[PATCH 3/3] Xen/gntdev: don't needlessly use kvcalloc()

[Jan Beulich <jbeulich@xxxxxxxx>]

Requesting zeroed memory when all of it will be overwritten subsequently
by all ones is a waste of processing bandwidth. In fact, rather than
recording zeroed ->grants[], fill that array too with more appropriate
"invalid" indicators.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Use (now generalized) INVALID_GRANT_REF.

--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -133,9 +133,12 @@ struct gntdev_grant_map *gntdev_alloc_ma
        if (NULL == add)
                return NULL;
 
-       add->grants    = kvcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
-       add->map_ops   = kvcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
-       add->unmap_ops = kvcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
+       add->grants    = kvmalloc_array(count, sizeof(add->grants[0]),
+                                       GFP_KERNEL);
+       add->map_ops   = kvmalloc_array(count, sizeof(add->map_ops[0]),
+                                       GFP_KERNEL);
+       add->unmap_ops = kvmalloc_array(count, sizeof(add->unmap_ops[0]),
+                                       GFP_KERNEL);
        add->pages     = kvcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
        if (NULL == add->grants    ||
            NULL == add->map_ops   ||
@@ -143,10 +146,10 @@ struct gntdev_grant_map *gntdev_alloc_ma
            NULL == add->pages)
                goto err;
        if (use_ptemod) {
-               add->kmap_ops   = kvcalloc(count, sizeof(add->kmap_ops[0]),
-                                          GFP_KERNEL);
-               add->kunmap_ops = kvcalloc(count, sizeof(add->kunmap_ops[0]),
-                                          GFP_KERNEL);
+               add->kmap_ops   = kvmalloc_array(count, 
sizeof(add->kmap_ops[0]),
+                                                GFP_KERNEL);
+               add->kunmap_ops = kvmalloc_array(count, 
sizeof(add->kunmap_ops[0]),
+                                                GFP_KERNEL);
                if (NULL == add->kmap_ops || NULL == add->kunmap_ops)
                        goto err;
        }
@@ -186,6 +189,8 @@ struct gntdev_grant_map *gntdev_alloc_ma
                goto err;
 
        for (i = 0; i < count; i++) {
+               add->grants[i].domid = DOMID_INVALID;
+               add->grants[i].ref = INVALID_GRANT_REF;
                add->map_ops[i].handle = INVALID_GRANT_HANDLE;
                add->unmap_ops[i].handle = INVALID_GRANT_HANDLE;
                if (use_ptemod) {