Re: [PATCH v4 net-next 5/6] net: dsa: mv88e6xxx: mac-auth/MAB implementation

netdev
2022-08-19T12:44:04Z

On 2022-07-17 02:47, Vladimir Oltean wrote:
>> @@ -1721,11 +1735,11 @@ static int mv88e6xxx_vtu_get(struct
>> mv88e6xxx_chip *chip, u16 vid,
>> return err;
>> }
>>
>> int mv88e6xxx_port_set_lock(struct mv88e6xxx_chip *chip, int port,
>> bool locked)
>> {
>> @@ -1257,13 +1270,18 @@ int mv88e6xxx_port_set_lock(struct
>> mv88e6xxx_chip *chip, int port,
>> if (err)
>> return err;
>>
>> - err = mv88e6xxx_port_read(chip, port, MV88E6XXX_PORT_ASSOC_VECTOR,
>> &reg);
>> - if (err)
>> - return err;
>> + if (!locked) {
>> + err = mv88e6xxx_atu_locked_entry_flush(chip->ds, port);
>
> Did you re-run the selftest with v4? Because this deadlocks due to the
> double reg_lock illustrated below:

I did some selftest, but I didn't experience the problem of the double
chip lock as it only happens on unlock which is only called where the
MAB test ends.

>
> + vrf_name=vlan1
> + ip vrf exec vlan1 ping 192.0.2.2 -c 10 -i 0.1 -w 5
> + check_err 1 'Ping did not work after locking port and adding FDB
> entry'
> + local err=1
> + local 'msg=Ping did not work after locking port and adding FDB entry'
> + [[ 0 -eq 0 ]]
> + [[ 1 -ne 0 ]]
> + RET=1
> + retmsg='Ping did not work after locking port and adding FDB entry'
> + bridge link set dev lan2 locked off
> [ 733.273994]
> [ 733.275515] ============================================
> [ 733.280823] WARNING: possible recursive locking detected
> [ 733.286133] 5.19.0-rc6-07010-ga9b9500ffaac-dirty #3293 Not tainted
> [ 733.292311] --------------------------------------------
> [ 733.297613] kworker/0:0/601 is trying to acquire lock:
> [ 733.302751] ffff00000213c110 (&chip->reg_lock){+.+.}-{4:4}, at:
> mv88e6xxx_atu_locked_entry_purge+0x70/0x1a4
> [ 733.312524]
> [ 733.312524] but task is already holding lock:
> [ 733.318351] ffff00000213c110 (&chip->reg_lock){+.+.}-{4:4}, at:
> mv88e6xxx_port_bridge_flags+0x48/0x234
> [ 733.327674]
> [ 733.327674] other info that might help us debug this:
> [ 733.334198] Possible unsafe locking scenario:
> [ 733.334198]
> [ 733.340109] CPU0
> [ 733.342549] ----
> [ 733.344990] lock(&chip->reg_lock);
> [ 733.348567] lock(&chip->reg_lock);
> [ 733.352149]
> [ 733.352149] *** DEADLOCK ***
> [ 733.352149]
> [ 733.358063] May be due to missing lock nesting notation
> [ 733.358063]
> [ 733.364846] 6 locks held by kworker/0:0/601:
> [ 733.369115] #0: ffff00000000b748
> ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1f4/0x6c4
> [ 733.378541] #1: ffff80000c43bdc8
> (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x1f4/0x6c4
> [ 733.387966] #2: ffff80000b020cb0 (rtnl_mutex){+.+.}-{4:4}, at:
> rtnl_lock+0x1c/0x30
> [ 733.395660] #3: ffff80000b073370
> ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at:
> blocking_notifier_call_chain+0x34/0xa0
> [ 733.407432] #4: ffff00000213c110 (&chip->reg_lock){+.+.}-{4:4},
> at: mv88e6xxx_port_bridge_flags+0x48/0x234
> [ 733.417202] #5: ffff00000213e0f0 (&p->ale_list_lock){+.+.}-{4:4},
> at: mv88e6xxx_atu_locked_entry_flush+0x4c/0xc0
> [ 733.427495]
> [ 733.427495] stack backtrace:
> [ 733.431858] CPU: 0 PID: 601 Comm: kworker/0:0 Not tainted
> 5.19.0-rc6-07010-ga9b9500ffaac-dirty #3293
> [ 733.440992] Hardware name: CZ.NIC Turris Mox Board (DT)
> [ 733.446219] Workqueue: events switchdev_deferred_process_work
> [ 733.451982] Call trace:
> [ 733.454424] dump_backtrace.part.0+0xcc/0xe0
> [ 733.458702] show_stack+0x18/0x6c
> [ 733.462028] dump_stack_lvl+0x8c/0xb8
> [ 733.465703] dump_stack+0x18/0x34
> [ 733.469029] __lock_acquire+0x1074/0x1fd0
> [ 733.473052] lock_acquire.part.0+0xe4/0x220
> [ 733.477244] lock_acquire+0x68/0x8c
> [ 733.480744] __mutex_lock+0x9c/0x460
> [ 733.484332] mutex_lock_nested+0x40/0x50
> [ 733.488268] mv88e6xxx_atu_locked_entry_purge+0x70/0x1a4
> [ 733.493592] mv88e6xxx_atu_locked_entry_flush+0x7c/0xc0
> [ 733.498827] mv88e6xxx_port_set_lock+0xfc/0x10c
> [ 733.503374] mv88e6xxx_port_bridge_flags+0x200/0x234
> [ 733.508351] dsa_port_bridge_flags+0x44/0xe0
> [ 733.512635] dsa_slave_port_attr_set+0x1ec/0x230
> [ 733.517268] __switchdev_handle_port_attr_set+0x58/0x100
> [ 733.522594] switchdev_handle_port_attr_set+0x10/0x24
> [ 733.527659] dsa_slave_switchdev_blocking_event+0x8c/0xd4
> [ 733.533074] blocking_notifier_call_chain+0x6c/0xa0
> [ 733.537968] switchdev_port_attr_notify.constprop.0+0x4c/0xb0
> [ 733.543729] switchdev_port_attr_set_deferred+0x24/0x80
> [ 733.548967] switchdev_deferred_process+0x90/0x164
> [ 733.553774] switchdev_deferred_process_work+0x14/0x2c
> [ 733.558926] process_one_work+0x28c/0x6c4
> [ 733.562949] worker_thread+0x74/0x450
> [ 733.566623] kthread+0x118/0x11c
> [ 733.569860] ret_from_fork+0x10/0x20
> ++ mac_get lan1
> ++ local if_name=lan1
> ++ jq -r '.[]["address"]'
> ++ ip -j link show dev lan1
>
> I've tentatively fixed this in my tree by taking the register lock more
> localized to the sub-functions of mv88e6xxx_port_bridge_flags(), and
> not
> taking it at caller side for mv88e6xxx_port_set_lock(), but rather
> letting the callee take it:

