libxc: Replace malloc with alloca in hot path

Replace malloc with alloc in hot paths for improved performance.

Signed-off-by: Santosh Jodh <santosh.jodh@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
xen-unstable changeset:   24709:8ba7ae0b070b
xen-unstable date:        Tue Feb 07 18:46:50 2012 +0000

1 files changed, 2 insertions, 5 deletions

diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
index 377c93867a..5ef5cd63f5 100644
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -218,7 +218,7 @@ static void *linux_privcmd_map_foreign_bulk(xc_interface *xch, xc_osdep_handle h
          * IOCTL_PRIVCMD_MMAPBATCH_V2 is not supported - fall back to
          * IOCTL_PRIVCMD_MMAPBATCH.
          */
-        xen_pfn_t *pfn = malloc(num * sizeof(*pfn));
+        xen_pfn_t *pfn = alloca(num * sizeof(*pfn));
 
         if ( pfn )
         {
@@ -264,8 +264,6 @@ static void *linux_privcmd_map_foreign_bulk(xc_interface *xch, xc_osdep_handle h
                 break;
             }
 
-            free(pfn);
-
             if ( rc == -ENOENT && i == num )
                 rc = 0;
             else if ( rc )
@@ -532,7 +530,7 @@ static void *do_gnttab_map_grant_refs(xc_gnttab *xch, xc_osdep_handle h,
     void *addr = NULL;
     int i;
 
-    map = malloc(sizeof(*map) +
+    map = alloca(sizeof(*map) +
                  (count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
     if ( map == NULL )
         return NULL;
@@ -567,7 +565,6 @@ static void *do_gnttab_map_grant_refs(xc_gnttab *xch, xc_osdep_handle h,
     }
 
  out:
-    free(map);
 
     return addr;
 }