[Xen-devel] [PATCH 01 of 10] Simplify include/xen/grant_table.h a bit:

[<steven.smith@xxxxxxxxxx>]

# HG changeset patch
# User Steven Smith <steven.smith@xxxxxxxxxxxxx>
# Date 1222082607 -3600
# Node ID 5f2f5565914573282437bb31f790ffac1169755c
# Parent  6f63970032a3fe5fda585beba929d2d7a5e14861
Simplify include/xen/grant_table.h a bit:

-- INITIAL_GRANT_ENTRIES is never used, so can be removed.
-- Simplify num_act_frames_from_sha_frames a little.

Signed-off-by: Steven Smith <steven.smith@xxxxxxxxxx>

diff -r 6f63970032a3 -r 5f2f55659145 xen/include/xen/grant_table.h
--- a/xen/include/xen/grant_table.h     Fri Oct 02 09:10:27 2009 +0100
+++ b/xen/include/xen/grant_table.h     Mon Sep 22 12:23:27 2008 +0100
@@ -52,10 +52,6 @@
 #define GNTPIN_devr_shift    (24)
 #define GNTPIN_devr_inc      (1 << GNTPIN_devr_shift)
 #define GNTPIN_devr_mask     (0xFFU << GNTPIN_devr_shift)
-
-/* Initial size of a grant table. */
-#define INITIAL_NR_GRANT_ENTRIES ((INITIAL_NR_GRANT_FRAMES << PAGE_SHIFT) / \
-                                     sizeof(grant_entry_t))
 
 #ifndef DEFAULT_MAX_NR_GRANT_FRAMES /* to allow arch to override */
 /* Default maximum size of a grant table. [POLICY] */
@@ -128,16 +124,13 @@
 num_act_frames_from_sha_frames(const unsigned int num)
 {
     /* How many frames are needed for the active grant table,
-     * given the size of the shared grant table?
-     *
-     * act_per_page = PAGE_SIZE / sizeof(active_grant_entry_t);
-     * sha_per_page = PAGE_SIZE / sizeof(grant_entry_t);
-     * num_sha_entries = num * sha_per_page;
-     * num_act_frames = (num_sha_entries + (act_per_page-1)) / act_per_page;
-     */
-    return ((num * (PAGE_SIZE / sizeof(grant_entry_t))) +
-            ((PAGE_SIZE / sizeof(struct active_grant_entry))-1))
-           / (PAGE_SIZE / sizeof(struct active_grant_entry));
+     * given the size of the shared grant table? */
+    unsigned act_per_page = PAGE_SIZE / sizeof(struct active_grant_entry);
+    unsigned sha_per_page = PAGE_SIZE / sizeof(grant_entry_t);
+    unsigned num_sha_entries = num * sha_per_page;
+    unsigned num_act_frames =
+        (num_sha_entries + (act_per_page-1)) / act_per_page;
+    return num_act_frames;
 }
 
 static inline unsigned int

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