linux-kernel - Re: [PATCH] RDMA/hfi: add a judgment on the availability of cpumask

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Date:   Tue, 4 Apr 2023 09:05:22 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     xiaolinkui <xiaolinkui@....com>
Cc:     dennis.dalessandro@...nelisnetworks.com, jgg@...pe.ca,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linkui Xiao <xiaolinkui@...inos.cn>
Subject: Re: [PATCH] RDMA/hfi: add a judgment on the availability of cpumask

On Tue, Apr 04, 2023 at 11:05:25AM +0800, xiaolinkui wrote:
> From: Linkui Xiao <xiaolinkui@...inos.cn>
> 
> When CONFIG_CPUMASK_OFFSTACK is n, cpumask may fail to allocate, cpumask may
> be NULL, and performing a bitmap operation on cpumask may cause problems at
> this time.
> 
> Of course, this is a unlikely event.
> 
> Signed-off-by: Linkui Xiao <xiaolinkui@...inos.cn>
> ---
>  drivers/infiniband/hw/hfi1/affinity.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/hfi1/affinity.c b/drivers/infiniband/hw/hfi1/affinity.c
> index 77ee77d4000f..3caa861f4d1d 100644
> --- a/drivers/infiniband/hw/hfi1/affinity.c
> +++ b/drivers/infiniband/hw/hfi1/affinity.c
> @@ -1047,16 +1047,16 @@ int hfi1_get_proc_affinity(int node)
>  	 */
>  
>  	ret = zalloc_cpumask_var(&diff, GFP_KERNEL);
> -	if (!ret)
> +	if (!ret || unlikely(!diff))

Why do you think that check of "ret" is not enough?
"ret" will be false if diff == NULL.

Thanks