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util: keep/use a bitmap of in-use macvtap devices

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This patch creates two bitmaps, one for macvlan device names and one
for macvtap. The bitmap position is used to indicate that libvirt is
currently using a device with the name macvtap%d/macvlan%d, where %d
is the position in the bitmap. When requested to create a new
macvtap/macvlan device, libvirt will now look for the first clear bit
in the appropriate bitmap and derive the device name from that rather
than just starting at 0 and counting up until one works.

When libvirtd is restarted, the qemu driver code that reattaches to
active domains calls the appropriate function to "re-reserve" the
device names as it is scanning the status of running domains.

Note that it may seem strange that the retry counter now starts at
8191 instead of 5. This is because we now don't do a "pre-check" for
the existence of a device once we've reserved it in the bitmap - we
move straight to creating it; although very unlikely, it's possible
that someone has a running system where they have a large number of
network devices *created outside libvirt* named "macvtap%d" or
"macvlan%d" - such a setup would still allow creating more devices
with the old code, while a low retry max in the new code would cause a
failure. Since the objective of the retry max is just to prevent an
infinite loop, and it's highly unlikely to do more than 1 iteration
anyway, having a high max is a reasonable concession in order to
prevent lots of new failures.
This commit is contained in:
Laine Stump 2016-01-19 14:20:54 -05:00
parent 8c70d04bab
commit 370608b4c7
4 changed files with 336 additions and 68 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/libvirt_private.syms
View File

@ -1853,6 +1853,8 @@ virNetDevMacVLanCreate;
virNetDevMacVLanCreateWithVPortProfile;
virNetDevMacVLanDelete;
virNetDevMacVLanDeleteWithVPortProfile;
virNetDevMacVLanReleaseName;
virNetDevMacVLanReserveName;
virNetDevMacVLanRestartWithVPortProfile;
virNetDevMacVLanVPortProfileRegisterCallback;

10
src/qemu/qemu_process.c
View File

@ -1,7 +1,7 @@
/*
* qemu_process.c: QEMU process management
*
* Copyright (C) 2006-2015 Red Hat, Inc.
* Copyright (C) 2006-2016 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@ -3161,6 +3161,14 @@ qemuProcessNotifyNets(virDomainDefPtr def)
for (i = 0; i < def->nnets; i++) {
virDomainNetDefPtr net = def->nets[i];
/* keep others from trying to use the macvtap device name, but
* don't return error if this happens, since that causes the
* domain to be unceremoniously killed, which would be *very*
* impolite.
*/
if (virDomainNetGetActualType(net) == VIR_DOMAIN_NET_TYPE_DIRECT)
ignore_value(virNetDevMacVLanReserveName(net->ifname, false));
if (networkNotifyActualDevice(def, net) < 0)
return -1;
}

