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mm/mmap: add inline munmap_vma_range() for code readability 

There are two locations that have a block of code for munmapping a vma
range.  Change those two locations to use a function and add meaningful
comments about what happens to the arguments, which was unclear in the
previous code.

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/20200818154707.2515169-2-Liam.Howlett@Oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Liam R. Howlett 2020-10-17 16:14:09 -07:00 committed by Linus Torvalds
parent 3903b55a61
commit fb8090b699
1 changed files with 33 additions and 15 deletions
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48
mm/mmap.c
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@ -575,6 +575,33 @@ static inline struct vm_area_struct *vma_next(struct mm_struct *mm,
return vma->vm_next;
}
/*
* munmap_vma_range() - munmap VMAs that overlap a range.
* @mm: The mm struct
* @start: The start of the range.
* @len: The length of the range.
* @pprev: pointer to the pointer that will be set to previous vm_area_struct
* @rb_link: the rb_node
* @rb_parent: the parent rb_node
*
* Find all the vm_area_struct that overlap from @start to
* @end and munmap them. Set @pprev to the previous vm_area_struct.
*
* Returns: -ENOMEM on munmap failure or 0 on success.
*/
static inline int
munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len,
struct vm_area_struct **pprev, struct rb_node ***link,
struct rb_node **parent, struct list_head *uf)
{
while (find_vma_links(mm, start, start + len, pprev, link, parent))
if (do_munmap(mm, start, len, uf))
return -ENOMEM;
return 0;
}
static unsigned long count_vma_pages_range(struct mm_struct *mm,
unsigned long addr, unsigned long end)
{
@ -1721,13 +1748,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
return -ENOMEM;
}
/* Clear old maps */
while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
&rb_parent)) {
if (do_munmap(mm, addr, len, uf))
return -ENOMEM;
}
/* Clear old maps, set up prev, rb_link, rb_parent, and uf */
if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
return -ENOMEM;
/*
* Private writable mapping: check memory availability
*/
@ -3063,14 +3086,9 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
if (error)
return error;
/*
* Clear old maps. this also does some error checking for us
*/
while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
&rb_parent)) {
if (do_munmap(mm, addr, len, uf))
return -ENOMEM;
}
/* Clear old maps, set up prev, rb_link, rb_parent, and uf */
if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
return -ENOMEM;
/* Check against address space limits *after* clearing old maps... */
if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))