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Message-ID: <e8cf4f85-b05a-4a7a-ae13-406792be1bbe@kernel.org>
Date: Fri, 17 Nov 2023 11:51:56 +0200
From: Roger Quadros <rogerq@...nel.org>
To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc: Siddharth Vadapalli <s-vadapalli@...com>,
Dan Carpenter <dan.carpenter@...aro.org>, netdev@...r.kernel.org,
kernel@...gutronix.de
Subject: Re: [PATCH 1/7] net: ethernet: ti: am65-cpsw: Don't error out in
.remove()
On 17/11/2023 11:16, Uwe Kleine-König wrote:
> 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);
Unrelated to this patch but I see pm_runtime_resume_and_get()
used at multiple places in this driver.
Would it be wise to replace them all with pm_runtime_get_sync()?
> 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);
--
cheers,
-roger
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