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SubjectRe: [PATCH] Remove needless lock and list in vmap
On Wed, Jan 07, 2009 at 02:47:13PM +0900, MinChan Kim wrote:
> Anyone don't use vmap's dirty_list.
> I am not sure this is thing Nick's future work on purpose.
> If it is a dummy, we can remove dirty list and related codes
> to handle list and locking.
>
> Also, In free_vmap_block, we don't have to check empty free_list.
> That's becuase before calling free_vmap_block, vb_free always checks
> empty of vb->free_list.
>
> Now except vb_free, Anywhere don't call free_vmap_block.
> so, we can remove that check and locking.
>
> If it is nick's intention to work in future, please, ignore this patch.

I should add, it isn't really required for -stable.

>
> Signed-off-by: MinChan Kim <minchan.kim@gmail.com>
> ---
> mm/vmalloc.c | 19 ++-----------------
> 1 files changed, 2 insertions(+), 17 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 1ddb77b..1f79883 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -629,10 +629,7 @@ struct vmap_block {
> DECLARE_BITMAP(alloc_map, VMAP_BBMAP_BITS);
> DECLARE_BITMAP(dirty_map, VMAP_BBMAP_BITS);
> union {
> - struct {
> - struct list_head free_list;
> - struct list_head dirty_list;
> - };
> + struct list_head free_list;
> struct rcu_head rcu_head;
> };
> };
> @@ -699,7 +696,6 @@ static struct vmap_block *new_vmap_block(gfp_t gfp_mask)
> bitmap_zero(vb->alloc_map, VMAP_BBMAP_BITS);
> bitmap_zero(vb->dirty_map, VMAP_BBMAP_BITS);
> INIT_LIST_HEAD(&vb->free_list);
> - INIT_LIST_HEAD(&vb->dirty_list);
>
> vb_idx = addr_to_vb_idx(va->va_start);
> spin_lock(&vmap_block_tree_lock);
> @@ -730,13 +726,6 @@ static void free_vmap_block(struct vmap_block *vb)
> struct vmap_block *tmp;
> unsigned long vb_idx;
>
> - spin_lock(&vb->vbq->lock);
> - if (!list_empty(&vb->free_list))
> - list_del(&vb->free_list);
> - if (!list_empty(&vb->dirty_list))
> - list_del(&vb->dirty_list);
> - spin_unlock(&vb->vbq->lock);
> -
> vb_idx = addr_to_vb_idx(vb->va->va_start);
> spin_lock(&vmap_block_tree_lock);
> tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
> @@ -820,11 +809,7 @@ static void vb_free(const void *addr, unsigned long size)
>
> spin_lock(&vb->lock);
> bitmap_allocate_region(vb->dirty_map, offset >> PAGE_SHIFT, order);
> - if (!vb->dirty) {
> - spin_lock(&vb->vbq->lock);
> - list_add(&vb->dirty_list, &vb->vbq->dirty);
> - spin_unlock(&vb->vbq->lock);
> - }
> +
> vb->dirty += 1UL << order;
> if (vb->dirty == VMAP_BBMAP_BITS) {
> BUG_ON(vb->free || !list_empty(&vb->free_list));
> --
> 1.5.4.3


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