Re: Badness in as_insert_request at drivers/block/as-iosched.c:1519

[Mark v Wolher <trilight@ns666.com>]

Jens Axboe wrote:
> On Sat, Jan 07 2006, Mark v Wolher wrote:
> 
>>Jens Axboe wrote:
>>
>>>On Sat, Jan 07 2006, Mark v Wolher wrote:
>>>
>>>
>>>>Hiya all,
>>>>
>>>>I was just playing a cd as usual and i noticed suddenly the errors
>>>>below, they repeated like 8 times.
>>>>
>>>>kernel: 2.6.14.5
>>>
>>>
>>>Should be fixed in newer 2.6.14.x, and in 2.6.15.
>>>
>>
>>Looks like it isn't :( , well in 2.6.14.5
> 
> 
> Oh, indeed. 2.6.15 has it fixed though. For 2.6.14.5 you have two
> choices:
> 
> 1) Delete the warning from as-iosched.c. It's harmless, it doesn't
>    indicate a bug in this case.
> 
> 2) Apply this attached patch to prevent cdrom.c from reusing a request
>    when doing single frame cdda dma.
> 
> diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> index 1539603..7540d27 100644
> --- a/drivers/cdrom/cdrom.c
> +++ b/drivers/cdrom/cdrom.c
> @@ -2089,7 +2089,7 @@ static int cdrom_read_cdda_bpc(struct cd
>  			       int lba, int nframes)
>  {
>  	request_queue_t *q = cdi->disk->queue;
> -	struct request *rq;
> +	struct request *rq = NULL;
>  	struct bio *bio;
>  	unsigned int len;
>  	int nr, ret = 0;
> @@ -2097,13 +2097,13 @@ static int cdrom_read_cdda_bpc(struct cd
>  	if (!q)
>  		return -ENXIO;
>  
> -	rq = blk_get_request(q, READ, GFP_KERNEL);
> -	if (!rq)
> -		return -ENOMEM;
> -
>  	cdi->last_sense = 0;
>  
>  	while (nframes) {
> +		rq = blk_get_request(q, READ, GFP_KERNEL);
> +		if (!rq)
> +			return -ENOMEM;
> +
>  		nr = nframes;
>  		if (cdi->cdda_method == CDDA_BPC_SINGLE)
>  			nr = 1;
> @@ -2151,9 +2151,13 @@ static int cdrom_read_cdda_bpc(struct cd
>  		nframes -= nr;
>  		lba += nr;
>  		ubuf += len;
> +		blk_put_request(rq);
> +		rq = NULL;
>  	}
>  
> -	blk_put_request(rq);
> +	if (rq)
> +		blk_put_request(rq);
> +
>  	return ret;
>  }
>  
> 



Ah ok, thanks alot mate ! I think i'll patch it until i switch to 2.6.15.

Thanks again !

Mark
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