Re: [PATCH 1/4] radix-tree: add end_index to support ranged iteration

From: Konstantin Khlebnikov
Date: Wed May 21 2014 - 04:21:28 EST

Next message: Aaron Lu: "Re: rmmod thermal, unable to handle kernel NULL pointer dereference"
Previous message: Lee Jones: "[PATCH 1/3] ARM: sti: stih416: Add support for B2020 RevE"
In reply to: Naoya Horiguchi: "[PATCH 1/4] radix-tree: add end_index to support ranged iteration"
Next in thread: Andrew Morton: "Re: [PATCH 0/4] pagecache scanning with /proc/kpagecache"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Wed, May 21, 2014 at 6:26 AM, Naoya Horiguchi
<n-horiguchi@xxxxxxxxxxxxx> wrote:
> It's useful if we can run only over a specific index range of radix trees,
> which this patch does. This patch changes only radix_tree_for_each_slot()
> and radix_tree_for_each_tagged(), because we need it only for them for now.

NAK, I don't see how this is usefull. Main users don't need this.
Barely used argument don't makes complicated macro easier.
radix_tree_next_slot() is perfomance-critical. I'm not sure that
compiler can throw out
your checks if the end is -1, since it stored in structure which is
passed into function.

Just write something like this where needed.

radix_tree_for_each_slot(..) {
if (iter.index > end)
goto out;
<...>
if (iter.index == end)
goto out;
}
out:

Probably this migh be hidden in a macro as well.
There is simple way to abort iterating: set next_index to zero and
break inner loop.

