[PATCH 1/5] netdev: Introduce several helper functions for generating unique netdev name
Shi Lei
shi_lei at massclouds.com
Fri Dec 4 07:01:31 UTC 2020
Extract ReserveName/GenerateName from netdevtap and netdevmacvlan as
common helper functions. Along with them, export Lock/Unlock functions
to protect these processes.
Signed-off-by: Shi Lei <shi_lei at massclouds.com>
---
src/libvirt_private.syms | 4 ++
src/util/virnetdev.c | 140 +++++++++++++++++++++++++++++++++++++++
src/util/virnetdev.h | 33 +++++++++
3 files changed, 177 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 2f640ef1..be3148c9 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2551,6 +2551,7 @@ virNetDevDelMulti;
virNetDevExists;
virNetDevFeatureTypeFromString;
virNetDevFeatureTypeToString;
+virNetDevGenerateName;
virNetDevGetFeatures;
virNetDevGetIndex;
virNetDevGetLinkInfo;
@@ -2572,8 +2573,10 @@ virNetDevGetVLanID;
virNetDevIfStateTypeFromString;
virNetDevIfStateTypeToString;
virNetDevIsVirtualFunction;
+virNetDevLockGenName;
virNetDevPFGetVF;
virNetDevReadNetConfig;
+virNetDevReserveName;
virNetDevRunEthernetScript;
virNetDevRxFilterFree;
virNetDevRxFilterModeTypeFromString;
@@ -2594,6 +2597,7 @@ virNetDevSetRcvMulti;
virNetDevSetRootQDisc;
virNetDevSetupControl;
virNetDevSysfsFile;
+virNetDevUnlockGenName;
virNetDevValidateConfig;
virNetDevVFInterfaceStats;
diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index 5104bbe7..5ff8e35f 100644
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -17,6 +17,7 @@
*/
#include <config.h>
+#include <math.h>
#include "virnetdev.h"
#include "viralloc.h"
@@ -95,6 +96,22 @@ VIR_LOG_INIT("util.netdev");
(FEATURE_WORD(blocks, index, field) & FEATURE_FIELD_FLAG(index))
#endif
+VIR_ENUM_IMPL(virNetDevGenNameType,
+ VIR_NET_DEV_GEN_NAME_LAST,
+ "none",
+ "tap",
+ "macvtap",
+ "macvlan",
+);
+
+static virNetDevGenName
+virNetDevGenNames[VIR_NET_DEV_GEN_NAME_LAST] = {
+ {0, NULL, VIR_MUTEX_INITIALIZER},
+ {-1, VIR_NET_GENERATED_TAP_PREFIX, VIR_MUTEX_INITIALIZER},
+ {-1, VIR_NET_GENERATED_MACVTAP_PREFIX, VIR_MUTEX_INITIALIZER},
+ {-1, VIR_NET_GENERATED_MACVLAN_PREFIX, VIR_MUTEX_INITIALIZER},
+};
+
typedef enum {
VIR_MCAST_TYPE_INDEX_TOKEN,
VIR_MCAST_TYPE_NAME_TOKEN,
@@ -3516,3 +3533,126 @@ virNetDevSetRootQDisc(const char *ifname,
return 0;
}
+
+
+/**
+ * virNetDevReserveName:
+ * @name: name of an existing network device
+ * @type: type of the network device
+ * @locked: whether this process is locked by the internal mutex
+ *
+ * Reserve a network device name, so that any new network device
+ * created with an autogenerated name will use a number higher
+ * than the number in the given device name.
+ *
+ * Returns nothing.
+ */
+void
+virNetDevReserveName(const char *name,
+ virNetDevGenNameType type,
+ bool locked)
+{
+ unsigned int id;
+ const char *idstr = NULL;
+
+ if (type && STRPREFIX(name, virNetDevGenNames[type].prefix)) {
+
+ VIR_INFO("marking device in use: '%s'", name);
+
+ idstr = name + strlen(virNetDevGenNames[type].prefix);
+
+ if (virStrToLong_ui(idstr, NULL, 10, &id) >= 0) {
+ if (locked)
+ virMutexLock(&virNetDevGenNames[type].mutex);
+
+ if (virNetDevGenNames[type].lastID < (int)id)
+ virNetDevGenNames[type].lastID = id;
+
+ if (locked)
+ virMutexUnlock(&virNetDevGenNames[type].mutex);
+ }
+ }
+}
+
+
+/**
+ * virNetDevGenerateName:
+ * @ifname: pointer to pointer to string containing template
+ *
+ * generate a new (currently unused) name for a new network device based
+ * on the templace string in @ifname - replace %d with the reserved id,
+ * and keep trying new values until one is found
+ * that doesn't already exist, or we've tried 10000 different
+ * names. Once a usable name is found, replace the template with the
+ * actual name.
