This patch creates two bitmaps, one for macvlan devicenames 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, qemu 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 8192 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. --- Changes from V1: * combine virNetDevMacVLanReserveNextFreeID() and virNetDevMacVLanReserveID() * put "macvlan" or "macvtap" into the "unable to create [blah] device "%s" as appropriate * eliminate redundant message when all device names are in use. (Background info that doesn't need to be in commit log: Tony Krowiak <akrowiak@linux.vnet.ibm.com> had pointed out here: https://www.redhat.com/archives/libvir-list/2015-October/msg00877.html that libvirt takes a *very long time* to creat macvtap/macvlan devices when there are a lot of them already in use. This is because the algorithm simply starts at macvtap0 and iterates calling virNetDevExists() for each possible name until it finds a free one. He had said at the time that he had tried keeping track of in-use macvtap/macvlan numbers in a bitmap, and had returns start time for a domain by 1m46s (from 2m to 14s) when there were 82 macvtap devices already in use. There was also an implication that he would post some patches for this to the list but, like all of us, apparently got busy with something else. Last week I ran into a situation where libvirt had created a macvtap device for a domain, and the domain was still using it, but for some reason the kernel (2.6.32-something on RHEL6) had lost track of that macvtap device, so when libvirt was asked to create a new macvtap device for another domain, it found that name to be "unused", and created a new device. The device creation was successful, but 802.1Qbh negotion failed. This failure was possibly because of the re-use of the macvtap name, possibly not, but the only way to find out was to not re-use the name. So lacking Tony's patches, I made my own and am posting them here. ) src/libvirt_private.syms | 2 + src/qemu/qemu_process.c | 10 +- src/util/virnetdevmacvlan.c | 380 ++++++++++++++++++++++++++++++++++++-------- src/util/virnetdevmacvlan.h | 5 +- 4 files changed, 332 insertions(+), 65 deletions(-) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 5e05a98..f08bd8c 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1851,6 +1851,8 @@ virNetDevMacVLanCreate; virNetDevMacVLanCreateWithVPortProfile; virNetDevMacVLanDelete; virNetDevMacVLanDeleteWithVPortProfile; +virNetDevMacVLanReleaseName; +virNetDevMacVLanReserveName; virNetDevMacVLanRestartWithVPortProfile; virNetDevMacVLanVPortProfileRegisterCallback; diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index d465b4f..31812f6 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -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; } diff --git a/src/util/virnetdevmacvlan.c b/src/util/virnetdevmacvlan.c index 98da009..fd168b7 100644 --- a/src/util/virnetdevmacvlan.c +++ b/src/util/virnetdevmacvlan.c @@ -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 +74,225 @@ 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 id 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 0 on success, -1 on failure, -2 if the name doesn't fit the auto-pattern + */ +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 +943,20 @@ 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 +969,36 @@ 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 +1025,82 @@ 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; + virMutexUnlock(&virNetDevMacVLanCreateMutex); + } + + retries = MACVLAN_MAX_ID + 1; + while (!ifnameCreated && retries) { virMutexLock(&virNetDevMacVLanCreateMutex); - for (c = 0; c < 8192; c++) { - snprintf(ifname, sizeof(ifname), pattern, c); - if ((ret = virNetDevExists(ifname)) < 0) { - virMutexUnlock(&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; - } - if (!ret) { - rc = virNetDevMacVLanCreate(ifname, type, macaddress, linkdev, - macvtapMode, &do_retry); - if (rc == 0) { - cr_ifname = ifname; - break; - } - - if (do_retry && --retries) - continue; - break; - } + VIR_INFO("Device %s wasn't reserved but already existed, skipping", + ifname); + retries--; + continue; } - + ifnameCreated = ifname; virMutexUnlock(&virNetDevMacVLanCreateMutex); - if (!cr_ifname) - return -1; } - if (virNetDevVPortProfileAssociate(cr_ifname, + 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 +1111,26 @@ 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 +1141,7 @@ 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 +1151,7 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname, return rc; disassociate_exit: - ignore_value(virNetDevVPortProfileDisassociate(cr_ifname, + ignore_value(virNetDevVPortProfileDisassociate(ifnameCreated, virtPortProfile, macaddress, linkdev, @@ -909,7 +1161,8 @@ 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 +1198,7 @@ int virNetDevMacVLanDeleteWithVPortProfile(const char *ifname, ret = -1; if (virNetDevMacVLanDelete(ifname) < 0) ret = -1; + virNetDevMacVLanReleaseName(ifname); } if (mode == VIR_NETDEV_MACVLAN_MODE_PASSTHRU) { diff --git a/src/util/virnetdevmacvlan.h b/src/util/virnetdevmacvlan.h index 70e3b01..560593e 100644 --- a/src/util/virnetdevmacvlan.h +++ b/src/util/virnetdevmacvlan.h @@ -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, -- 2.5.0