On 18.11.19 07:39, linmiaohe wrote:
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
The jump labels try_prev and none are not really needed
in find_mergeable_anon_vma(), eliminate them to improve
readability.
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
-v2:
Fix commit descriptions and further simplify the code
as suggested by David Hildenbrand and John Hubbard.
-v3:
Rewrite patch version info. Don't show this in commit log.
---
mm/mmap.c | 27 +++++++++++++--------------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index 4d4db76a07da..ff02c23fd375 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1276,26 +1276,25 @@ static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_
*/
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
{
- struct anon_vma *anon_vma;
+ struct anon_vma *anon_vma = NULL;
struct vm_area_struct *near;
+ /* Try next first. */
near = vma->vm_next;
- if (!near)
- goto try_prev;
+ if (near) {
+ anon_vma = reusable_anon_vma(near, vma, near);
+ if (anon_vma)
+ return anon_vma;
+ }
I think you can get rid of near completely as well
if (vma->vm_next) {
anon_vma = reusable_anon_vma(near, vma, vma->vm_next);
if (anon_vma)
return anon_vma;
}
...
Apart from that looks good to me.
- anon_vma = reusable_anon_vma(near, vma, near);
- if (anon_vma)
- return anon_vma;
-try_prev:
+ /* Try prev next. */
near = vma->vm_prev;
- if (!near)
- goto none;
+ if (near)
+ anon_vma = reusable_anon_vma(near, near, vma);
- anon_vma = reusable_anon_vma(near, near, vma);
- if (anon_vma)
- return anon_vma;
-none:
/*
+ * We might reach here with anon_vma == NULL if we can't find
+ * any reusable anon_vma.
* There's no absolute need to look only at touching neighbours:
* we could search further afield for "compatible" anon_vmas.
* But it would probably just be a waste of time searching,
@@ -1303,7 +1302,7 @@ struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
* We're trying to allow mprotect remerging later on,
* not trying to minimize memory used for anon_vmas.
*/
- return NULL;
+ return anon_vma;
}
/*
--
Thanks,
David / dhildenb
