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Subject[patch 1/3] smaps: extract pmd walker from smaps code
Extracts the pmd walker from smaps-specific code in fs/proc/task_mmu.c.

The new struct pmd_walker includes the struct vm_area_struct of the memory
to walk over. Iteration begins at the vma->vm_start and completes at
vma->vm_end. A pointer to another data structure may be stored in the
private field such as struct mem_size_stats, which acts as the smaps
accumulator. For each pmd in the VMA, the action function is called with
a pointer to its struct vm_area_struct, a pointer to the pmd_t, its
start and end addresses, and the private field.

The interface for walking pmd's in a VMA for fs/proc/task_mmu.c is now:

void for_each_pmd(struct vm_area_struct *vma,
void (*action)(struct vm_area_struct *vma,
pmd_t *pmd, unsigned long addr,
unsigned long end,
void *private),
void *private);

Since the pmd walker is now extracted from the smaps code, smaps_one_pmd()
is invoked for each pmd in the VMA. Its behavior and efficiency is
identical to the existing implementation.

Cc: Hugh Dickins <hugh@veritas.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
---
fs/proc/task_mmu.c | 69 +++++++++++++++++++++++++++++++--------------------
1 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -122,6 +122,13 @@ struct mem_size_stats
unsigned long private_dirty;
};

+struct pmd_walker {
+ struct vm_area_struct *vma;
+ void *private;
+ void (*action)(struct vm_area_struct *, pmd_t *, unsigned long,
+ unsigned long, void *);
+};
+
static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats *mss)
{
struct proc_maps_private *priv = m->private;
@@ -204,16 +211,17 @@ static int show_map(struct seq_file *m, void *v)
return show_map_internal(m, v, NULL);
}

-static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, unsigned long end,
- struct mem_size_stats *mss)
+static void smaps_one_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ void *private)
{
+ struct mem_size_stats *mss = private;
pte_t *pte, ptent;
spinlock_t *ptl;
struct page *page;

pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- do {
+ for (; addr != end; pte++, addr += PAGE_SIZE) {
ptent = *pte;
if (!pte_present(ptent))
continue;
@@ -235,57 +243,64 @@ static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
else
mss->private_clean += PAGE_SIZE;
}
- } while (pte++, addr += PAGE_SIZE, addr != end);
+ }
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
}

-static inline void smaps_pmd_range(struct vm_area_struct *vma, pud_t *pud,
- unsigned long addr, unsigned long end,
- struct mem_size_stats *mss)
+static inline void for_each_pmd_in_pud(struct pmd_walker *walker, pud_t *pud,
+ unsigned long addr, unsigned long end)
{
pmd_t *pmd;
unsigned long next;

- pmd = pmd_offset(pud, addr);
- do {
+ for (pmd = pmd_offset(pud, addr); addr != end;
+ pmd++, addr = next) {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
- smaps_pte_range(vma, pmd, addr, next, mss);
- } while (pmd++, addr = next, addr != end);
+ walker->action(walker->vma, pmd, addr, next, walker->private);
+ }
}

-static inline void smaps_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
- unsigned long addr, unsigned long end,
- struct mem_size_stats *mss)
+static inline void for_each_pud_in_pgd(struct pmd_walker *walker, pgd_t *pgd,
+ unsigned long addr, unsigned long end)
{
pud_t *pud;
unsigned long next;

- pud = pud_offset(pgd, addr);
- do {
+ for (pud = pud_offset(pgd, addr); addr != end;
+ pud++, addr = next) {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
- smaps_pmd_range(vma, pud, addr, next, mss);
- } while (pud++, addr = next, addr != end);
+ for_each_pmd_in_pud(walker, pud, addr, next);
+ }
}

-static inline void smaps_pgd_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
- struct mem_size_stats *mss)
+static inline void for_each_pmd(struct vm_area_struct *vma,
+ void (*action)(struct vm_area_struct *, pmd_t *,
+ unsigned long, unsigned long,
+ void *),
+ void *private)
{
+ unsigned long addr = vma->vm_start;
+ unsigned long end = vma->vm_end;
+ struct pmd_walker walker = {
+ .vma = vma,
+ .private = private,
+ .action = action,
+ };
pgd_t *pgd;
unsigned long next;

- pgd = pgd_offset(vma->vm_mm, addr);
- do {
+ for (pgd = pgd_offset(vma->vm_mm, addr); addr != end;
+ pgd++, addr = next) {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
- smaps_pud_range(vma, pgd, addr, next, mss);
- } while (pgd++, addr = next, addr != end);
+ for_each_pud_in_pgd(&walker, pgd, addr, next);
+ }
}

static int show_smap(struct seq_file *m, void *v)
@@ -295,7 +310,7 @@ static int show_smap(struct seq_file *m, void *v)

memset(&mss, 0, sizeof mss);
if (vma->vm_mm && !is_vm_hugetlb_page(vma))
- smaps_pgd_range(vma, vma->vm_start, vma->vm_end, &mss);
+ for_each_pmd(vma, smaps_one_pmd, &mss);
return show_map_internal(m, v, &mss);
}

-
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