[RESEND RFC PATCH v2 1/1] mm/vmalloc.c: simplify /proc/vmallocinfo implementation

From: zijun_hu
Date: Wed Oct 12 2016 - 06:13:50 EST


From: zijun_hu <zijun_hu@xxxxxxx>

many seq_file helpers exist for simplifying implementation of virtual files
especially, for /proc nodes. however, the helpers for iteration over
list_head are available but aren't adopted to implement /proc/vmallocinfo
currently.

simplify /proc/vmallocinfo implementation by existing seq_file helpers

Signed-off-by: zijun_hu <zijun_hu@xxxxxxx>
---
Changes in v2:
- the redundant type cast is removed as advised by rientjes@xxxxxxxxxx
- commit messages are updated

mm/vmalloc.c | 27 +++++----------------------
1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f2481cb4e6b2..e73948afac70 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2574,32 +2574,13 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
static void *s_start(struct seq_file *m, loff_t *pos)
__acquires(&vmap_area_lock)
{
- loff_t n = *pos;
- struct vmap_area *va;
-
spin_lock(&vmap_area_lock);
- va = list_first_entry(&vmap_area_list, typeof(*va), list);
- while (n > 0 && &va->list != &vmap_area_list) {
- n--;
- va = list_next_entry(va, list);
- }
- if (!n && &va->list != &vmap_area_list)
- return va;
-
- return NULL;
-
+ return seq_list_start(&vmap_area_list, *pos);
}

static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
- struct vmap_area *va = p, *next;
-
- ++*pos;
- next = list_next_entry(va, list);
- if (&next->list != &vmap_area_list)
- return next;
-
- return NULL;
+ return seq_list_next(p, &vmap_area_list, pos);
}

static void s_stop(struct seq_file *m, void *p)
@@ -2634,9 +2615,11 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)

static int s_show(struct seq_file *m, void *p)
{
- struct vmap_area *va = p;
+ struct vmap_area *va;
struct vm_struct *v;

+ va = list_entry(p, struct vmap_area, list);
+
/*
* s_show can encounter race with remove_vm_area, !VM_VM_AREA on
* behalf of vmap area is being tear down or vm_map_ram allocation.
--
1.9.1