[Xen-devel] [PATCH] xen: centralize accounting for domain tot_pages

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

xen: centralize accounting for domain tot_pages

Provide and use a common function for all adjustments to a
domain's tot_pages counter in anticipation of future and/or
out-of-tree patches that must adjust related counters
atomically.

Signed-off-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>

 arch/x86/mm.c             |    4 ++--
 arch/x86/mm/mem_sharing.c |    4 ++--
 common/grant_table.c      |    2 +-
 common/memory.c           |    2 +-
 common/page_alloc.c       |   10 ++++++++--
 include/xen/mm.h          |    2 ++
 6 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index ab94b02..3887ca6 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3842,7 +3842,7 @@ int donate_page(
     {
         if ( d->tot_pages >= d->max_pages )
             goto fail;
-        d->tot_pages++;
+        domain_adjust_tot_pages(d, 1);
     }
 
     page->count_info = PGC_allocated | 1;
@@ -3892,7 +3892,7 @@ int steal_page(
     } while ( (y = cmpxchg(&page->count_info, x, x | 1)) != x );
 
     /* Unlink from original owner. */
-    if ( !(memflags & MEMF_no_refcount) && !--d->tot_pages )
+    if ( !(memflags & MEMF_no_refcount) && !domain_adjust_tot_pages(d, -1) )
         drop_dom_ref = 1;
     page_list_del(page, &d->page_list);
 
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 5103285..e91aac5 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -639,7 +639,7 @@ static int page_make_sharable(struct domain *d,
     }
 
     page_set_owner(page, dom_cow);
-    d->tot_pages--;
+    domain_adjust_tot_pages(d, -1);
     drop_dom_ref = (d->tot_pages == 0);
     page_list_del(page, &d->page_list);
     spin_unlock(&d->page_alloc_lock);
@@ -680,7 +680,7 @@ static int page_make_private(struct domain *d, struct 
page_info *page)
     ASSERT(page_get_owner(page) == dom_cow);
     page_set_owner(page, d);
 
-    if ( d->tot_pages++ == 0 )
+    if ( domain_adjust_tot_pages(d, 1) == 1 )
         get_domain(d);
     page_list_add_tail(page, &d->page_list);
     spin_unlock(&d->page_alloc_lock);
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 7912769..ca8d861 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -1656,7 +1656,7 @@ gnttab_transfer(
         }
 
         /* Okay, add the page to 'e'. */
-        if ( unlikely(e->tot_pages++ == 0) )
+        if ( unlikely(domain_adjust_tot_pages(e, 1) == 1) )
             get_knownalive_domain(e);
         page_list_add_tail(page, &e->page_list);
         page_set_owner(page, e);
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 83e2666..9842ea9 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -454,7 +454,7 @@ static long 
memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
                              (j * (1UL << exch.out.extent_order)));
 
                 spin_lock(&d->page_alloc_lock);
-                d->tot_pages -= dec_count;
+                domain_adjust_tot_pages(d, -dec_count);
                 drop_dom_ref = (dec_count && !d->tot_pages);
                 spin_unlock(&d->page_alloc_lock);
 
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 15ebc66..e273bb7 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -239,6 +239,12 @@ static long midsize_alloc_zone_pages;
 
 static DEFINE_SPINLOCK(heap_lock);
 
+unsigned long domain_adjust_tot_pages(struct domain *d, long pages)
+{
+    ASSERT(spin_is_locked(&d->page_alloc_lock));
+    return d->tot_pages += pages;
+}
+
 static unsigned long init_node_heap(int node, unsigned long mfn,
                                     unsigned long nr, bool_t *use_tail)
 {
@@ -1291,7 +1297,7 @@ int assign_pages(
         if ( unlikely(d->tot_pages == 0) )
             get_knownalive_domain(d);
 
-        d->tot_pages += 1 << order;
+        domain_adjust_tot_pages(d, 1 << order);
     }
 
     for ( i = 0; i < (1 << order); i++ )
@@ -1375,7 +1381,7 @@ void free_domheap_pages(struct page_info *pg, unsigned 
int order)
             page_list_del2(&pg[i], &d->page_list, &d->arch.relmem_list);
         }
 
-        d->tot_pages -= 1 << order;
+        domain_adjust_tot_pages(d, -(1 << order));
         drop_dom_ref = (d->tot_pages == 0);
 
         spin_unlock_recursive(&d->page_alloc_lock);
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 64a0cc1..00b1915 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -48,6 +48,8 @@ void free_xenheap_pages(void *v, unsigned int order);
 #define alloc_xenheap_page() (alloc_xenheap_pages(0,0))
 #define free_xenheap_page(v) (free_xenheap_pages(v,0))
 
+unsigned long domain_adjust_tot_pages(struct domain *d, long pages);
+
 /* Domain suballocator. These functions are *not* interrupt-safe.*/
 void init_domheap_pages(paddr_t ps, paddr_t pe);
 struct page_info *alloc_domheap_pages(

Attachment: adjusttot-121128.patch
Description: Binary data

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