387
src/util/virnetdevmacvlan.c
View File

@ -1,5 +1,5 @@
/*
* Copyright (C) 2010-2015 Red Hat, Inc.
* Copyright (C) 2010-2016 Red Hat, Inc.
* Copyright (C) 2010-2012 IBM Corporation
*
* This library is free software; you can redistribute it and/or
@ -64,6 +64,7 @@ VIR_ENUM_IMPL(virNetDevMacVLanMode, VIR_NETDEV_MACVLAN_MODE_LAST,
# include "virnetlink.h"
# include "virnetdev.h"
# include "virpidfile.h"
# include "virbitmap.h"
VIR_LOG_INIT("util.netdevmacvlan");
@ -73,7 +74,226 @@ VIR_LOG_INIT("util.netdevmacvlan");
# define MACVLAN_NAME_PREFIX "macvlan"
# define MACVLAN_NAME_PATTERN "macvlan%d"
# define MACVLAN_MAX_ID 8191
virMutex virNetDevMacVLanCreateMutex = VIR_MUTEX_INITIALIZER;
virBitmapPtr macvtapIDs = NULL;
virBitmapPtr macvlanIDs = NULL;
static int
virNetDevMacVLanOnceInit(void)
{
if (!macvtapIDs &&
!(macvtapIDs = virBitmapNew(MACVLAN_MAX_ID + 1)))
return -1;
if (!macvlanIDs &&
!(macvlanIDs = virBitmapNew(MACVLAN_MAX_ID + 1)))
return -1;
return 0;
}
VIR_ONCE_GLOBAL_INIT(virNetDevMacVLan);
/**
* virNetDevMacVLanReserveID:
*
* @id: id 0 - MACVLAN_MAX_ID+1 to reserve (or -1 for "first free")
* @flags: set VIR_NETDEV_MACVLAN_CREATE_WITH_TAP for macvtapN else macvlanN
* @quietFail: don't log an error if this name is already in-use
* @nextFree: reserve the next free ID *after* @id rather than @id itself
*
* Reserve the indicated ID in the appropriate bitmap, or find the
* first free ID if @id is -1.
*
* Returns newly reserved ID# on success, or -1 to indicate failure.
*/
static int
virNetDevMacVLanReserveID(int id, unsigned int flags,
bool quietFail, bool nextFree)
{
virBitmapPtr bitmap;
if (virNetDevMacVLanInitialize() < 0)
return -1;
bitmap = (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
macvtapIDs : macvlanIDs;
if (id > MACVLAN_MAX_ID) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("can't use name %s%d - out of range 0-%d"),
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX,
id, MACVLAN_MAX_ID);
return -1;
}
if ((id < 0 || nextFree) &&
(id = virBitmapNextClearBit(bitmap, 0)) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("no unused %s names available"),
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX);
return -1;
}
if (virBitmapIsBitSet(bitmap, id)) {
if (quietFail) {
VIR_INFO("couldn't reserve name %s%d - already in use",
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX, id);
} else {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("couldn't reserve name %s%d - already in use"),
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX, id);
}
return -1;
}
if (virBitmapSetBit(bitmap, id) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("couldn't mark %s%d as used"),
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX, id);
return -1;
}
VIR_INFO("reserving device %s%d",
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX, id);
return id;
}
/**
* virNetDevMacVLanReleaseID:
* @id: id 0 - MACVLAN_MAX_ID+1 to release
*
* Returns 0 for success or -1 for failure.
*/
static int
virNetDevMacVLanReleaseID(int id, unsigned int flags)
{
virBitmapPtr bitmap;
if (virNetDevMacVLanInitialize() < 0)
return 0;
bitmap = (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
macvtapIDs : macvlanIDs;
if (id > MACVLAN_MAX_ID) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("can't free name %s%d - out of range 0-%d"),
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX,
id, MACVLAN_MAX_ID);
return -1;
}
if (id < 0)
return 0;
VIR_INFO("releasing %sdevice %s%d",
virBitmapIsBitSet(bitmap, id) ? "" : "unreserved",
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX, id);
