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platform: try harder to get the genl family ID by getting it synchronously

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We now cache the family ID for generic netlink protocols. However,
when we for example create a wireguard interface, the kernel module
might just get autoloaded. At this point, we didn't know the family ID
yet.

We already made an effort, that if the family ID is unknown during
nm_platform_genl_get_family_id(), we would try to poll the genl socket
in the hope there is a relevant event there. However, polling the socket
also means to potentially emit all signals for any change that happen.
We don't want that, if we currently are already polling the socket.

Instead, fallback to synchronously get the family ID.

  $ sudo rmmod wireguard \
    ./tools/run-nm-test.sh -m src/core/platform/tests/test-link-linux -p /link/software/detect/wireguard/1/external

Fixes: 3d4906a3da ('platform: add genl socket support for events and genl family')
This commit is contained in:
Thomas Haller
2022-07-20 13:43:22 +02:00
parent 571f3c57bd
commit e9f6e0abe1
1 changed files with 41 additions and 15 deletions
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56
src/libnm-platform/nm-linux-platform.c
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@@ -9393,10 +9393,27 @@ tfilter_delete(NMPlatform *platform, int ifindex, guint32 parent, gboolean log_e
/*****************************************************************************/
static gboolean
_genl_family_id_update(NMPlatform *platform, NMPGenlFamilyType family_type, guint16 family_id)
{
NMLinuxPlatformPrivate *priv = NM_LINUX_PLATFORM_GET_PRIVATE(platform);
if (priv->genl_family_data[family_type].family_id == family_id)
return FALSE;
if (family_id != 0) {
_LOGD("genl:ctrl: new family-id for %s: 0x%04x",
nmp_genl_family_infos[family_type].name,
family_id);
} else
_LOGD("genl:ctrl: del family-id for %s", nmp_genl_family_infos[family_type].name);
priv->genl_family_data[family_type].family_id = family_id;
return TRUE;
}
static void
_genl_handle_msg_ctrl(NMPlatform *platform, const struct nlmsghdr *hdr)
{
NMLinuxPlatformPrivate *priv = NM_LINUX_PLATFORM_GET_PRIVATE(platform);
const struct genlmsghdr *ghdr = nlmsg_data(hdr);
switch (ghdr->cmd) {
@@ -9420,13 +9437,7 @@ _genl_handle_msg_ctrl(NMPlatform *platform, const struct nlmsghdr *hdr)
if (ghdr->cmd == CTRL_CMD_NEWFAMILY)
family_id = nla_get_u16(tb[CTRL_ATTR_FAMILY_ID]);
if (priv->genl_family_data[family_type].family_id != family_id) {
if (family_id != 0)
_LOGD("genl:ctrl: new family-id for %s: 0x%04x", name, family_id);
else
_LOGD("genl:ctrl: del family-id for %s", name);
priv->genl_family_data[family_type].family_id = family_id;
}
_genl_family_id_update(platform, family_type, family_id);
}
}
}
@@ -9861,18 +9872,33 @@ static guint16
genl_get_family_id(NMPlatform *platform, NMPGenlFamilyType family_type)
{
NMLinuxPlatformPrivate *priv = NM_LINUX_PLATFORM_GET_PRIVATE(platform);
int family_id;
nm_assert(_NM_INT_NOT_NEGATIVE(family_type));
nm_assert(family_type < G_N_ELEMENTS(priv->genl_family_data));
if (priv->genl_family_data[family_type].family_id == 0) {
/* Unknown family ID. Try to read the netlink socket, maybe we have
* a message there to learn it. */
delayed_action_schedule(platform, DELAYED_ACTION_TYPE_READ_GENL, NULL);
if (priv->delayed_action.is_handling == 0)
delayed_action_handle_all(platform);
}
if (priv->genl_family_data[family_type].family_id != 0)
goto out;
/* Unknown family ID... usually we expect to start using the protocol.
* Let's try harder and fetch the ID synchronously.
*
* Note that we might also be called back during delayed_action_handle_all(),
* when we add a WireGuard link, the module gets autoloaded, and we didn't
* yet process the genl notification about the new family. Let's not call
* delayed_action_handle_all() again, because that might emit various
* signals. */
family_id = genl_ctrl_resolve(priv->sk_genl_sync, nmp_genl_family_infos[family_type].name);
if (family_id < 0)
family_id = 0;
/* We cache the family ID and update it via genl notifications.
* Here we bypass the order of that, and update the cached value
* directly. */
_genl_family_id_update(platform, family_type, family_id);
out:
return priv->genl_family_data[family_type].family_id;
}