File 23128-xentrace_correct_formula_to_calculate_t_i... of Package xen

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File 23128-xentrace_correct_formula_to_calculate_t_info_pages.patch of Package xen (Revision 43b25d1f7f5589dd235134f645453186)

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changeset:   23128:4a335f1000ea
user:        Olaf Hering <olaf@aepfle.de>
date:        Sat Apr 02 15:50:19 2011 +0100
files:       xen/common/trace.c
description:
xentrace: correct formula to calculate t_info_pages

The current formula to calculate t_info_pages, based on the initial
code, is slightly incorrect. It may allocate more than needed.
Each cpu has some pages/mfns stored as uint32_t.
That list is stored with an offset at tinfo.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>

---
 xen/common/trace.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: xen-4.1.2-testing/xen/common/trace.c
===================================================================
--- xen-4.1.2-testing.orig/xen/common/trace.c
+++ xen-4.1.2-testing/xen/common/trace.c
@@ -110,7 +110,7 @@ static int calculate_tbuf_size(unsigned
 {
     struct t_buf dummy;
     typeof(dummy.prod) size;
-    unsigned int t_info_words, t_info_bytes;
+    unsigned int t_info_words;
 
     /* force maximum value for an unsigned type */
     size = -1;
@@ -125,9 +125,8 @@ static int calculate_tbuf_size(unsigned
         pages = size;
     }
 
-    t_info_words = num_online_cpus() * pages + t_info_first_offset;
-    t_info_bytes = t_info_words * sizeof(uint32_t);
-    t_info_pages = PFN_UP(t_info_bytes);
+    t_info_words = num_online_cpus() * pages * sizeof(uint32_t);
+    t_info_pages = PFN_UP(t_info_first_offset + t_info_words);
     printk(XENLOG_INFO "xentrace: requesting %u t_info pages "
            "for %u trace pages on %u cpus\n",
            t_info_pages, pages, num_online_cpus());

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File 23128-xentrace_correct_formula_to_calculate_t_info_pages.patch of Package xen (Revision 43b25d1f7f5589dd235134f645453186)

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