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SubjectRe: [PATCH 4.19 001/125] bonding: fix state transition issue in link monitoring
On Tue, Nov 12, 2019 at 3:05 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> From: Jay Vosburgh <jay.vosburgh@canonical.com>
>
> [ Upstream commit 1899bb325149e481de31a4f32b59ea6f24e176ea ]
>
> Since de77ecd4ef02 ("bonding: improve link-status update in
> mii-monitoring"), the bonding driver has utilized two separate variables
> to indicate the next link state a particular slave should transition to.
> Each is used to communicate to a different portion of the link state
> change commit logic; one to the bond_miimon_commit function itself, and
> another to the state transition logic.
>
> Unfortunately, the two variables can become unsynchronized,
> resulting in incorrect link state transitions within bonding. This can
> cause slaves to become stuck in an incorrect link state until a
> subsequent carrier state transition.
>
> The issue occurs when a special case in bond_slave_netdev_event
> sets slave->link directly to BOND_LINK_FAIL. On the next pass through
> bond_miimon_inspect after the slave goes carrier up, the BOND_LINK_FAIL
> case will set the proposed next state (link_new_state) to BOND_LINK_UP,
> but the new_link to BOND_LINK_DOWN. The setting of the final link state
> from new_link comes after that from link_new_state, and so the slave
> will end up incorrectly in _DOWN state.
>
> Resolve this by combining the two variables into one.
>
> Reported-by: Aleksei Zakharov <zakharov.a.g@yandex.ru>
> Reported-by: Sha Zhang <zhangsha.zhang@huawei.com>
> Cc: Mahesh Bandewar <maheshb@google.com>
> Fixes: de77ecd4ef02 ("bonding: improve link-status update in mii-monitoring")
> Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> drivers/net/bonding/bond_main.c | 41 +++++++++++++++++++---------------------
> include/net/bonding.h | 3 --
> 2 files changed, 21 insertions(+), 23 deletions(-)
>
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -2074,8 +2074,7 @@ static int bond_miimon_inspect(struct bo
> ignore_updelay = !rcu_dereference(bond->curr_active_slave);
>
> bond_for_each_slave_rcu(bond, slave, iter) {
> - slave->new_link = BOND_LINK_NOCHANGE;
> - slave->link_new_state = slave->link;
> + bond_propose_link_state(slave, BOND_LINK_NOCHANGE);
>
> link_state = bond_check_dev_link(bond, slave->dev, 0);
>
> @@ -2111,7 +2110,7 @@ static int bond_miimon_inspect(struct bo
> }
>
> if (slave->delay <= 0) {
> - slave->new_link = BOND_LINK_DOWN;
> + bond_propose_link_state(slave, BOND_LINK_DOWN);
> commit++;
> continue;
> }
> @@ -2150,7 +2149,7 @@ static int bond_miimon_inspect(struct bo
> slave->delay = 0;
>
> if (slave->delay <= 0) {
> - slave->new_link = BOND_LINK_UP;
> + bond_propose_link_state(slave, BOND_LINK_UP);
> commit++;
> ignore_updelay = false;
> continue;
> @@ -2188,7 +2187,7 @@ static void bond_miimon_commit(struct bo
> struct slave *slave, *primary;
>
> bond_for_each_slave(bond, slave, iter) {
> - switch (slave->new_link) {
> + switch (slave->link_new_state) {
> case BOND_LINK_NOCHANGE:
> /* For 802.3ad mode, check current slave speed and
> * duplex again in case its port was disabled after
> @@ -2263,8 +2262,8 @@ static void bond_miimon_commit(struct bo
>
> default:
> netdev_err(bond->dev, "invalid new link %d on slave %s\n",
> - slave->new_link, slave->dev->name);
> - slave->new_link = BOND_LINK_NOCHANGE;
> + slave->link_new_state, slave->dev->name);
> + bond_propose_link_state(slave, BOND_LINK_NOCHANGE);
>
> continue;
> }
> @@ -2664,13 +2663,13 @@ static void bond_loadbalance_arp_mon(str
> bond_for_each_slave_rcu(bond, slave, iter) {
> unsigned long trans_start = dev_trans_start(slave->dev);
>
> - slave->new_link = BOND_LINK_NOCHANGE;
> + bond_propose_link_state(slave, BOND_LINK_NOCHANGE);
>
> if (slave->link != BOND_LINK_UP) {
> if (bond_time_in_interval(bond, trans_start, 1) &&
> bond_time_in_interval(bond, slave->last_rx, 1)) {
>
> - slave->new_link = BOND_LINK_UP;
> + bond_propose_link_state(slave, BOND_LINK_UP);
> slave_state_changed = 1;
>
> /* primary_slave has no meaning in round-robin
> @@ -2697,7 +2696,7 @@ static void bond_loadbalance_arp_mon(str
> if (!bond_time_in_interval(bond, trans_start, 2) ||
> !bond_time_in_interval(bond, slave->last_rx, 2)) {
>
> - slave->new_link = BOND_LINK_DOWN;
> + bond_propose_link_state(slave, BOND_LINK_DOWN);
> slave_state_changed = 1;
>
> if (slave->link_failure_count < UINT_MAX)
> @@ -2729,8 +2728,8 @@ static void bond_loadbalance_arp_mon(str
> goto re_arm;
>
> bond_for_each_slave(bond, slave, iter) {
> - if (slave->new_link != BOND_LINK_NOCHANGE)
> - slave->link = slave->new_link;
> + if (slave->link_new_state != BOND_LINK_NOCHANGE)
> + slave->link = slave->link_new_state;
> }
>
> if (slave_state_changed) {
> @@ -2753,9 +2752,9 @@ re_arm:
> }
>
> /* Called to inspect slaves for active-backup mode ARP monitor link state
> - * changes. Sets new_link in slaves to specify what action should take
> - * place for the slave. Returns 0 if no changes are found, >0 if changes
> - * to link states must be committed.
> + * changes. Sets proposed link state in slaves to specify what action
> + * should take place for the slave. Returns 0 if no changes are found, >0
> + * if changes to link states must be committed.
> *
> * Called with rcu_read_lock held.
> */
> @@ -2767,12 +2766,12 @@ static int bond_ab_arp_inspect(struct bo
> int commit = 0;
>
> bond_for_each_slave_rcu(bond, slave, iter) {
> - slave->new_link = BOND_LINK_NOCHANGE;
> + bond_propose_link_state(slave, BOND_LINK_NOCHANGE);
> last_rx = slave_last_rx(bond, slave);
>
> if (slave->link != BOND_LINK_UP) {
> if (bond_time_in_interval(bond, last_rx, 1)) {
> - slave->new_link = BOND_LINK_UP;
> + bond_propose_link_state(slave, BOND_LINK_UP);
> commit++;
> }
> continue;
> @@ -2800,7 +2799,7 @@ static int bond_ab_arp_inspect(struct bo
> if (!bond_is_active_slave(slave) &&
> !rcu_access_pointer(bond->current_arp_slave) &&
> !bond_time_in_interval(bond, last_rx, 3)) {
> - slave->new_link = BOND_LINK_DOWN;
> + bond_propose_link_state(slave, BOND_LINK_DOWN);
> commit++;
> }
>
> @@ -2813,7 +2812,7 @@ static int bond_ab_arp_inspect(struct bo
> if (bond_is_active_slave(slave) &&
> (!bond_time_in_interval(bond, trans_start, 2) ||
> !bond_time_in_interval(bond, last_rx, 2))) {
> - slave->new_link = BOND_LINK_DOWN;
> + bond_propose_link_state(slave, BOND_LINK_DOWN);
> commit++;
> }
> }
> @@ -2833,7 +2832,7 @@ static void bond_ab_arp_commit(struct bo
> struct slave *slave;
>
> bond_for_each_slave(bond, slave, iter) {
> - switch (slave->new_link) {
> + switch (slave->link_new_state) {
> case BOND_LINK_NOCHANGE:
> continue;
>
> @@ -2886,7 +2885,7 @@ static void bond_ab_arp_commit(struct bo
>
> default:
> netdev_err(bond->dev, "impossible: new_link %d on slave %s\n",