>
> ChangeLog:
> - rebased onto v3.15-rc5, which has e a few new caller of radix_tree_for_each_slot(),
> so apply this change them too.
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/qxl/qxl_ttm.c | 2 +-
> include/linux/radix-tree.h | 27 ++++++++++++++++++++-------
> kernel/irq/irqdomain.c | 2 +-
> lib/radix-tree.c | 8 ++++----
> mm/filemap.c | 8 ++++----
> 5 files changed, 30 insertions(+), 17 deletions(-)
>
> diff --git v3.15-rc5.orig/drivers/gpu/drm/qxl/qxl_ttm.c v3.15-rc5/drivers/gpu/drm/qxl/qxl_ttm.c
> index d52c27527b9a..d807e66fe308 100644
> --- v3.15-rc5.orig/drivers/gpu/drm/qxl/qxl_ttm.c
> +++ v3.15-rc5/drivers/gpu/drm/qxl/qxl_ttm.c
> @@ -398,7 +398,7 @@ static int qxl_sync_obj_wait(void *sync_obj,
> struct radix_tree_iter iter;
> int release_id;
>
> - radix_tree_for_each_slot(slot, &qfence->tree, &iter, 0) {
> + radix_tree_for_each_slot(slot, &qfence->tree, &iter, 0, ~0UL) {
> struct qxl_release *release;
>
> release_id = iter.index;
> diff --git v3.15-rc5.orig/include/linux/radix-tree.h v3.15-rc5/include/linux/radix-tree.h
> index 33170dbd9db4..88258c34371f 100644
> --- v3.15-rc5.orig/include/linux/radix-tree.h
> +++ v3.15-rc5/include/linux/radix-tree.h
> @@ -312,6 +312,7 @@ static inline void radix_tree_preload_end(void)
> * @index: index of current slot
> * @next_index: next-to-last index for this chunk
> * @tags: bit-mask for tag-iterating
> + * @end_index: last index to be scanned
> *
> * This radix tree iterator works in terms of "chunks" of slots. A chunk is a
> * subinterval of slots contained within one radix tree leaf node. It is
> @@ -324,6 +325,7 @@ struct radix_tree_iter {
> unsigned long index;
> unsigned long next_index;
> unsigned long tags;
> + unsigned long end_index;
> };
>
> #define RADIX_TREE_ITER_TAG_MASK 0x00FF /* tag index in lower byte */
> @@ -335,10 +337,12 @@ struct radix_tree_iter {
> *
> * @iter: pointer to iterator state
> * @start: iteration starting index
> + * @end: iteration ending index
> * Returns: NULL
> */
> static __always_inline void **
> -radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
> +radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start,
> + unsigned long end)
> {
> /*
> * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
> @@ -350,6 +354,7 @@ radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
> */
> iter->index = 0;
> iter->next_index = start;
> + iter->end_index = end;
> return NULL;
> }
>
> @@ -399,6 +404,8 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
> iter->tags >>= 1;
> if (likely(iter->tags & 1ul)) {
> iter->index++;
> + if (iter->index > iter->end_index)
> + return NULL;
> return slot + 1;
> }
> if (!(flags & RADIX_TREE_ITER_CONTIG) && likely(iter->tags)) {
> @@ -406,6 +413,8 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
>
> iter->tags >>= offset;
> iter->index += offset + 1;
> + if (iter->index > iter->end_index)
> + return NULL;
> return slot + offset + 1;
> }
> } else {
> @@ -414,6 +423,8 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
> while (size--) {
> slot++;
> iter->index++;
> + if (iter->index > iter->end_index)
> + return NULL;
> if (likely(*slot))
> return slot;
> if (flags & RADIX_TREE_ITER_CONTIG) {
> @@ -438,7 +449,7 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
> * Locks can be released and reacquired between iterations.
> */
> #define radix_tree_for_each_chunk(slot, root, iter, start, flags) \
> - for (slot = radix_tree_iter_init(iter, start) ; \
> + for (slot = radix_tree_iter_init(iter, start, ~0UL) ; \
> (slot = radix_tree_next_chunk(root, iter, flags)) ;)
>
> /**
> @@ -461,11 +472,12 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
> * @root: the struct radix_tree_root pointer
> * @iter: the struct radix_tree_iter pointer
> * @start: iteration starting index
> + * @end: iteration ending index
> *
> * @slot points to radix tree slot, @iter->index contains its index.
> */
> -#define radix_tree_for_each_slot(slot, root, iter, start) \
> - for (slot = radix_tree_iter_init(iter, start) ; \
> +#define radix_tree_for_each_slot(slot, root, iter, start, end) \
> + for (slot = radix_tree_iter_init(iter, start, end) ; \
> slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \
> slot = radix_tree_next_slot(slot, iter, 0))
>
> @@ -480,7 +492,7 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
> * @slot points to radix tree slot, @iter->index contains its index.
> */
> #define radix_tree_for_each_contig(slot, root, iter, start) \
> - for (slot = radix_tree_iter_init(iter, start) ; \
> + for (slot = radix_tree_iter_init(iter, start, ~0UL) ; \
> slot || (slot = radix_tree_next_chunk(root, iter, \
> RADIX_TREE_ITER_CONTIG)) ; \
> slot = radix_tree_next_slot(slot, iter, \
