mm/vmalloc.c: simplify /proc/vmallocinfo implementation

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 using existing seq_file
helpers.

Link: http://lkml.kernel.org/r/57FDF2E5.1000201@zoho.com
Signed-off-by: zijun_hu <zijun_hu@htc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f2481cb4e6b216e40252b0000b5fcea0d3cb9d30..e73948afac70ed2c52ca19006e9e9520f497b55b 100644 (file)
--- 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.