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; > } >
