linux-kernel - Re: [PATCH for-next] RDMA/core: Remove unnecessary statements

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Message-ID: <YhfZbgaz1Hec8xNG@unreal>
Date:   Thu, 24 Feb 2022 21:15:58 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Yajun Deng <yajun.deng@...ux.dev>
Cc:     jgg@...dia.com, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH for-next] RDMA/core: Remove unnecessary statements

On Wed, Feb 23, 2022 at 03:49:01PM +0800, Yajun Deng wrote:
> The rdma_zalloc_drv_obj() in __ib_alloc_pd() would zero pd, it unnecessary
> add NULL to the object in struct pd.
> 
> The uverbs_free_pd() already return busy if pd->usecnt is true, there is
> no need to add a warning.
> 
> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
> ---
>  drivers/infiniband/core/verbs.c | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
> index e821dc94a43e..03bc9d34c13d 100644
> --- a/drivers/infiniband/core/verbs.c
> +++ b/drivers/infiniband/core/verbs.c
> @@ -268,8 +268,6 @@ struct ib_pd *__ib_alloc_pd(struct ib_device *device, unsigned int flags,
>  		return ERR_PTR(-ENOMEM);
>  
>  	pd->device = device;
> -	pd->uobject = NULL;
> -	pd->__internal_mr = NULL;
>  	atomic_set(&pd->usecnt, 0);
^^^^^^^^ this line should be removed too.

>  	pd->flags = flags;
>  
> @@ -341,11 +339,6 @@ int ib_dealloc_pd_user(struct ib_pd *pd, struct ib_udata *udata)
>  		pd->__internal_mr = NULL;
>  	}
>  
> -	/* uverbs manipulates usecnt with proper locking, while the kabi
> -	 * requires the caller to guarantee we can't race here.
> -	 */
> -	WARN_ON(atomic_read(&pd->usecnt));
> -

ib_dealloc_pd_user() is called not only in uverbs_free_pd(), but in ib_dealloc_pd() too.
So commit message is not really correct.

Of course, ib_dealloc_pd() is kernel verb and doesn't use ->usecnt at all.

Thanks,
Reviewed-by: Leon Romanovsky <leonro@...dia.com>