[Xen-changelog] [xen-unstable] libxc: Replace malloc with alloca in hot path

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Santosh Jodh <santosh.jodh@xxxxxxxxxx>
# Date 1328640410 0
# Node ID 8ba7ae0b070b4de93fc033067c61714c202d64c1
# Parent  0a28397a3ee5ce290a35c1b6e6c62466179c40eb
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@xxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---


diff -r 0a28397a3ee5 -r 8ba7ae0b070b tools/libxc/xc_linux_osdep.c
--- a/tools/libxc/xc_linux_osdep.c      Tue Feb 07 18:45:00 2012 +0000
+++ b/tools/libxc/xc_linux_osdep.c      Tue Feb 07 18:46:50 2012 +0000
@@ -243,7 +243,7 @@
          * 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 )
         {
@@ -289,8 +289,6 @@
                 break;
             }
 
-            free(pfn);
-
             if ( rc == -ENOENT && i == num )
                 rc = 0;
             else if ( rc )
@@ -525,7 +523,7 @@
     if (flags & XC_GRANT_MAP_SINGLE_DOMAIN)
         domids_stride = 0;
 
-    map = malloc(sizeof(*map) +
+    map = alloca(sizeof(*map) +
                  (count - 1) * sizeof(struct ioctl_gntdev_map_grant_ref));
     if ( map == NULL )
         return NULL;
@@ -599,7 +597,6 @@
     }
 
  out:
-    free(map);
 
     return addr;
 }

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