if (virBitmapClearBit(bitmap, id) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("couldn't mark %s%d as unused"),
(flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX, id);
return -1;
}
return 0;
}
/**
* virNetDevMacVLanReserveName:
*
* @name: already-known name of device
* @quietFail: don't log an error if this name is already in-use
*
* Extract the device type and id from a macvtap/macvlan device name
* and mark the appropriate position as in-use in the appropriate
* bitmap.
*
* Returns reserved ID# on success, -1 on failure, -2 if the name
* doesn't fit the auto-pattern (so not reserveable).
*/
int
virNetDevMacVLanReserveName(const char *name, bool quietFail)
{
unsigned int id;
unsigned int flags = 0;
const char *idstr = NULL;
if (virNetDevMacVLanInitialize() < 0)
return -1;
if (STRPREFIX(name, MACVTAP_NAME_PREFIX)) {
idstr = name + strlen(MACVTAP_NAME_PREFIX);
flags |= VIR_NETDEV_MACVLAN_CREATE_WITH_TAP;
} else if (STRPREFIX(name, MACVLAN_NAME_PREFIX)) {
idstr = name + strlen(MACVLAN_NAME_PREFIX);
} else {
return -2;
}
if (virStrToLong_ui(idstr, NULL, 10, &id) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("couldn't get id value from macvtap device name %s"),
name);
return -1;
}
return virNetDevMacVLanReserveID(id, flags, quietFail, false);
}
/**
* virNetDevMacVLanReleaseName:
*
* @name: already-known name of device
*
* Extract the device type and id from a macvtap/macvlan device name
* and mark the appropriate position as in-use in the appropriate
* bitmap.
*
* returns 0 on success, -1 on failure
*/
int
virNetDevMacVLanReleaseName(const char *name)
{
unsigned int id;
unsigned int flags = 0;
const char *idstr = NULL;
if (virNetDevMacVLanInitialize() < 0)
return -1;
if (STRPREFIX(name, MACVTAP_NAME_PREFIX)) {
idstr = name + strlen(MACVTAP_NAME_PREFIX);
flags |= VIR_NETDEV_MACVLAN_CREATE_WITH_TAP;
} else if (STRPREFIX(name, MACVLAN_NAME_PREFIX)) {
idstr = name + strlen(MACVLAN_NAME_PREFIX);
} else {
return 0;
}
if (virStrToLong_ui(idstr, NULL, 10, &id) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("couldn't get id value from macvtap device name %s"),
name);
return -1;
}
return virNetDevMacVLanReleaseID(id, flags);
}
/**
* virNetDevMacVLanCreate:
@ -724,14 +944,20 @@ virNetDevMacVLanVPortProfileRegisterCallback(const char *ifname,
* virNetDevMacVLanCreateWithVPortProfile:
* Create an instance of a macvtap device and open its tap character
* device.
* @tgifname: Interface name that the macvtap is supposed to have. May
* be NULL if this function is supposed to choose a name
* @ifnameRequested: Interface name that the caller wants the macvtap
* device to have, or NULL to pick the first available name
* appropriate for the type (macvlan%d or macvtap%d). If the
* suggested name fits one of those patterns, but is already in
* use, we will fallback to finding the first available. If the
* suggested name *doesn't* fit a pattern and the name is in use,
* we will fail.
* @macaddress: The MAC address for the macvtap device
* @linkdev: The interface name of the NIC to connect to the external bridge
* @mode: int describing the mode for 'bridge', 'vepa', 'private' or 'passthru'.
* @mode: macvtap mode (VIR_NETDEV_MACVLAN_MODE_(BRIDGE|VEPA|PRIVATE|PASSTHRU)
* @vmuuid: The UUID of the VM the macvtap belongs to
* @virtPortProfile: pointer to object holding the virtual port profile data
* @res_ifname: Pointer to a string pointer where the actual name of the
* @ifnameResult: Pointer to a string pointer where the actual name of the
* interface will be stored into if everything succeeded. It is up
* to the caller to free the string.
