linux-kernel - Re: [PATCH 2/2] ntb: ntb_transport: Replace GFP_ATOMIC with GFP_KERNEL in ntb_transport_create

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Date:   Mon, 21 May 2018 20:35:03 -0400
From:   Jon Mason <jdmason@...zu.us>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     dave.jiang@...el.com, Allen.Hubbe@....com,
        linux-ntb@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ntb: ntb_transport: Replace GFP_ATOMIC with
 GFP_KERNEL in ntb_transport_create_queue

On Tue, Apr 10, 2018 at 09:17:54PM +0800, Jia-Ju Bai wrote:
> ntb_transport_create_queue() is never called in atomic context.
> 
> ntb_transport_create_queue() is only called by ntb_netdev_probe(),
> which is set as ".probe" in struct ntb_transport_client.
> 
> Despite never getting called from atomic context,
> ntb_transport_create_queue() calls kzalloc_node() with GFP_ATOMIC,
> which does not sleep for allocation.
> GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
> which can sleep and improve the possibility of sucessful allocation.
> 
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>

Both patches have been applied to my ntb-next branch.

Thanks,
Jon

> ---
>  drivers/ntb/ntb_transport.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
> index f58d8e3..2c0c8bc 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -1825,7 +1825,7 @@ struct ntb_transport_qp *
>  		qp->rx_dma_chan ? "DMA" : "CPU");
>  
>  	for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
> -		entry = kzalloc_node(sizeof(*entry), GFP_ATOMIC, node);
> +		entry = kzalloc_node(sizeof(*entry), GFP_KERNEL, node);
>  		if (!entry)
>  			goto err1;
>  
> @@ -1836,7 +1836,7 @@ struct ntb_transport_qp *
>  	qp->rx_alloc_entry = NTB_QP_DEF_NUM_ENTRIES;
>  
>  	for (i = 0; i < qp->tx_max_entry; i++) {
> -		entry = kzalloc_node(sizeof(*entry), GFP_ATOMIC, node);
> +		entry = kzalloc_node(sizeof(*entry), GFP_KERNEL, node);
>  		if (!entry)
>  			goto err2;
>  
> -- 
> 1.9.1
>