When addr is out of the range of the whole rb_tree, pprev will points to
the right-most node. rb_tree facility already provides a helper
function, rb_last, to do this task. We can leverage this instead of
re-implement it.
This patch refines find_vma_prev with rb_last to make it a little nicer
to read.
Signed-off-by: Wei Yang <[email protected]>
---
v2: leverage rb_last
---
mm/mmap.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index 7e8c3e8ae75f..f7ed0afb994c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2270,12 +2270,9 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
if (vma) {
*pprev = vma->vm_prev;
} else {
- struct rb_node *rb_node = mm->mm_rb.rb_node;
- *pprev = NULL;
- while (rb_node) {
- *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
- rb_node = rb_node->rb_right;
- }
+ struct rb_node *rb_node = rb_last(&mm->mm_rb);
+ *pprev = !rb_node ? NULL :
+ rb_entry(rb_node, struct vm_area_struct, vm_rb);
}
return vma;
}
--
2.17.1
On 8/9/19 2:19 AM, Wei Yang wrote:
> When addr is out of the range of the whole rb_tree, pprev will points to
> the right-most node. rb_tree facility already provides a helper
> function, rb_last, to do this task. We can leverage this instead of
> re-implement it.
>
> This patch refines find_vma_prev with rb_last to make it a little nicer
> to read.
>
> Signed-off-by: Wei Yang <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Nit below:
> ---
> v2: leverage rb_last
> ---
> mm/mmap.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 7e8c3e8ae75f..f7ed0afb994c 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2270,12 +2270,9 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
> if (vma) {
> *pprev = vma->vm_prev;
> } else {
> - struct rb_node *rb_node = mm->mm_rb.rb_node;
> - *pprev = NULL;
> - while (rb_node) {
> - *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
> - rb_node = rb_node->rb_right;
> - }
> + struct rb_node *rb_node = rb_last(&mm->mm_rb);
> + *pprev = !rb_node ? NULL :
> + rb_entry(rb_node, struct vm_area_struct, vm_rb);
It's perhaps more common to write it like:
*pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
> }
> return vma;
> }
>
On Fri, Aug 09, 2019 at 10:03:20AM +0200, Vlastimil Babka wrote:
>On 8/9/19 2:19 AM, Wei Yang wrote:
>> When addr is out of the range of the whole rb_tree, pprev will points to
>> the right-most node. rb_tree facility already provides a helper
>> function, rb_last, to do this task. We can leverage this instead of
>> re-implement it.
>>
>> This patch refines find_vma_prev with rb_last to make it a little nicer
>> to read.
>>
>> Signed-off-by: Wei Yang <[email protected]>
>
>Acked-by: Vlastimil Babka <[email protected]>
>
>Nit below:
>
>> ---
>> v2: leverage rb_last
>> ---
>> mm/mmap.c | 9 +++------
>> 1 file changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/mmap.c b/mm/mmap.c
>> index 7e8c3e8ae75f..f7ed0afb994c 100644
>> --- a/mm/mmap.c
>> +++ b/mm/mmap.c
>> @@ -2270,12 +2270,9 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
>> if (vma) {
>> *pprev = vma->vm_prev;
>> } else {
>> - struct rb_node *rb_node = mm->mm_rb.rb_node;
>> - *pprev = NULL;
>> - while (rb_node) {
>> - *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
>> - rb_node = rb_node->rb_right;
>> - }
>> + struct rb_node *rb_node = rb_last(&mm->mm_rb);
>> + *pprev = !rb_node ? NULL :
>> + rb_entry(rb_node, struct vm_area_struct, vm_rb);
>
>It's perhaps more common to write it like:
>*pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
>
Do you prefer me to send v3 with this updated?
>> }
>> return vma;
>> }
>>
--
Wei Yang
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