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[libvirt] [PATCH 6/7] Introduce virNetDevBandwidthUpdateFilter



This is practically a wrapper over
virNetDevBandwidthManipulateFilter() that will update the desired
filter on an interface (usually a network bridge) with a new MAC
address. Although, the MAC address in question usually refers to
some other interface - the one that the filter is constructed
for. Yeah, hard to parse. Thing is, our NATed network has a
bridge where some part of QoS takes place. And vNICs from guests
are plugged into the bridge. However, if a guest decides to
change the MAC of its vNIC, corresponding qemu process emits an
event to which we respond somehow. However, our QoS hierarchy is
currently not notified, therefore it falls apart. This function
(when called from the correct place) will update our QoS
hierarchy and duck tape it together again.

Signed-off-by: Michal Privoznik <mprivozn redhat com>
---
 src/libvirt_private.syms      |  1 +
 src/util/virnetdevbandwidth.c | 38 ++++++++++++++++++++++++++++++++++++++
 src/util/virnetdevbandwidth.h |  6 ++++++
 3 files changed, 45 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 7166283..547a919 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1753,6 +1753,7 @@ virNetDevBandwidthFree;
 virNetDevBandwidthPlug;
 virNetDevBandwidthSet;
 virNetDevBandwidthUnplug;
+virNetDevBandwidthUpdateFilter;
 virNetDevBandwidthUpdateRate;
 
 
diff --git a/src/util/virnetdevbandwidth.c b/src/util/virnetdevbandwidth.c
index c57c8c0..0c49b41 100644
--- a/src/util/virnetdevbandwidth.c
+++ b/src/util/virnetdevbandwidth.c
@@ -680,3 +680,41 @@ virNetDevBandwidthUpdateRate(const char *ifname,
     VIR_FREE(ceil);
     return ret;
 }
+
+/**
+ * virNetDevBandwidthUpdateFilter:
+ * @ifname: interface to operate on
+ * @ifmac_ptr: new MAC to update the filter with
+ * @id: filter ID
+ *
+ * Sometimes the host environment is so dynamic, that even
+ * guest's MAC addresses change on the fly. That's when we must
+ * update our QoS hierarchy so that guest's traffic is placed
+ * into correct QDiscs. This function does exactly that. On the
+ * interface @ifname (usually a bridge) updates filter with
+ * unique identifier @id so that it reflects fact, that new
+ * address corresponding to the filter has changed to @ifmac_ptr.
+ *
+ * Returns: 0 on success,
+ *         -1 on failure (with error reported).
+ */
+int
+virNetDevBandwidthUpdateFilter(const char *ifname,
+                               const virMacAddr *ifmac_ptr,
+                               unsigned int id)
+{
+    int ret = -1;
+    char *class_id = NULL;
+
+    if (virAsprintf(&class_id, "1:%x", id) < 0)
+        goto cleanup;
+
+    if (virNetDevBandwidthManipulateFilter(ifname, ifmac_ptr, id,
+                                           class_id, true, true) < 0)
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    VIR_FREE(class_id);
+    return ret;
+}
diff --git a/src/util/virnetdevbandwidth.h b/src/util/virnetdevbandwidth.h
index efcf95a..9b1d2a6 100644
--- a/src/util/virnetdevbandwidth.h
+++ b/src/util/virnetdevbandwidth.h
@@ -73,4 +73,10 @@ int virNetDevBandwidthUpdateRate(const char *ifname,
                                  unsigned long long new_rate)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
     ATTRIBUTE_RETURN_CHECK;
+
+int virNetDevBandwidthUpdateFilter(const char *ifname,
+                                   const virMacAddr *ifmac_ptr,
+                                   unsigned int id)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
+    ATTRIBUTE_RETURN_CHECK;
 #endif /* __VIR_NETDEV_BANDWIDTH_H__ */
-- 
2.0.5


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