linux-kernel - [Patch v2 3/3] mm/mmap.c: extract __vma_unlink_list as counter part for __vma_link

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Date:   Sun,  6 Oct 2019 09:26:36 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     akpm@...ux-foundation.org, mgorman@...hsingularity.net,
        vbabka@...e.cz, osalvador@...e.de, hch@...radead.org,
        willy@...radead.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Wei Yang <richardw.yang@...ux.intel.com>
Subject: [Patch v2 3/3] mm/mmap.c: extract __vma_unlink_list as counter part for __vma_link_list

Just make the code a little easy to read.

Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>

---
Note: For nommu part, the code is not tested.

---
v2: rebase on top of 5.4-rc1
---
 mm/internal.h |  1 +
 mm/mmap.c     | 12 +-----------
 mm/nommu.c    |  8 +-------
 mm/util.c     | 14 ++++++++++++++
 4 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 8e596fa8a7de..f93fd474dac3 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -291,6 +291,7 @@ static inline bool is_data_mapping(vm_flags_t flags)
 /* mm/util.c */
 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
 		struct vm_area_struct *prev);
+void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma);
 
 #ifdef CONFIG_MMU
 extern long populate_vma_page_range(struct vm_area_struct *vma,
diff --git a/mm/mmap.c b/mm/mmap.c
index 2ca805209c47..3ab5d20289be 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -686,18 +686,8 @@ static __always_inline void __vma_unlink_common(struct mm_struct *mm,
 						struct vm_area_struct *vma,
 						struct vm_area_struct *ignore)
 {
-	struct vm_area_struct *prev, *next;
-
 	vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
-	next = vma->vm_next;
-	prev = vma->vm_prev;
-	if (prev)
-		prev->vm_next = next;
-	else
-		mm->mmap = next;
-	if (next)
-		next->vm_prev = prev;
-
+	__vma_unlink_list(mm, vma);
 	/* Kill the cache */
 	vmacache_invalidate(mm);
 }
diff --git a/mm/nommu.c b/mm/nommu.c
index 2bb923210128..21ddf689d4fa 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -673,13 +673,7 @@ static void delete_vma_from_mm(struct vm_area_struct *vma)
 	/* remove from the MM's tree and list */
 	rb_erase(&vma->vm_rb, &mm->mm_rb);
 
-	if (vma->vm_prev)
-		vma->vm_prev->vm_next = vma->vm_next;
-	else
-		mm->mmap = vma->vm_next;
-
-	if (vma->vm_next)
-		vma->vm_next->vm_prev = vma->vm_prev;
+	__vma_unlink_list(mm, vma);
 }
 
 /*
diff --git a/mm/util.c b/mm/util.c
index 023defd39a0d..988d11e6c17c 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -288,6 +288,20 @@ void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
 		next->vm_prev = vma;
 }
 
+void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+	struct vm_area_struct *prev, *next;
+
+	next = vma->vm_next;
+	prev = vma->vm_prev;
+	if (prev)
+		prev->vm_next = next;
+	else
+		mm->mmap = next;
+	if (next)
+		next->vm_prev = prev;
+}
+
 /* Check if the vma is being used as a stack by this task */
 int vma_is_stack_for_current(struct vm_area_struct *vma)
 {
-- 
2.17.1