> @@ -493,12 +505,13 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
> * @root: the struct radix_tree_root pointer
> * @iter: the struct radix_tree_iter pointer
> * @start: iteration starting index
> + * @end: iteration ending index
> * @tag: tag index
> *
> * @slot points to radix tree slot, @iter->index contains its index.
> */
> -#define radix_tree_for_each_tagged(slot, root, iter, start, tag) \
> - for (slot = radix_tree_iter_init(iter, start) ; \
> +#define radix_tree_for_each_tagged(slot, root, iter, start, end, tag) \
> + for (slot = radix_tree_iter_init(iter, start, end) ; \
> slot || (slot = radix_tree_next_chunk(root, iter, \
> RADIX_TREE_ITER_TAGGED | tag)) ; \
> slot = radix_tree_next_slot(slot, iter, \
> diff --git v3.15-rc5.orig/kernel/irq/irqdomain.c v3.15-rc5/kernel/irq/irqdomain.c
> index f14033700c25..55fc49b412e1 100644
> --- v3.15-rc5.orig/kernel/irq/irqdomain.c
> +++ v3.15-rc5/kernel/irq/irqdomain.c
> @@ -571,7 +571,7 @@ static int virq_debug_show(struct seq_file *m, void *private)
> mutex_lock(&irq_domain_mutex);
> list_for_each_entry(domain, &irq_domain_list, link) {
> int count = 0;
> - radix_tree_for_each_slot(slot, &domain->revmap_tree, &iter, 0)
> + radix_tree_for_each_slot(slot, &domain->revmap_tree, &iter, 0, ~0UL)
> count++;
> seq_printf(m, "%c%-16s %6u %10u %10u %s\n",
> domain == irq_default_domain ? '*' : ' ', domain->name,
> diff --git v3.15-rc5.orig/lib/radix-tree.c v3.15-rc5/lib/radix-tree.c
> index 9599aa72d7a0..531fba8a81db 100644
> --- v3.15-rc5.orig/lib/radix-tree.c
> +++ v3.15-rc5/lib/radix-tree.c
> @@ -1007,7 +1007,7 @@ radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
> if (unlikely(!max_items))
> return 0;
>
> - radix_tree_for_each_slot(slot, root, &iter, first_index) {
> + radix_tree_for_each_slot(slot, root, &iter, first_index, ~0UL) {
> results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
> if (!results[ret])
> continue;
> @@ -1049,7 +1049,7 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root,
> if (unlikely(!max_items))
> return 0;
>
> - radix_tree_for_each_slot(slot, root, &iter, first_index) {
> + radix_tree_for_each_slot(slot, root, &iter, first_index, ~0UL) {
> results[ret] = slot;
> if (indices)
> indices[ret] = iter.index;
> @@ -1086,7 +1086,7 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
> if (unlikely(!max_items))
> return 0;
>
> - radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
> + radix_tree_for_each_tagged(slot, root, &iter, first_index, ~0UL, tag) {
> results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
> if (!results[ret])
> continue;
> @@ -1123,7 +1123,7 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
> if (unlikely(!max_items))
> return 0;
>
> - radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
> + radix_tree_for_each_tagged(slot, root, &iter, first_index, ~0UL, tag) {
> results[ret] = slot;
> if (++ret == max_items)
> break;
> diff --git v3.15-rc5.orig/mm/filemap.c v3.15-rc5/mm/filemap.c
> index 000a220e2a41..d684e4cffe96 100644
> --- v3.15-rc5.orig/mm/filemap.c
> +++ v3.15-rc5/mm/filemap.c
> @@ -1118,7 +1118,7 @@ unsigned find_get_entries(struct address_space *mapping,
>
> rcu_read_lock();
> restart:
> - radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
> + radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start, ~0UL) {
> struct page *page;
> repeat:
> page = radix_tree_deref_slot(slot);
> @@ -1180,7 +1180,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
>
> rcu_read_lock();
> restart:
> - radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
> + radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start, ~0UL) {
> struct page *page;
> repeat:
> page = radix_tree_deref_slot(slot);
> @@ -1324,7 +1324,7 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
> rcu_read_lock();
> restart:
> radix_tree_for_each_tagged(slot, &mapping->page_tree,
> - &iter, *index, tag) {
> + &iter, *index, ~0UL, tag) {
> struct page *page;
> repeat:
> page = radix_tree_deref_slot(slot);
> @@ -2023,7 +2023,7 @@ void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
> pte_t *pte;
>
> rcu_read_lock();
> - radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff) {
> + radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff, ~0UL) {
> if (iter.index > vmf->max_pgoff)
> break;
> repeat:
> --
> 1.9.0
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Aaron Lu: "Re: rmmod thermal, unable to handle kernel NULL pointer dereference"
Previous message: Lee Jones: "[PATCH 1/3] ARM: sti: stih416: Add support for B2020 RevE"
In reply to: Naoya Horiguchi: "[PATCH 1/4] radix-tree: add end_index to support ranged iteration"
Next in thread: Andrew Morton: "Re: [PATCH 0/4] pagecache scanning with /proc/kpagecache"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]