Re: [PATCH] bsg: update bsg_device_list to utilize static hash table implementation.

[Tim Hansen <devtimhansen@gmail.com>]

Mon, Oct 02, 2017 at 12:10:01PM -0400, Tim Hansen wrote:
> Updates bsg_device_list to utilize static hashtable implementation.
> 
> This is done in an effort to standarize the hashtables used across the
> kernel.
> 
> Signed-off-by: Tim Hansen <devtimhansen@gmail.com>
> ---
>  block/bsg.c | 20 ++++++--------------
>  1 file changed, 6 insertions(+), 14 deletions(-)
> 
> diff --git a/block/bsg.c b/block/bsg.c
> index ee1335c68de7..ecb93d733b56 100644
> --- a/block/bsg.c
> +++ b/block/bsg.c
> @@ -66,8 +66,8 @@ enum {
>  static DEFINE_MUTEX(bsg_mutex);
>  static DEFINE_IDR(bsg_minor_idr);
>  
> -#define BSG_LIST_ARRAY_SIZE	8
> -static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
> +#define BSG_HASHTABLE_BIT_SIZE		3
> +static DEFINE_HASHTABLE(bsg_device_list, BSG_HASHTABLE_BIT_SIZE);
>  
>  static struct class *bsg_class;
>  static int bsg_major;
> @@ -130,11 +130,6 @@ static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
>  	return bc;
>  }
>  
> -static inline struct hlist_head *bsg_dev_idx_hash(int index)
> -{
> -	return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
> -}
> -
>  static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
>  				struct sg_io_v4 *hdr, struct bsg_device *bd,
>  				fmode_t has_write_perm)
> @@ -716,7 +711,7 @@ static int bsg_put_device(struct bsg_device *bd)
>  		goto out;
>  	}
>  
> -	hlist_del(&bd->dev_list);
> +	hash_del(&bd->dev_list);
>  	mutex_unlock(&bsg_mutex);
>  
>  	dprintk("%s: tearing down\n", bd->name);
> @@ -770,7 +765,7 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
>  
>  	atomic_set(&bd->ref_count, 1);
>  	mutex_lock(&bsg_mutex);
> -	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
> +	hash_add(bsg_device_list, &bd->dev_list, iminor(inode));
>  
>  	strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
>  	dprintk("bound to <%s>, max queue %d\n",
> @@ -786,7 +781,7 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
>  
>  	mutex_lock(&bsg_mutex);
>  
> -	hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
> +	hash_for_each_possible(bsg_device_list, bd, dev_list, minor) {
>  		if (bd->queue == q) {
>  			atomic_inc(&bd->ref_count);
>  			goto found;
> @@ -1042,7 +1037,7 @@ static char *bsg_devnode(struct device *dev, umode_t *mode)
>  
>  static int __init bsg_init(void)
>  {
> -	int ret, i;
> +	int ret;
>  	dev_t devid;
>  
>  	bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
> @@ -1052,9 +1047,6 @@ static int __init bsg_init(void)
>  		return -ENOMEM;
>  	}
>  
> -	for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
> -		INIT_HLIST_HEAD(&bsg_device_list[i]);
> -
>  	bsg_class = class_create(THIS_MODULE, "bsg");
>  	if (IS_ERR(bsg_class)) {
>  		ret = PTR_ERR(bsg_class);
> -- 
> 2.14.2

Pinging folks again kindly for review of this patch.

Thank you