Attempt to resume a previously deactivated target when the associated interface comes back (NETDEV_UP event is received) by calling __netpoll_setup_hold on the device.
For targets that were initally setup by mac address, their address is also compared with the interface address (while still verifying that the interface name matches). __netpoll_setup_hold assumes RTNL is held (which is guaranteed to be the case when handling the event) and holds a reference to the device in case of success. This reference will be removed upon target (or netconsole) removal by netpoll_cleanup. Target transitions to STATE_DISABLED in case of failures resuming it to avoid retrying the same target indefinitely. Signed-off-by: Andre Carvalho <[email protected]> --- drivers/net/netconsole.c | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 59d770bb4baa5f9616b10c0dfb39ed45a4eb7710..96485e979e61e0ed6c850ae3b29f46d529923f2d 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -135,10 +135,12 @@ enum target_state { * @stats: Packet send stats for the target. Used for debugging. * @state: State of the target. * Visible from userspace (read-write). - * We maintain a strict 1:1 correspondence between this and - * whether the corresponding netpoll is active or inactive. + * From a userspace perspective, the target is either enabled or + * disabled. Internally, although both STATE_DISABLED and + * STATE_DEACTIVATED correspond to inactive netpoll the latter is + * due to interface state changes and may recover automatically. * Also, other parameters of a target may be modified at - * runtime only when it is disabled (state == STATE_DISABLED). + * runtime only when it is disabled (state != STATE_ENABLED). * @extended: Denotes whether console is extended or not. * @release: Denotes whether kernel release version should be prepended * to the message. Depends on extended console. @@ -1430,6 +1432,31 @@ static int prepare_extradata(struct netconsole_target *nt) } #endif /* CONFIG_NETCONSOLE_DYNAMIC */ +/* Attempts to resume logging to a deactivated target. */ +static void maybe_resume_target(struct netconsole_target *nt, + struct net_device *ndev) +{ + int ret; + + if (strncmp(nt->np.dev_name, ndev->name, IFNAMSIZ)) + return; + + /* for targets specified by mac, also verify it matches the addr */ + if (!is_broadcast_ether_addr(nt->np.dev_mac) && + memcmp(nt->np.dev_mac, ndev->dev_addr, ETH_ALEN)) + return; + + ret = __netpoll_setup_hold(&nt->np, ndev); + if (ret) { + /* netpoll fails setup once, do not try again. */ + nt->state = STATE_DISABLED; + } else { + nt->state = STATE_ENABLED; + pr_info("network logging resumed on interface %s\n", + nt->np.dev_name); + } +} + /* Handle network interface device notifications */ static int netconsole_netdev_event(struct notifier_block *this, unsigned long event, void *ptr) @@ -1440,7 +1467,8 @@ static int netconsole_netdev_event(struct notifier_block *this, bool stopped = false; if (!(event == NETDEV_CHANGENAME || event == NETDEV_UNREGISTER || - event == NETDEV_RELEASE || event == NETDEV_JOIN)) + event == NETDEV_RELEASE || event == NETDEV_JOIN || + event == NETDEV_UP)) goto done; mutex_lock(&target_cleanup_list_lock); @@ -1460,6 +1488,8 @@ static int netconsole_netdev_event(struct notifier_block *this, stopped = true; } } + if (nt->state == STATE_DEACTIVATED && event == NETDEV_UP) + maybe_resume_target(nt, dev); netconsole_target_put(nt); } spin_unlock_irqrestore(&target_list_lock, flags); -- 2.51.0
