linux-kernel - Re: devm

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Date:	Tue, 27 Dec 2011 11:48:18 +0900
From:	Adam Jiang <jiang.adam@...il.com>
To:	kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: devm_kfree

2011/12/26 Julia Lawall <julia.lawall@...6.fr>:
> Is it reasonable to use devm_kfree in a probe function that fails or a
> remove function that succeeds?

I cannot catch your question. If the memory is allocated by
devm_kzalloc(), it is not necessary to release with devm_kfree() at
all. It would be release once the driver was detached or destroyed.

>
> Examples from drivers/watchdog/shwdt.c:
>
> sh_wdt_probe:
>
>        ...
>  out_unreg:
>        unregister_reboot_notifier(&sh_wdt_notifier);
>  out_unmap:
> -       devm_iounmap(&pdev->dev, wdt->base);
>  out_err:
> -       devm_kfree(&pdev->dev, wdt);

It is necessary?

>  out_release:
> -       devm_release_mem_region(&pdev->dev, res->start, resource_size(res));

It is necessary?

>
>        return rc;
>  }
>
>
> sh_wdt_remove:
>
>        ...
>        unregister_reboot_notifier(&sh_wdt_notifier);
>        devm_release_mem_region(&pdev->dev, res->start, resource_size(res));
>        devm_iounmap(&pdev->dev, wdt->base);
>        devm_kfree(&pdev->dev, wdt);

These lines should be deleted if the driver has detached.

>
>        return 0;
> }
>
>
> On the other hand, perhaps devm_kfree is needed in probe function that
> succeeds, eg in drivers/input/keyboard/samsung-keypad.c:
>
>        if (pdev->dev.of_node) {
>                devm_kfree(&pdev->dev, (void *)pdata->keymap_data->keymap);
>                devm_kfree(&pdev->dev, (void *)pdata->keymap_data);
>                devm_kfree(&pdev->dev, (void *)pdata);
>        }
>        return 0;
>
> julia
> --
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