Re: [PATCHv3] atm: nicstar: simplify allocation

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

On 3/27/26 13:24, Rosen Penev wrote:
> Use a flexible array member with kzalloc_flex to combine allocations
> into one.
> 
> Add __counted_by for extra runtime analysis. 

Move counting variable
> assignment to right after allocation as required by __counted_by.

This is misinformation and should be phrased differently[1]

-Gustavo

[1] https://lore.kernel.org/linux-hardening/37378f49-437f-438b-ad6c-d60480feb306@embeddedor.com/

> 
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>   v3: reduce to 80 columns
>   v2: use kzalloc_flex
>   drivers/atm/nicstar.c | 18 ++++++------------
>   drivers/atm/nicstar.h |  5 +++--
>   2 files changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/atm/nicstar.c b/drivers/atm/nicstar.c
> index 24e51343df15..c0bed85daf96 100644
> --- a/drivers/atm/nicstar.c
> +++ b/drivers/atm/nicstar.c
> @@ -867,23 +867,18 @@ static scq_info *get_scq(ns_dev *card, int size, u32 scd)
>   	if (size != VBR_SCQSIZE && size != CBR_SCQSIZE)
>   		return NULL;
> 
> -	scq = kmalloc_obj(*scq);
> +	scq = kzalloc_flex(*scq, skb, size / NS_SCQE_SIZE);
>   	if (!scq)
>   		return NULL;
> -        scq->org = dma_alloc_coherent(&card->pcidev->dev,
> -				      2 * size,  &scq->dma, GFP_KERNEL);
> +
> +	scq->num_entries = size / NS_SCQE_SIZE;
> +
> +	scq->org = dma_alloc_coherent(&card->pcidev->dev, 2 * size, &scq->dma,
> +				      GFP_KERNEL);
>   	if (!scq->org) {
>   		kfree(scq);
>   		return NULL;
>   	}
> -	scq->skb = kzalloc_objs(*scq->skb, size / NS_SCQE_SIZE);
> -	if (!scq->skb) {
> -		dma_free_coherent(&card->pcidev->dev,
> -				  2 * size, scq->org, scq->dma);
> -		kfree(scq);
> -		return NULL;
> -	}
> -	scq->num_entries = size / NS_SCQE_SIZE;
>   	scq->base = PTR_ALIGN(scq->org, size);
>   	scq->next = scq->base;
>   	scq->last = scq->base + (scq->num_entries - 1);
> @@ -928,7 +923,6 @@ static void free_scq(ns_dev *card, scq_info *scq, struct atm_vcc *vcc)
>   				}
>   			}
>   	}
> -	kfree(scq->skb);
>   	dma_free_coherent(&card->pcidev->dev,
>   			  2 * (scq->num_entries == VBR_SCQ_NUM_ENTRIES ?
>   			       VBR_SCQSIZE : CBR_SCQSIZE),
> diff --git a/drivers/atm/nicstar.h b/drivers/atm/nicstar.h
> index 1b7f1dfc1735..76635d46016e 100644
> --- a/drivers/atm/nicstar.h
> +++ b/drivers/atm/nicstar.h
> @@ -667,14 +667,15 @@ typedef struct scq_info {
>   	ns_scqe *next;
>   	volatile ns_scqe *tail;	/* Not related to the nicstar register */
>   	unsigned num_entries;
> -	struct sk_buff **skb;	/* Pointer to an array of pointers
> -				   to the sk_buffs used for tx */
>   	u32 scd;		/* SRAM address of the corresponding
>   				   SCD */
>   	int tbd_count;		/* Only meaningful on variable rate */
>   	wait_queue_head_t scqfull_waitq;
>   	volatile char full;	/* SCQ full indicator */
>   	spinlock_t lock;	/* SCQ spinlock */
> +	struct sk_buff *skb[] __counted_by(num_entries);
> +	/* Pointer to an array of pointers
> +	   to the sk_buffs used for tx */
>   } scq_info;
> 
>   typedef struct rsq_info {
> --
> 2.53.0
> 
>