[PATCH v9 06/11] xen: introduce rangeset_consume_ranges

[Roger Pau Monne <roger.pau@citrix.com>]

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@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
---
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Julien Grall <julien.grall@arm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Wei Liu <wei.liu2@citrix.com>
---
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 ade34f6a50..bb68ce62e4 100644
--- a/xen/common/rangeset.c
+++ b/xen/common/rangeset.c
@@ -350,6 +350,34 @@ int rangeset_claim_range(struct rangeset *r, unsigned long size,
     return 0;
 }
 
+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 1f83b1f44b..583b72bb0c 100644
--- a/xen/include/xen/rangeset.h
+++ b/xen/include/xen/rangeset.h
@@ -70,6 +70,16 @@ 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);
-- 
2.16.2


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