On Wed, Jan 08, 2025 at 11:30:49AM +0800, Ma Ke wrote:
> Once device_register() failed, we should call put_device() to
> decrement reference count for cleanup. Or it could cause memory leak.
>
> device_register() includes device_add(). As comment of device_add()
> says, 'if device_add() succeeds, you should call device_del() when you
> want to get rid of it. If device_add() has not succeeded, use only
> put_device() to drop the reference count'.
I reviewed a previous version of this patch, and commented about the
commit message:
The commit message is not quite correct:
"After calling device_register(), the correct way to dispose of the
device is to call put_device() as per the device_register()
documentation rather than kfree()."
Alex Elder also commented about this. Please fix the commit message.
What device_add() doesn't matter, this code isn't calling device_add(),
it's calling device_register(), and the comments against
device_register() should be appearing in the commit message, not
the comments against device_add().
Thanks.
>
> Found by code review.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Ma Ke <make24@xxxxxxxxxxx>
> ---
> Changes in v4:
> - deleted the redundant initialization;
> Changes in v3:
> - modified the patch as suggestions;
> Changes in v2:
> - modified the patch as suggestions.
> ---
> arch/arm/common/locomo.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm/common/locomo.c b/arch/arm/common/locomo.c
> index cb6ef449b987..45106066a17f 100644
> --- a/arch/arm/common/locomo.c
> +++ b/arch/arm/common/locomo.c
> @@ -223,10 +223,8 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info)
> int ret;
>
> dev = kzalloc(sizeof(struct locomo_dev), GFP_KERNEL);
> - if (!dev) {
> - ret = -ENOMEM;
> - goto out;
> - }
> + if (!dev)
> + return -ENOMEM;
>
> /*
> * If the parent device has a DMA mask associated with it,
> @@ -254,10 +252,9 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info)
> NO_IRQ : lchip->irq_base + info->irq[0];
>
> ret = device_register(&dev->dev);
> - if (ret) {
> - out:
> - kfree(dev);
> - }
> + if (ret)
> + put_device(&dev->dev);
> +
> return ret;
> }
>
> --
> 2.25.1
>
>
--
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