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mm/mmap: add inline vma_next() for readability of mmap code 

There are three places that the next vma is required which uses the same
block of code.  Replace the block with a function and add comments on what
happens in the case where NULL is encountered.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200818154707.2515169-1-Liam.Howlett@Oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2020-10-17 16:14:06 -07:00 committed by Linus Torvalds
parent 4dc200cee1
commit 3903b55a61
1 changed files with 20 additions and 6 deletions
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26
mm/mmap.c
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@ -558,6 +558,23 @@ static int find_vma_links(struct mm_struct *mm, unsigned long addr,
return 0; return 0;
} }
/*
* vma_next() - Get the next VMA.
* @mm: The mm_struct.
* @vma: The current vma.
*
* If @vma is NULL, return the first vma in the mm.
*
* Returns: The next VMA after @vma.
*/
static inline struct vm_area_struct *vma_next(struct mm_struct *mm,
struct vm_area_struct *vma)
{
if (!vma)
return mm->mmap;
return vma->vm_next;
}
static unsigned long count_vma_pages_range(struct mm_struct *mm, static unsigned long count_vma_pages_range(struct mm_struct *mm,
unsigned long addr, unsigned long end) unsigned long addr, unsigned long end)
{ {
@ -1128,10 +1145,7 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
if (vm_flags & VM_SPECIAL) if (vm_flags & VM_SPECIAL)
return NULL; return NULL;
if (prev) next = vma_next(mm, prev);
next = prev->vm_next;
else
next = mm->mmap;
area = next; area = next;
if (area && area->vm_end == end) /* cases 6, 7, 8 */ if (area && area->vm_end == end) /* cases 6, 7, 8 */
next = next->vm_next; next = next->vm_next;
@ -2632,7 +2646,7 @@ static void unmap_region(struct mm_struct *mm,
struct vm_area_struct *vma, struct vm_area_struct *prev, struct vm_area_struct *vma, struct vm_area_struct *prev,
unsigned long start, unsigned long end) unsigned long start, unsigned long end)
{ {
struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap; struct vm_area_struct *next = vma_next(mm, prev);
struct mmu_gather tlb; struct mmu_gather tlb;
lru_add_drain(); lru_add_drain();
@ -2831,7 +2845,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
if (error) if (error)
return error; return error;
} }
vma = prev ? prev->vm_next : mm->mmap; vma = vma_next(mm, prev);
if (unlikely(uf)) { if (unlikely(uf)) {
/* /*