[PATCH net] net: fec: Better handle pm_runtime_get() failing in .remove()

[PATCH net] net: fec: Better handle pm_runtime_get() failing in .remove()

[Uwe Kleine-König]

In the (unlikely) event that pm_runtime_get() (disguised as
pm_runtime_resume_and_get()) fails, the remove callback returned an
error early. The problem with this is that the driver core ignores the
error value and continues removing the device. This results in a
resource leak. Worse the devm allocated resources are freed and so if a
callback of the driver is called later the register mapping is already
gone which probably results in a crash.

Fixes: a31eda65ba21 ("net: fec: fix clock count mis-match")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/net/ethernet/freescale/fec_main.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 42ec6ca3bf03..241df41d500f 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -4478,9 +4478,11 @@ fec_drv_remove(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	int ret;
 
-	ret = pm_runtime_resume_and_get(&pdev->dev);
+	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0)
-		return ret;
+		dev_err(&pdev->dev,
+			"Failed to resume device in remove callback (%pe)\n",
+			ERR_PTR(ret));
 
 	cancel_work_sync(&fep->tx_timeout_work);
 	fec_ptp_stop(pdev);
@@ -4493,8 +4495,13 @@ fec_drv_remove(struct platform_device *pdev)
 		of_phy_deregister_fixed_link(np);
 	of_node_put(fep->phy_node);
 
-	clk_disable_unprepare(fep->clk_ahb);
-	clk_disable_unprepare(fep->clk_ipg);
+	/* After pm_runtime_get_sync() failed, the clks are still off, so skip
+	 * disabling them again.
+	 */
+	if (ret >= 0) {
+		clk_disable_unprepare(fep->clk_ahb);
+		clk_disable_unprepare(fep->clk_ipg);
+	}
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 
base-commit: ac9a78681b921877518763ba0e89202254349d1b
-- 
2.39.2

Re: [PATCH net] net: fec: Better handle pm_runtime_get() failing in .remove()

[Andrew Lunn]

On Wed, May 10, 2023 at 10:00:20PM +0200, Uwe Kleine-König wrote:
> In the (unlikely) event that pm_runtime_get() (disguised as
> pm_runtime_resume_and_get()) fails, the remove callback returned an
> error early. The problem with this is that the driver core ignores the
> error value and continues removing the device. This results in a
> resource leak. Worse the devm allocated resources are freed and so if a
> callback of the driver is called later the register mapping is already
> gone which probably results in a crash.
> 
> Fixes: a31eda65ba21 ("net: fec: fix clock count mis-match")
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH net] net: fec: Better handle pm_runtime_get() failing in .remove()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 10 May 2023 22:00:20 +0200 you wrote:
> In the (unlikely) event that pm_runtime_get() (disguised as
> pm_runtime_resume_and_get()) fails, the remove callback returned an
> error early. The problem with this is that the driver core ignores the
> error value and continues removing the device. This results in a
> resource leak. Worse the devm allocated resources are freed and so if a
> callback of the driver is called later the register mapping is already
> gone which probably results in a crash.
> 
> [...]

Here is the summary with links:
  - [net] net: fec: Better handle pm_runtime_get() failing in .remove()
    https://git.kernel.org/netdev/net/c/f816b9829b19

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html