[PATCH v2 1/4] virtio_balloon: separate vm events into a function

[zhenwei pi]

All the VM events related statistics have dependence on
'CONFIG_VM_EVENT_COUNTERS', once any stack variable is required by any
VM events in future, we would have codes like:
 #ifdef CONFIG_VM_EVENT_COUNTERS
      unsigned long foo;
 #endif
      ...
 #ifdef CONFIG_VM_EVENT_COUNTERS
      foo = events[XXX] + events[YYY];
      update_stat(vb, idx++, VIRTIO_BALLOON_S_XXX, foo);
 #endif

Separate vm events into a single function, also remove
'CONFIG_VM_EVENT_COUNTERS' from 'update_balloon_stats'.

Signed-off-by: zhenwei pi <pizhen...@bytedance.com>
---
 drivers/virtio/virtio_balloon.c | 44 ++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 1f5b3dd31fcf..59fe157e5722 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -316,34 +316,48 @@ static inline void update_stat(struct virtio_balloon *vb, 
int idx,
 
 #define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT)
 
-static unsigned int update_balloon_stats(struct virtio_balloon *vb)
+/* Return the number of entries filled by vm events */
+static inline unsigned int update_balloon_vm_stats(struct virtio_balloon *vb,
+                                                  unsigned int start)
 {
+#ifdef CONFIG_VM_EVENT_COUNTERS
        unsigned long events[NR_VM_EVENT_ITEMS];
-       struct sysinfo i;
-       unsigned int idx = 0;
-       long available;
-       unsigned long caches;
+       unsigned int idx = start;
 
        all_vm_events(events);
-       si_meminfo(&i);
-
-       available = si_mem_available();
-       caches = global_node_page_state(NR_FILE_PAGES);
-
-#ifdef CONFIG_VM_EVENT_COUNTERS
        update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
-                               pages_to_bytes(events[PSWPIN]));
+                   pages_to_bytes(events[PSWPIN]));
        update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
-                               pages_to_bytes(events[PSWPOUT]));
+                   pages_to_bytes(events[PSWPOUT]));
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
+
 #ifdef CONFIG_HUGETLB_PAGE
        update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC,
                    events[HTLB_BUDDY_PGALLOC]);
        update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL,
                    events[HTLB_BUDDY_PGALLOC_FAIL]);
-#endif
-#endif
+#endif /* CONFIG_HUGETLB_PAGE */
+
+       return idx - start;
+#else /* CONFIG_VM_EVENT_COUNTERS */
+
+       return 0;
+#endif /* CONFIG_VM_EVENT_COUNTERS */
+}
+
+static unsigned int update_balloon_stats(struct virtio_balloon *vb)
+{
+       struct sysinfo i;
+       unsigned int idx = 0;
+       long available;
+       unsigned long caches;
+
+       idx += update_balloon_vm_stats(vb, idx);
+
+       si_meminfo(&i);
+       available = si_mem_available();
+       caches = global_node_page_state(NR_FILE_PAGES);
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
                                pages_to_bytes(i.freeram));
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,
-- 
2.34.1