Hello,

I think the error message here should be: "impossible: link_new_state
%d on slave %s\n" instead?
As in the upstream commit it's:
slave_err(bond->dev, slave->dev,
"impossible: link_new_state %d on slave\n",
slave->link_new_state);

Thanks




> - slave->new_link, slave->dev->name);
> + slave->link_new_state, slave->dev->name);
> continue;
> }
>
> --- a/include/net/bonding.h
> +++ b/include/net/bonding.h
> @@ -149,7 +149,6 @@ struct slave {
> unsigned long target_last_arp_rx[BOND_MAX_ARP_TARGETS];
> s8 link; /* one of BOND_LINK_XXXX */
> s8 link_new_state; /* one of BOND_LINK_XXXX */
> - s8 new_link;
> u8 backup:1, /* indicates backup slave. Value corresponds with
> BOND_STATE_ACTIVE and BOND_STATE_BACKUP */
> inactive:1, /* indicates inactive slave */
> @@ -539,7 +538,7 @@ static inline void bond_propose_link_sta
>
> static inline void bond_commit_link_state(struct slave *slave, bool notify)
> {
> - if (slave->link == slave->link_new_state)
> + if (slave->link_new_state == BOND_LINK_NOCHANGE)
> return;
>
> slave->link = slave->link_new_state;
>
>

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