeing acquired stuff.

This prepares changing cpsw_remove() to return void.

Fixes: ed3525eda4c4 ("net: ethernet: ti: introduce cpsw switchdev based driver part 1 - dual-emac")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 drivers/net/ethernet/ti/cpsw_new.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
index 0e4f526b1753..a6ce409f563c 100644
--- a/drivers/net/ethernet/ti/cpsw_new.c
+++ b/drivers/net/ethernet/ti/cpsw_new.c
@@ -2042,16 +2042,24 @@ static int cpsw_remove(struct platform_device *pdev)
 	struct cpsw_common *cpsw = platform_get_drvdata(pdev);
 	int ret;
 
-	ret = pm_runtime_resume_and_get(&pdev->dev);
+	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0)
-		return ret;
+		/* There is no need to do something about that. The important
+		 * thing is to not exit early, but do all cleanup that doesn't
+		 * requrie register access.
+		 */
+		dev_err(&pdev->dev, "runtime resume failed (%pe)\n",
+			ERR_PTR(ret));
 
 	cpsw_unregister_notifiers(cpsw);
 	cpsw_unregister_devlink(cpsw);
 	cpsw_unregister_ports(cpsw);
 
-	cpts_release(cpsw->cpts);
-	cpdma_ctlr_destroy(cpsw->dma);
+	if (ret >= 0) {
+		cpts_release(cpsw->cpts);
+		cpdma_ctlr_destroy(cpsw->dma);
+	}
+
 	cpsw_remove_dt(cpsw);
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
-- 
2.42.0