[Xen-devel] [PATCH 23/24] [xen-unstable.hg] remove arbitrary limit in minios on number of grant refs it can accept

[Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>]

Changes the minios gntmap implementation to use a list instead of an array.
This allows it to grow as necessary to support any number of grants.

As an result of this change, setting a maximum number of grants doesn't make
much sense anymore, so it's now just a no-op.

Signed-off-by: Diego Ongaro <diego.ongaro@xxxxxxxxxx>
Signed-off-by: Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>
---

diff -r 7a579b4789b1 extras/mini-os/gntmap.c
--- a/extras/mini-os/gntmap.c   Wed Mar 18 16:34:53 2009 +0000
+++ b/extras/mini-os/gntmap.c   Wed Mar 18 17:17:11 2009 +0000
@@ -37,44 +37,20 @@
 #include <inttypes.h>
 #include "gntmap.h"
 
-#define DEFAULT_MAX_GRANTS 128
-
 struct gntmap_entry {
+    struct minios_list_head list;
     unsigned long host_addr;
     grant_handle_t handle;
 };
 
-static inline int
-gntmap_entry_used(struct gntmap_entry *entry)
-{
-    return entry->host_addr != 0;
-}
-
-static struct gntmap_entry*
-gntmap_find_free_entry(struct gntmap *map)
-{
-    int i;
-
-    for (i = 0; i < map->nentries; i++) {
-        if (!gntmap_entry_used(&map->entries[i]))
-            return &map->entries[i];
-    }
-
-#ifdef GNTMAP_DEBUG
-    printk("gntmap_find_free_entry(map=%p): all %d entries full\n",
-           map, map->nentries);
-#endif
-    return NULL;
-}
-
 static struct gntmap_entry*
 gntmap_find_entry(struct gntmap *map, unsigned long addr)
 {
-    int i;
+    struct gntmap_entry *i;
 
-    for (i = 0; i < map->nentries; i++) {
-        if (map->entries[i].host_addr == addr)
-            return &map->entries[i];
+    minios_list_for_each_entry(i, &map->entries, list) {
+        if (i->host_addr == addr)
+            return i;
     }
     return NULL;
 }
@@ -82,19 +58,6 @@
 int
 gntmap_set_max_grants(struct gntmap *map, int count)
 {
-#ifdef GNTMAP_DEBUG
-    printk("gntmap_set_max_grants(map=%p, count=%d)\n", map, count);
-#endif
-
-    if (map->nentries != 0)
-        return -EBUSY;
-
-    map->entries = xmalloc_array(struct gntmap_entry, count);
-    if (map->entries == NULL)
-        return -ENOMEM;
-
-    memset(map->entries, 0, sizeof(struct gntmap_entry) * count);
-    map->nentries = count;
     return 0;
 }
 
@@ -169,6 +132,8 @@
         }
 
         rc = _gntmap_unmap_grant_ref(ent);
+        minios_list_del(&ent->list);
+        xfree(ent);
         if (rc != 0)
             return rc;
     }
@@ -197,14 +162,12 @@
            refs, refs == NULL ? 0 : refs[0], writable);
 #endif
 
-    (void) gntmap_set_max_grants(map, DEFAULT_MAX_GRANTS);
-
     addr = allocate_ondemand((unsigned long) count, 1);
     if (addr == 0)
         return NULL;
 
     for (i = 0; i < count; i++) {
-        ent = gntmap_find_free_entry(map);
+        ent = xmalloc(struct gntmap_entry);
         if (ent == NULL ||
             _gntmap_map_grant_ref(ent,
                                   addr + PAGE_SIZE * i,
@@ -212,9 +175,11 @@
                                   refs[i],
                                   writable) != 0) {
 
+            xfree(ent);
             (void) gntmap_munmap(map, addr, i);
             return NULL;
         }
+        minios_list_add(&ent->list, &map->entries);
     }
 
     return (void*) addr;
@@ -226,27 +191,21 @@
 #ifdef GNTMAP_DEBUG
     printk("gntmap_init(map=%p)\n", map);
 #endif
-    map->nentries = 0;
-    map->entries = NULL;
+    MINIOS_INIT_LIST_HEAD(&map->entries);
 }
 
 void
 gntmap_fini(struct gntmap *map)
 {
-    struct gntmap_entry *ent;
-    int i;
+    struct gntmap_entry *ent, *tmp;
 
 #ifdef GNTMAP_DEBUG
     printk("gntmap_fini(map=%p)\n", map);
 #endif
 
-    for (i = 0; i < map->nentries; i++) {
-        ent = &map->entries[i];
-        if (gntmap_entry_used(ent))
-            (void) _gntmap_unmap_grant_ref(ent);
+    minios_list_for_each_entry_safe(ent, tmp, &map->entries, list) {
+        (void) _gntmap_unmap_grant_ref(ent);
+        minios_list_del(&ent->list);
+        xfree(ent);
     }
-
-    xfree(map->entries);
-    map->entries = NULL;
-    map->nentries = 0;
 }
diff -r 7a579b4789b1 extras/mini-os/include/gntmap.h
--- a/extras/mini-os/include/gntmap.h   Wed Mar 18 16:34:53 2009 +0000
+++ b/extras/mini-os/include/gntmap.h   Wed Mar 18 17:17:11 2009 +0000
@@ -2,14 +2,14 @@
 #define __GNTMAP_H__
 
 #include <os.h>
+#include "list.h"
 
 /*
  * Please consider struct gntmap opaque. If instead you choose to disregard
  * this message, I insist that you keep an eye out for raptors.
  */
 struct gntmap {
-    int nentries;
-    struct gntmap_entry *entries;
+    struct minios_list_head entries;
 };
 
 int


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