[PATCH 1/2] xen/mm: Alter get_outstanding_claims() to return information by value

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

A void function with two output parameters is a weird choice.  Instead, return
a two-element structure.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Roger Pau Monné <roger@xxxxxxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Bernhard Kaindl <bernhard.kaindl@xxxxxxxxxx>

Slightly RFC.  claim_info_t name subject to improvement, but see next patch.

This is to help unwedge the XenServer patchqueue following commit
44adbac3c7a6 ("xen/mm: Introduce per-node free page counter").
---
 xen/common/page_alloc.c | 10 +++++++---
 xen/common/sysctl.c     |  8 ++++++--
 xen/include/xen/mm.h    |  6 +++++-
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 598222e2c2e1..900fcf5755c1 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -582,12 +582,16 @@ int domain_set_outstanding_pages(struct domain *d, 
unsigned long pages)
 }
 
 #ifdef CONFIG_SYSCTL
-void get_outstanding_claims(uint64_t *free_pages, uint64_t *outstanding_pages)
+claim_info_t get_outstanding_claims(void)
 {
+    claim_info_t info;
+
     spin_lock(&heap_lock);
-    *outstanding_pages = outstanding_claims;
-    *free_pages = avail_heap_pages(MEMZONE_XEN + 1, NR_ZONES - 1, -1);
+    info.avail   = avail_heap_pages(MEMZONE_XEN + 1, NR_ZONES - 1, -1);
+    info.claimed = outstanding_claims;
     spin_unlock(&heap_lock);
+
+    return info;
 }
 #endif /* CONFIG_SYSCTL */
 
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index 8fb5ff0af317..35c132564ef1 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -248,6 +248,7 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) 
u_sysctl)
     case XEN_SYSCTL_physinfo:
     {
         struct xen_sysctl_physinfo *pi = &op->u.physinfo;
+        claim_info_t claim_info;
 
         memset(pi, 0, sizeof(*pi));
         pi->threads_per_core =
@@ -259,8 +260,11 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) 
u_sysctl)
         pi->max_node_id = MAX_NUMNODES-1;
         pi->max_cpu_id = nr_cpu_ids - 1;
         pi->total_pages = total_pages;
-        /* Protected by lock */
-        get_outstanding_claims(&pi->free_pages, &pi->outstanding_pages);
+
+        claim_info = get_outstanding_claims();
+        pi->free_pages = claim_info.avail;
+        pi->outstanding_pages = claim_info.claimed;
+
         pi->scrub_pages = 0;
         pi->cpu_khz = cpu_khz;
         pi->max_mfn = get_upper_mfn_bound();
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index b80bec00c124..74d28d2a1b7a 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -132,7 +132,11 @@ int populate_pt_range(unsigned long virt, unsigned long 
nr_mfns);
 unsigned long __must_check domain_adjust_tot_pages(struct domain *d,
     long pages);
 int domain_set_outstanding_pages(struct domain *d, unsigned long pages);
-void get_outstanding_claims(uint64_t *free_pages, uint64_t *outstanding_pages);
+
+typedef struct {
+    unsigned long avail, claimed;
+} claim_info_t;
+claim_info_t get_outstanding_claims(void);
 
 /* Domain suballocator. These functions are *not* interrupt-safe.*/
 void init_domheap_pages(paddr_t ps, paddr_t pe);
-- 
2.39.5