Yes, the double chip lock came from calling
mv88e6xxx_atu_locked_entry_flush() in mv88e6xxx_port_set_lock() that is
called from mv88e6xxx_port_bridge_flags() whic has the lock taken. I
have fixed this now, but when I unlock a port with locked entries, I
cannot have notify the bridge to clear the same locked entries by having
mv88e6xxx_atu_locked_entry_flush() calling with the notify on, thus
taking the rtnl lock, as this also results in a double lock.
To remove the locked entries in the bridge FDB it is then necessary as I
see it, to take the link down or have a userspace daemon clear them. I
hope that is okay if documented?

>
> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c
> b/drivers/net/dsa/mv88e6xxx/chip.c
> index 7b57ac121589..ec5954f32774 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -6557,41 +6557,47 @@ static int mv88e6xxx_port_bridge_flags(struct
> dsa_switch *ds, int port,
> struct mv88e6xxx_chip *chip = ds->priv;
> int err = -EOPNOTSUPP;
>
> - mv88e6xxx_reg_lock(chip);
> -
> if (flags.mask & BR_LEARNING) {
> bool learning = !!(flags.val & BR_LEARNING);
> u16 pav = learning ? (1 << port) : 0;
>
> + mv88e6xxx_reg_lock(chip);
> err = mv88e6xxx_port_set_assoc_vector(chip, port, pav);
> + mv88e6xxx_reg_unlock(chip);
> if (err)
> - goto out;
> + return err;
> }
>
> if (flags.mask & BR_FLOOD) {
> bool unicast = !!(flags.val & BR_FLOOD);
>
> + mv88e6xxx_reg_lock(chip);
> err = chip->info->ops->port_set_ucast_flood(chip, port,
> unicast);
> + mv88e6xxx_reg_unlock(chip);
> if (err)
> - goto out;
> + return err;
> }
>
> if (flags.mask & BR_MCAST_FLOOD) {
> bool multicast = !!(flags.val & BR_MCAST_FLOOD);
>
> + mv88e6xxx_reg_lock(chip);
> err = chip->info->ops->port_set_mcast_flood(chip, port,
> multicast);
> + mv88e6xxx_reg_unlock(chip);
> if (err)
> - goto out;
> + return err;
> }
>
> if (flags.mask & BR_BCAST_FLOOD) {
> bool broadcast = !!(flags.val & BR_BCAST_FLOOD);
>
> + mv88e6xxx_reg_lock(chip);
> err = mv88e6xxx_port_broadcast_sync(chip, port, broadcast);
> + mv88e6xxx_reg_unlock(chip);
> if (err)
> - goto out;
> + return err;
> }
>
> if (flags.mask & BR_PORT_LOCKED) {
> @@ -6599,10 +6605,8 @@ static int mv88e6xxx_port_bridge_flags(struct
> dsa_switch *ds, int port,
>
> err = mv88e6xxx_port_set_lock(chip, port, locked);
> if (err)
> - goto out;
> + return err;
> }
> -out:
> - mv88e6xxx_reg_unlock(chip);
>
> return err;
> }
> diff --git a/drivers/net/dsa/mv88e6xxx/port.c
> b/drivers/net/dsa/mv88e6xxx/port.c
> index 5e4d5e9265a4..2a60aded6fbe 100644
> --- a/drivers/net/dsa/mv88e6xxx/port.c