* @tapfd: array of file descriptor return value for the new tap device
@ -744,39 +970,36 @@ virNetDevMacVLanVPortProfileRegisterCallback(const char *ifname,
*
* Return 0 on success, -1 on error.
*/
int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
const virMacAddr *macaddress,
const char *linkdev,
virNetDevMacVLanMode mode,
const unsigned char *vmuuid,
virNetDevVPortProfilePtr virtPortProfile,
char **res_ifname,
virNetDevVPortProfileOp vmOp,
char *stateDir,
int *tapfd,
size_t tapfdSize,
unsigned int flags)
int
virNetDevMacVLanCreateWithVPortProfile(const char *ifnameRequested,
const virMacAddr *macaddress,
const char *linkdev,
virNetDevMacVLanMode mode,
const unsigned char *vmuuid,
virNetDevVPortProfilePtr virtPortProfile,
char **ifnameResult,
virNetDevVPortProfileOp vmOp,
char *stateDir,
int *tapfd,
size_t tapfdSize,
unsigned int flags)
{
const char *type = (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
"macvtap" : "macvlan";
const char *prefix = (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PREFIX : MACVLAN_NAME_PREFIX;
const char *pattern = (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) ?
MACVTAP_NAME_PATTERN : MACVLAN_NAME_PATTERN;
int c, rc;
int rc, reservedID = -1;
char ifname[IFNAMSIZ];
int retries, do_retry = 0;
uint32_t macvtapMode;
const char *cr_ifname = NULL;
const char *ifnameCreated = NULL;
int ret;
int vf = -1;
bool vnet_hdr = flags & VIR_NETDEV_MACVLAN_VNET_HDR;
macvtapMode = modeMap[mode];
*res_ifname = NULL;
VIR_DEBUG("%s: VM OPERATION: %s", __FUNCTION__, virNetDevVPortProfileOpTypeToString(vmOp));
*ifnameResult = NULL;
/** Note: When using PASSTHROUGH mode with MACVTAP devices the link
* device's MAC address must be set to the VMs MAC address. In
@ -803,52 +1026,82 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
}
}
if (tgifname) {
if ((ret = virNetDevExists(tgifname)) < 0)
return -1;
if (ifnameRequested) {
bool isAutoName
= (STRPREFIX(ifnameRequested, MACVTAP_NAME_PREFIX) ||
STRPREFIX(ifnameRequested, MACVLAN_NAME_PREFIX));
VIR_INFO("Requested macvtap device name: %s", ifnameRequested);
virMutexLock(&virNetDevMacVLanCreateMutex);
if ((ret = virNetDevExists(ifnameRequested)) < 0) {
virMutexUnlock(&virNetDevMacVLanCreateMutex);
return -1;
}
if (ret) {
if (STRPREFIX(tgifname, prefix))
if (isAutoName)
goto create_name;
virReportSystemError(EEXIST,
_("Unable to create macvlan device %s"), tgifname);
_("Unable to create %s device %s"),
type, ifnameRequested);
virMutexUnlock(&virNetDevMacVLanCreateMutex);
return -1;
}
cr_ifname = tgifname;
rc = virNetDevMacVLanCreate(tgifname, type, macaddress, linkdev,
macvtapMode, &do_retry);
if (rc < 0)
if (isAutoName &&
(reservedID = virNetDevMacVLanReserveName(ifnameRequested, true)) < 0) {
reservedID = -1;
goto create_name;
}
if (virNetDevMacVLanCreate(ifnameRequested, type, macaddress,
linkdev, macvtapMode, &do_retry) < 0) {
if (isAutoName) {
virNetDevMacVLanReleaseName(ifnameRequested);
reservedID = -1;
goto create_name;
}
virMutexUnlock(&virNetDevMacVLanCreateMutex);
return -1;
} else {
}
/* virNetDevMacVLanCreate() was successful - use this name */
ifnameCreated = ifnameRequested;
create_name:
retries = 5;
virMutexLock(&virNetDevMacVLanCreateMutex);
for (c = 0; c < 8192; c++) {
snprintf(ifname, sizeof(ifname), pattern, c);
if ((ret = virNetDevExists(ifname)) < 0) {
virMutexUnlock(&virNetDevMacVLanCreateMutex);
return -1;
}
if (!ret) {
rc = virNetDevMacVLanCreate(ifname, type, macaddress, linkdev,
macvtapMode, &do_retry);
if (rc == 0) {
cr_ifname = ifname;
break;
}
if (do_retry && --retries)
continue;
break;
}
}
virMutexUnlock(&virNetDevMacVLanCreateMutex);
