[Xen-devel] [PATCH v7 for-next 08/12] xen: introduce rangeset_consume_ranges

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

This function allows to iterate over a rangeset while removing the
processed regions.

This will be used in order to split processing of large memory areas
when mapping them into the guest p2m.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Changes since v6:
 - Expand commit message.
 - Add a comment to describe the expected function behavior.
 - Fix indentation.

Changes since v5:
 - New in this version.
---
 xen/common/rangeset.c      | 28 ++++++++++++++++++++++++++++
 xen/include/xen/rangeset.h | 10 ++++++++++
 2 files changed, 38 insertions(+)

diff --git a/xen/common/rangeset.c b/xen/common/rangeset.c
index 6c6293c15c..fd4a6b3384 100644
--- a/xen/common/rangeset.c
+++ b/xen/common/rangeset.c
@@ -298,6 +298,34 @@ int rangeset_report_ranges(
     return rc;
 }
 
+int rangeset_consume_ranges(
+    struct rangeset *r,
+    int (*cb)(unsigned long s, unsigned long e, void *, unsigned long *c),
+    void *ctxt)
+{
+    int rc = 0;
+
+    write_lock(&r->lock);
+    while ( !rangeset_is_empty(r) )
+    {
+        unsigned long consumed = 0;
+        struct range *x = first_range(r);
+
+        rc = cb(x->s, x->e, ctxt, &consumed);
+
+        ASSERT(consumed <= x->e - x->s + 1);
+        x->s += consumed;
+        if ( x->s > x->e )
+            destroy_range(r, x);
+
+        if ( rc )
+            break;
+    }
+    write_unlock(&r->lock);
+
+    return rc;
+}
+
 int rangeset_add_singleton(
     struct rangeset *r, unsigned long s)
 {
diff --git a/xen/include/xen/rangeset.h b/xen/include/xen/rangeset.h
index aa6408248b..0c648d9621 100644
--- a/xen/include/xen/rangeset.h
+++ b/xen/include/xen/rangeset.h
@@ -68,6 +68,16 @@ int rangeset_report_ranges(
     struct rangeset *r, unsigned long s, unsigned long e,
     int (*cb)(unsigned long s, unsigned long e, void *), void *ctxt);
 
+/*
+ * Note that the consume function can return an error value apart from
+ * -ERESTART, and that no cleanup is performed (ie: the user should call
+ * rangeset_destroy if needed).
+ */
+int rangeset_consume_ranges(struct rangeset *r,
+                            int (*cb)(unsigned long s, unsigned long e,
+                                      void *, unsigned long *c),
+                            void *ctxt);
+
 /* Add/remove/query a single number. */
 int __must_check rangeset_add_singleton(
     struct rangeset *r, unsigned long s);
-- 
2.13.5 (Apple Git-94)


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