linux-kernel - Re: [PATCH 1/5] SCSI: sd: simplify ida usage

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Date:	Fri, 02 Oct 2015 12:15:04 +0200
From:	Johannes Thumshirn <jthumshirn@...e.de>
To:	Lee Duncan <lduncan@...e.com>
Cc:	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Tejun Heo <tj@...nel.org>, Hannes Reinecke <hare@...e.com>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 1/5] SCSI: sd: simplify ida usage

Lee Duncan <lduncan@...e.com> writes:

> Simplify ida index allocation and removal by
> using the ida_simple_* helper functions.
>
> Signed-off-by: Lee Duncan <lduncan@...e.com>
> ---
>  drivers/scsi/sd.c | 22 +++++-----------------
>  1 file changed, 5 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 3b2fcb4fada0..3d77ac8f0d4c 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -118,7 +118,6 @@ static void scsi_disk_release(struct device *cdev);
>  static void sd_print_sense_hdr(struct scsi_disk *, struct scsi_sense_hdr *);
>  static void sd_print_result(const struct scsi_disk *, const char *, int);
>  
> -static DEFINE_SPINLOCK(sd_index_lock);
>  static DEFINE_IDA(sd_index_ida);
>  
>  /* This semaphore is used to mediate the 0->1 reference get in the
> @@ -2948,19 +2947,12 @@ static int sd_probe(struct device *dev)
>  	if (!gd)
>  		goto out_free;
>  
> -	do {
> -		if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
> -			goto out_put;
> -
> -		spin_lock(&sd_index_lock);
> -		error = ida_get_new(&sd_index_ida, &index);
> -		spin_unlock(&sd_index_lock);
> -	} while (error == -EAGAIN);
> -
> -	if (error) {
> +	error = ida_simple_get(&sd_index_ida, 0, 0, GFP_KERNEL);
> +	if (error < 0) {
>  		sdev_printk(KERN_WARNING, sdp, "sd_probe: memory exhausted.\n");
>  		goto out_put;
>  	}
> +	index = error;
>  
>  	error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN);
>  	if (error) {
> @@ -3001,9 +2993,7 @@ static int sd_probe(struct device *dev)
>  	return 0;
>  
>   out_free_index:
> -	spin_lock(&sd_index_lock);
> -	ida_remove(&sd_index_ida, index);
> -	spin_unlock(&sd_index_lock);
> +	ida_simple_remove(&sd_index_ida, index);
>   out_put:
>  	put_disk(gd);
>   out_free:
> @@ -3064,9 +3054,7 @@ static void scsi_disk_release(struct device *dev)
>  	struct scsi_disk *sdkp = to_scsi_disk(dev);
>  	struct gendisk *disk = sdkp->disk;
>  	
> -	spin_lock(&sd_index_lock);
> -	ida_remove(&sd_index_ida, sdkp->index);
> -	spin_unlock(&sd_index_lock);
> +	ida_simple_remove(&sd_index_ida, sdkp->index);
>  
>  	blk_integrity_unregister(disk);
>  	disk->private_data = NULL;

Reviewed-by: Johannes Thumshirn <jthumshirn@...e.de>

-- 
Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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