if (!cr_ifname)
return -1;
}
if (virNetDevVPortProfileAssociate(cr_ifname,
retries = MACVLAN_MAX_ID;
while (!ifnameCreated && retries) {
virMutexLock(&virNetDevMacVLanCreateMutex);
reservedID = virNetDevMacVLanReserveID(reservedID, flags, false, true);
if (reservedID < 0) {
virMutexUnlock(&virNetDevMacVLanCreateMutex);
return -1;
}
snprintf(ifname, sizeof(ifname), pattern, reservedID);
rc = virNetDevMacVLanCreate(ifname, type, macaddress, linkdev,
macvtapMode, &do_retry);
if (rc < 0) {
virNetDevMacVLanReleaseID(reservedID, flags);
virMutexUnlock(&virNetDevMacVLanCreateMutex);
if (!do_retry)
return -1;
VIR_INFO("Device %s wasn't reserved but already existed, skipping",
ifname);
retries--;
continue;
}
ifnameCreated = ifname;
virMutexUnlock(&virNetDevMacVLanCreateMutex);
}
if (!ifnameCreated) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Too many unreserved %s devices in use"),
type);
return -1;
}
if (virNetDevVPortProfileAssociate(ifnameCreated,
virtPortProfile,
macaddress,
linkdev,
@ -859,26 +1112,26 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
}
if (flags & VIR_NETDEV_MACVLAN_CREATE_IFUP) {
if (virNetDevSetOnline(cr_ifname, true) < 0) {
if (virNetDevSetOnline(ifnameCreated, true) < 0) {
rc = -1;
goto disassociate_exit;
}
}
if (flags & VIR_NETDEV_MACVLAN_CREATE_WITH_TAP) {
if (virNetDevMacVLanTapOpen(cr_ifname, tapfd, tapfdSize, 10) < 0)
if (virNetDevMacVLanTapOpen(ifnameCreated, tapfd, tapfdSize, 10) < 0)
goto disassociate_exit;
if (virNetDevMacVLanTapSetup(tapfd, tapfdSize, vnet_hdr) < 0) {
VIR_FORCE_CLOSE(rc); /* sets rc to -1 */
goto disassociate_exit;
}
if (VIR_STRDUP(*res_ifname, cr_ifname) < 0) {
if (VIR_STRDUP(*ifnameResult, ifnameCreated) < 0) {
VIR_FORCE_CLOSE(rc); /* sets rc to -1 */
goto disassociate_exit;
}
} else {
if (VIR_STRDUP(*res_ifname, cr_ifname) < 0)
if (VIR_STRDUP(*ifnameResult, ifnameCreated) < 0)
goto disassociate_exit;
rc = 0;
}
@ -889,7 +1142,7 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
* a saved image) - migration and libvirtd restart are handled
* elsewhere.
*/
if (virNetDevMacVLanVPortProfileRegisterCallback(cr_ifname, macaddress,
if (virNetDevMacVLanVPortProfileRegisterCallback(ifnameCreated, macaddress,
linkdev, vmuuid,
virtPortProfile,
vmOp) < 0)
@ -899,7 +1152,7 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
return rc;
disassociate_exit:
ignore_value(virNetDevVPortProfileDisassociate(cr_ifname,
ignore_value(virNetDevVPortProfileDisassociate(ifnameCreated,
virtPortProfile,
macaddress,
linkdev,
@ -909,7 +1162,8 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
VIR_FORCE_CLOSE(tapfd[tapfdSize]);
link_del_exit:
ignore_value(virNetDevMacVLanDelete(cr_ifname));
ignore_value(virNetDevMacVLanDelete(ifnameCreated));
virNetDevMacVLanReleaseName(ifnameCreated);
return rc;
}
@ -945,6 +1199,7 @@ int virNetDevMacVLanDeleteWithVPortProfile(const char *ifname,
ret = -1;
if (virNetDevMacVLanDelete(ifname) < 0)
ret = -1;
virNetDevMacVLanReleaseName(ifname);
}
if (mode == VIR_NETDEV_MACVLAN_MODE_PASSTHRU) {

5
src/util/virnetdevmacvlan.h
View File

@ -1,5 +1,5 @@
/*
* Copyright (C) 2011, 2013 Red Hat, Inc.
* Copyright (C) 2011, 2013, 2016 Red Hat, Inc.
* Copyright (C) 2010 IBM Corporation
*
* This library is free software; you can redistribute it and/or
@ -50,6 +50,9 @@ typedef enum {
VIR_NETDEV_MACVLAN_VNET_HDR = 1 << 2,
} virNetDevMacVLanCreateFlags;
int virNetDevMacVLanReserveName(const char *name, bool quietfail);
int virNetDevMacVLanReleaseName(const char *name);
int virNetDevMacVLanCreate(const char *ifname,
const char *type,
const virMacAddr *macaddress,