> +++ b/drivers/net/dsa/mv88e6xxx/port.c
> @@ -1222,15 +1222,19 @@ int mv88e6xxx_port_set_lock(struct
> mv88e6xxx_chip *chip, int port,
> u16 reg;
> int err;
>
> + mv88e6xxx_reg_lock(chip);
> err = mv88e6xxx_port_read(chip, port, MV88E6XXX_PORT_CTL0, &reg);
> - if (err)
> + if (err) {
> + mv88e6xxx_reg_unlock(chip);
> return err;
> + }
>
> reg &= ~MV88E6XXX_PORT_CTL0_SA_FILT_MASK;
> if (locked)
> reg |= MV88E6XXX_PORT_CTL0_SA_FILT_DROP_ON_LOCK;
>
> err = mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_CTL0, reg);
> + mv88e6xxx_reg_unlock(chip);
> if (err)
> return err;
>
> @@ -1247,7 +1251,11 @@ int mv88e6xxx_port_set_lock(struct
> mv88e6xxx_chip *chip, int port,
> MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT;
> }
>
> - return mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_ASSOC_VECTOR,
> reg);
> + mv88e6xxx_reg_lock(chip);
> + err = mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_ASSOC_VECTOR,
> reg);
> + mv88e6xxx_reg_unlock(chip);
> +
> + return err;
> }
>
> int mv88e6xxx_port_set_8021q_mode(struct mv88e6xxx_chip *chip, int
> port,
>
>> + if (err)
>> + return err;
>> + }
>>
>> - reg &= ~MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT;
>> - if (locked)
>> - reg |= MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT;
>> + reg = 0;
>> + if (locked) {
>> + reg = (1 << port);
>> + reg |= MV88E6XXX_PORT_ASSOC_VECTOR_IGNORE_WRONG |
>> + MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT;
>> + }
>>
>> return mv88e6xxx_port_write(chip, port, MV88E6XXX_PORT_ASSOC_VECTOR,
>> reg);
>> }
>> diff --git a/drivers/net/dsa/mv88e6xxx/port.h
>> b/drivers/net/dsa/mv88e6xxx/port.h
>> index e0a705d82019..5c1d485e7442 100644
>> --- a/drivers/net/dsa/mv88e6xxx/port.h
>> +++ b/drivers/net/dsa/mv88e6xxx/port.h
>> @@ -231,6 +231,7 @@
>> #define MV88E6XXX_PORT_ASSOC_VECTOR_LOCKED_PORT 0x2000
>> #define MV88E6XXX_PORT_ASSOC_VECTOR_IGNORE_WRONG 0x1000
>> #define MV88E6XXX_PORT_ASSOC_VECTOR_REFRESH_LOCKED 0x0800
>> +#define MV88E6XXX_PORT_ASSOC_VECTOR_PAV_MASK 0x07ff
>>
>> /* Offset 0x0C: Port ATU Control */
>> #define MV88E6XXX_PORT_ATU_CTL 0x0c
>> @@ -374,6 +375,7 @@ int mv88e6xxx_port_set_fid(struct mv88e6xxx_chip
>> *chip, int port, u16 fid);
>> int mv88e6xxx_port_get_pvid(struct mv88e6xxx_chip *chip, int port,
>> u16 *pvid);
>> int mv88e6xxx_port_set_pvid(struct mv88e6xxx_chip *chip, int port,
>> u16 pvid);
>>
>> +bool mv88e6xxx_port_is_locked(struct mv88e6xxx_chip *chip, int port);
>> int mv88e6xxx_port_set_lock(struct mv88e6xxx_chip *chip, int port,
>> bool locked);
>>