linux-kernel - Re: [PATCH v2 02/14] atm/nicstar: don't use idr_remove

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Date:	Mon, 4 Feb 2013 13:10:34 -0500
From:	chas williams - CONTRACTOR <chas@....nrl.navy.mil>
To:	Tejun Heo <tj@...nel.org>
Cc:	akpm@...ux-foundation.org, rusty@...tcorp.com.au,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 02/14] atm/nicstar: don't use idr_remove_all()

On Mon, 4 Feb 2013 09:52:10 -0800
Tejun Heo <tj@...nel.org> wrote:

> Subject: atm/nicstar: convert to idr_alloc()
> 
> Convert to the much saner new idr interface.  The existing code looks
> buggy to me - ID 0 is treated as no-ID but allocation specifies 0 as
> lower limit and there's no error handling after partial success.  This
> conversion keeps the bugs unchanged.
> 
> Only compile tested.
> 
> v2: id1 and id2 are now directly used for -errno return and thus
>     should be signed.  Make them int instead of u32.  This was spotted
>     by kbuild test robot.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Acked-by: Chas Williams <chas@....nrl.navy.mil>
> Reported-by: kbuild test robot <fengguang.wu@...el.com>
> Cc: netdev@...r.kernel.org
> ---
>  drivers/atm/nicstar.c |   29 +++++++++++++----------------
>  1 file changed, 13 insertions(+), 16 deletions(-)
> 
> --- a/drivers/atm/nicstar.c
> +++ b/drivers/atm/nicstar.c
> @@ -949,7 +949,7 @@ static void free_scq(ns_dev *card, scq_i
>  static void push_rxbufs(ns_dev * card, struct sk_buff *skb)
>  {
>  	struct sk_buff *handle1, *handle2;
> -	u32 id1 = 0, id2 = 0;
> +	int id1 = 0, id2 = 0;
>  	u32 addr1, addr2;
>  	u32 stat;
>  	unsigned long flags;
> @@ -1026,24 +1026,21 @@ static void push_rxbufs(ns_dev * card, s
>  				card->lbfqc += 2;
>  		}
>  
> -		do {
> -			if (!idr_pre_get(&card->idr, GFP_ATOMIC)) {
> -				printk(KERN_ERR
> -				       "nicstar%d: no free memory for idr\n",
> -				       card->index);
> +		if (id1 < 0) {

you assign id1 to 0, so this never happens i think.  i don't think the
reason to preassign id1/id2 exists anymore once the do loop is removed.

> +			id1 = idr_alloc(&card->idr, handle1, 0, 0, GFP_ATOMIC);
> +			if (id1 < 0) {
> +				err = id1;

you dont need to assign err since it isn't returned.

>  				goto out;
>  			}
> +		}
>  
> -			if (!id1)
> -				err = idr_get_new_above(&card->idr, handle1, 0, &id1);
> -
> -			if (!id2 && err == 0)
> -				err = idr_get_new_above(&card->idr, handle2, 0, &id2);
> -
> -		} while (err == -EAGAIN);
> -
> -		if (err)
> -			goto out;
> +		if (id2 < 0) {

same as above.

> +			id2 = idr_alloc(&card->idr, handle2, 0, 0, GFP_ATOMIC);
> +			if (id2 < 0) {
> +				err = id2;
> +				goto out;
> +			}
> +		}
>  
>  		spin_lock_irqsave(&card->res_lock, flags);
>  		while (CMD_BUSY(card)) ;
--
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