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netdevtap: Use common helper function to create unique tap name

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Simplify GenerateName/ReserveName for netdevtap by using common
functions.

Signed-off-by: Shi Lei <shi_lei@massclouds.com>
Reviewed-by: Laine Stump <laine@redhat.com>
This commit is contained in:
Shi Lei 2020-12-14 09:50:33 +08:00 committed by Laine Stump
parent 294fd4bd80
commit c36cad1a31
4 changed files with 5 additions and 102 deletions

1
src/libvirt_private.syms

@ -2692,7 +2692,6 @@ virNetDevTapGetName;
virNetDevTapGetRealDeviceName;
virNetDevTapInterfaceStats;
virNetDevTapReattachBridge;
virNetDevTapReserveName;
# util/virnetdevveth.h

2
src/qemu/qemu_process.c

@ -3396,7 +3396,7 @@ qemuProcessNotifyNets(virDomainDefPtr def)
case VIR_DOMAIN_NET_TYPE_BRIDGE:
case VIR_DOMAIN_NET_TYPE_NETWORK:
case VIR_DOMAIN_NET_TYPE_ETHERNET:
virNetDevTapReserveName(net->ifname);
virNetDevReserveName(net->ifname);
break;
case VIR_DOMAIN_NET_TYPE_USER:
case VIR_DOMAIN_NET_TYPE_VHOSTUSER:

100
src/util/virnetdevtap.c

@ -49,51 +49,11 @@
#if defined(WITH_GETIFADDRS) && defined(AF_LINK)
# include <ifaddrs.h>
#endif
#include <math.h>
#define VIR_FROM_THIS VIR_FROM_NONE
VIR_LOG_INIT("util.netdevtap");
virMutex virNetDevTapCreateMutex = VIR_MUTEX_INITIALIZER;
static int virNetDevTapLastID = -1; /* not "unsigned" because callers use %d */
/**
* virNetDevTapReserveName:
* @name: name of an existing tap device
*
* Set the value of virNetDevTapLastID to assure that any new tap
* device created with an autogenerated name will use a number higher
* than the number in the given tap device name.
*
* Returns nothing.
*/
void
virNetDevTapReserveName(const char *name)
{
unsigned int id;
const char *idstr = NULL;
if (STRPREFIX(name, VIR_NET_GENERATED_VNET_PREFIX)) {
VIR_INFO("marking device in use: '%s'", name);
idstr = name + strlen(VIR_NET_GENERATED_VNET_PREFIX);
if (virStrToLong_ui(idstr, NULL, 10, &id) >= 0) {
virMutexLock(&virNetDevTapCreateMutex);
if (virNetDevTapLastID < (int)id)
virNetDevTapLastID = id;
virMutexUnlock(&virNetDevTapCreateMutex);
}
}
}
/**
* virNetDevTapGetName:
* @tapfd: a tun/tap file descriptor
@ -183,55 +143,6 @@ virNetDevTapGetRealDeviceName(char *ifname G_GNUC_UNUSED)
#ifdef TUNSETIFF
/**
* virNetDevTapGenerateName:
* @ifname: pointer to pointer to string containing template
*
* generate a new (currently unused) name for a new tap device based
* on the templace string in @ifname - replace %d with
* ++virNetDevTapLastID, 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.
*/
static int
virNetDevTapGenerateName(char **ifname)
{
int id;
double maxIDd = pow(10, IFNAMSIZ - 1 - strlen(VIR_NET_GENERATED_VNET_PREFIX));
int maxID = INT_MAX;
int attempts = 0;
if (maxIDd <= (double)INT_MAX)
maxID = (int)maxIDd;
do {
g_autofree char *try = NULL;
id = ++virNetDevTapLastID;
/* reset before overflow */
if (virNetDevTapLastID >= maxID)
virNetDevTapLastID = -1;
try = g_strdup_printf(*ifname, 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"),
VIR_NET_GENERATED_VNET_PREFIX);
return -1;
}
/**
* virNetDevTapCreate:
* @ifname: the interface name
@ -263,16 +174,14 @@ int virNetDevTapCreate(char **ifname,
int ret = -1;
int fd = -1;
virMutexLock(&virNetDevTapCreateMutex);
/* if ifname is "vnet%d", then auto-generate a name for the new
* device (the kernel could do this for us, but has a bad habit of
* immediately re-using names that have just been released, which
* can lead to race conditions).
*/
if (STREQ(*ifname, VIR_NET_GENERATED_VNET_PREFIX "%d") &&
virNetDevTapGenerateName(ifname) < 0) {
goto cleanup;
* if ifname is just a user-provided name, virNetDevGenerateName
* leaves it unchanged. */
if (virNetDevGenerateName(ifname, VIR_NET_DEV_GEN_NAME_VNET) < 0) {
return -1;
}
if (!tunpath)
@ -333,7 +242,6 @@ int virNetDevTapCreate(char **ifname,
ret = 0;
cleanup:
virMutexUnlock(&virNetDevTapCreateMutex);
if (ret < 0) {
VIR_FORCE_CLOSE(fd);
while (i--)

4
src/util/virnetdevtap.h

@ -29,10 +29,6 @@
# define VIR_NETDEV_TAP_REQUIRE_MANUAL_CLEANUP 1
#endif
void
virNetDevTapReserveName(const char *name)
ATTRIBUTE_NONNULL(1);
int virNetDevTapCreate(char **ifname,
const char *tunpath,
int *tapfd,