Re: [PATCH 2/2] xen/grant: introduce func gnttab_unmap_refs_async_wait_completion()

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Mar 26, 2015 at 08:16:01PM +0800, Bob Liu wrote:
> There are several place using gnttab async unmap and wait for
> completion, so move the common code to a function
> gnttab_unmap_refs_async_wait_completion().
> 
> Signed-off-by: Bob Liu <bob.liu@oracle.com>

Jens, and would you be OK if this patch went through the Xen tree?

Thanks.
> ---
>  drivers/block/xen-blkback/blkback.c | 31 +++----------------------------
>  drivers/xen/gntdev.c                | 28 +++-------------------------
>  drivers/xen/grant-table.c           | 29 +++++++++++++++++++++++++++++
>  include/xen/grant_table.h           |  1 +
>  4 files changed, 36 insertions(+), 53 deletions(-)
> 
> diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
> index f59d7c3..0c8da82 100644
> --- a/drivers/block/xen-blkback/blkback.c
> +++ b/drivers/block/xen-blkback/blkback.c
> @@ -263,17 +263,6 @@ static void put_persistent_gnt(struct xen_blkif *blkif,
>  	atomic_dec(&blkif->persistent_gnt_in_use);
>  }
>  
> -static void free_persistent_gnts_unmap_callback(int result,
> -						struct gntab_unmap_queue_data *data)
> -{
> -	struct completion *c = data->data;
> -
> -	/* BUG_ON used to reproduce existing behaviour,
> -	   but is this the best way to deal with this? */
> -	BUG_ON(result);
> -	complete(c);
> -}
> -
>  static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
>                                   unsigned int num)
>  {
> @@ -283,12 +272,7 @@ static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
>  	struct rb_node *n;
>  	int segs_to_unmap = 0;
>  	struct gntab_unmap_queue_data unmap_data;
> -	struct completion unmap_completion;
> -
> -	init_completion(&unmap_completion);
>  
> -	unmap_data.data = &unmap_completion;
> -	unmap_data.done = &free_persistent_gnts_unmap_callback;
>  	unmap_data.pages = pages;
>  	unmap_data.unmap_ops = unmap;
>  	unmap_data.kunmap_ops = NULL;
> @@ -308,8 +292,7 @@ static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
>  			!rb_next(&persistent_gnt->node)) {
>  
>  			unmap_data.count = segs_to_unmap;
> -			gnttab_unmap_refs_async(&unmap_data);
> -			wait_for_completion(&unmap_completion);
> +			BUG_ON(gnttab_unmap_refs_async_wait_completion(&unmap_data));
>  
>  			put_free_pages(blkif, pages, segs_to_unmap);
>  			segs_to_unmap = 0;
> @@ -330,12 +313,7 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
>  	int segs_to_unmap = 0;
>  	struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
>  	struct gntab_unmap_queue_data unmap_data;
> -	struct completion unmap_completion;
>  
> -	init_completion(&unmap_completion);
> -
> -	unmap_data.data = &unmap_completion;
> -	unmap_data.done = &free_persistent_gnts_unmap_callback;
>  	unmap_data.pages = pages;
>  	unmap_data.unmap_ops = unmap;
>  	unmap_data.kunmap_ops = NULL;
> @@ -355,9 +333,7 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
>  
>  		if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
>  			unmap_data.count = segs_to_unmap;
> -			gnttab_unmap_refs_async(&unmap_data);
> -			wait_for_completion(&unmap_completion);
> -
> +			BUG_ON(gnttab_unmap_refs_async_wait_completion(&unmap_data));
>  			put_free_pages(blkif, pages, segs_to_unmap);
>  			segs_to_unmap = 0;
>  		}
> @@ -365,8 +341,7 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
>  	}
>  	if (segs_to_unmap > 0) {
>  		unmap_data.count = segs_to_unmap;
> -		gnttab_unmap_refs_async(&unmap_data);
> -		wait_for_completion(&unmap_completion);
> +		BUG_ON(gnttab_unmap_refs_async_wait_completion(&unmap_data));
>  		put_free_pages(blkif, pages, segs_to_unmap);
>  	}
>  }
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index d5bb1a3..7a88524 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -327,30 +327,10 @@ static int map_grant_pages(struct grant_map *map)
>  	return err;
>  }
>  
> -struct unmap_grant_pages_callback_data
> -{
> -	struct completion completion;
> -	int result;
> -};
> -
> -static void unmap_grant_callback(int result,
> -				 struct gntab_unmap_queue_data *data)
> -{
> -	struct unmap_grant_pages_callback_data* d = data->data;
> -
> -	d->result = result;
> -	complete(&d->completion);
> -}
> -
>  static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
>  {
>  	int i, err = 0;
>  	struct gntab_unmap_queue_data unmap_data;
> -	struct unmap_grant_pages_callback_data data;
> -
> -	init_completion(&data.completion);
> -	unmap_data.data = &data;
> -	unmap_data.done= &unmap_grant_callback;
>  
>  	if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
>  		int pgno = (map->notify.addr >> PAGE_SHIFT);
> @@ -367,11 +347,9 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
>  	unmap_data.pages = map->pages + offset;
>  	unmap_data.count = pages;
>  
> -	gnttab_unmap_refs_async(&unmap_data);
> -
> -	wait_for_completion(&data.completion);
> -	if (data.result)
> -		return data.result;
> +	err = gnttab_unmap_refs_async_wait_completion(&unmap_data);
> +	if (err)
> +		return err;
>  
>  	for (i = 0; i < pages; i++) {
>  		if (map->unmap_ops[offset+i].status)
> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> index 17972fb..1dce9bc 100644
> --- a/drivers/xen/grant-table.c
> +++ b/drivers/xen/grant-table.c
> @@ -123,6 +123,12 @@ struct gnttab_ops {
>  	int (*query_foreign_access)(grant_ref_t ref);
>  };
>  
> +struct unmap_refs_async_callback_data
> +{
> +	struct completion completion;
> +	int result;
> +};
> +
>  static struct gnttab_ops *gnttab_interface;
>  
>  static int grant_table_version;
> @@ -863,6 +869,29 @@ void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
>  }
>  EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
>  
> +static void unmap_refs_async_callback(int result,
> +		struct gntab_unmap_queue_data *data)
> +{
> +	struct unmap_refs_async_callback_data* d = data->data;
> +
> +	d->result = result;
> +	complete(&d->completion);
> +}
> +
> +int gnttab_unmap_refs_async_wait_completion(struct gntab_unmap_queue_data* item)
> +{
> +	struct unmap_refs_async_callback_data data;
> +
> +	init_completion(&data.completion);
> +	item->data = &data;
> +	item->done= &unmap_refs_async_callback;
> +	gnttab_unmap_refs_async(item);
> +	wait_for_completion(&data.completion);
> +
> +	return data.result;
> +}
> +EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async_wait_completion);
> +
>  static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
>  {
>  	int rc;
> diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
> index 143ca5f..46bad05 100644
> --- a/include/xen/grant_table.h
> +++ b/include/xen/grant_table.h
> @@ -191,6 +191,7 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
>  		      struct gnttab_unmap_grant_ref *kunmap_ops,
>  		      struct page **pages, unsigned int count);
>  void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
> +int gnttab_unmap_refs_async_wait_completion(struct gntab_unmap_queue_data* item);
>  
>  
>  /* Perform a batch of grant map/copy operations. Retry every batch slot
> -- 
> 1.8.3.1
>