+ *
+ * Returns 0 on success, -1 on failure.
+ */
+int
+virNetDevGenerateName(char **ifname, virNetDevGenNameType type)
+{
+ int id;
+ const char *prefix = virNetDevGenNames[type].prefix;
+ double maxIDd = pow(10, IFNAMSIZ - 1 - strlen(prefix));
+ int maxID = INT_MAX;
+ int attempts = 0;
+
+ if (maxIDd <= (double)INT_MAX)
+ maxID = (int)maxIDd;
+
+ do {
+ g_autofree char *try = NULL;
+
+ id = ++virNetDevGenNames[type].lastID;
+
+ /* reset before overflow */
+ if (virNetDevGenNames[type].lastID >= maxID)
+ virNetDevGenNames[type].lastID = -1;
+
+ if (*ifname)
+ try = g_strdup_printf(*ifname, id);
+ else
+ try = g_strdup_printf("%s%d", prefix, id);
+
+ if (!virNetDevExists(try)) {
+ g_free(*ifname);
+ *ifname = g_steal_pointer(&try);
+ return 0;
+ }
+ } while (++attempts < 10000);
+
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("no unused %s names available"),
+ prefix);
+ return -1;
+}
+
+
+/**
+ * virNetDevLockGenName:
+ * @type: type of the network device
+ *
+ * Lock the internal mutex for creation for this network device type.
+ *
+ * Returns nothing.
+ */
+void
+virNetDevLockGenName(virNetDevGenNameType type)
+{
+ virMutexLock(&virNetDevGenNames[type].mutex);
+}
+
+
+/**
+ * virNetDevUnlockGenName:
+ * @type: type of the network device
+ *
+ * Unlock the internal mutex for creation for this network device type.
+ *
+ * Returns nothing.
+ */
+void
+virNetDevUnlockGenName(virNetDevGenNameType type)
+{
+ virMutexUnlock(&virNetDevGenNames[type].mutex);
+}
diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h
index 53e606c6..19f37b61 100644
--- a/src/util/virnetdev.h
+++ b/src/util/virnetdev.h
@@ -40,6 +40,12 @@ typedef void virIfreq;
*/
#define VIR_NET_GENERATED_TAP_PREFIX "vnet"
+/* libvirt will start macvtap/macvlan interface names with one of
+ * these prefixes when it auto-generates the name
+ */
+#define VIR_NET_GENERATED_MACVTAP_PREFIX "macvtap"
+#define VIR_NET_GENERATED_MACVLAN_PREFIX "macvlan"
+
typedef enum {
VIR_NETDEV_RX_FILTER_MODE_NONE = 0,
VIR_NETDEV_RX_FILTER_MODE_NORMAL,
@@ -145,6 +151,24 @@ struct _virNetDevCoalesce {
uint32_t rate_sample_interval;
};
+typedef enum {
+ VIR_NET_DEV_GEN_NAME_NONE = 0,
+ VIR_NET_DEV_GEN_NAME_TAP,
+ VIR_NET_DEV_GEN_NAME_MACVTAP,
+ VIR_NET_DEV_GEN_NAME_MACVLAN,
+ VIR_NET_DEV_GEN_NAME_LAST
+} virNetDevGenNameType;
+
+VIR_ENUM_DECL(virNetDevGenNameType);
+
+typedef struct _virNetDevGenName virNetDevGenName;
+typedef virNetDevGenName *virNetDevGenNamePtr;
+struct _virNetDevGenName {
+ int lastID; /* not "unsigned" because callers use %d */
+ const char *prefix;
+ virMutex mutex;
+};
+
int virNetDevSetupControl(const char *ifname,
virIfreq *ifr)
@@ -321,3 +345,12 @@ int virNetDevVFInterfaceStats(virPCIDeviceAddressPtr vfAddr,
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
G_DEFINE_AUTOPTR_CLEANUP_FUNC(virNetDevRxFilter, virNetDevRxFilterFree);
+
+void virNetDevReserveName(const char *name,
+ virNetDevGenNameType type,
+ bool locked);
+
+int virNetDevGenerateName(char **ifname, virNetDevGenNameType type);
+
+void virNetDevLockGenName(virNetDevGenNameType type);
+void virNetDevUnlockGenName(virNetDevGenNameType type);
--
2.25.1
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