Wed, Mar 20, 2024 at 02:48:55PM CET, [email protected] wrote:
>mv88e6xxx supports multiple mdio buses as children, e.g. to model both
>internal and external phys. If the child buses mdio ids are truncated,
>they might collide which each other leading to an obscure error from
>kobject_add.
>
>The maximum length of bus id is currently defined as 61
>(MII_BUS_ID_SIZE). Truncation can occur on platforms with long node
>names and multiple levels before the parent bus on whiich the dsa switch
s/whiich/which/
>sits such as on CN9130 [1].
>
>Test whether the return value of snprintf exceeds the maximum bus id
>length and print a warning.
>
>[1]
>[ 8.324631] mv88e6085 f212a200.mdio-mii:04: switch 0x1760 detected: Marvell 88E6176, revision 1
>[ 8.389516] mv88e6085 f212a200.mdio-mii:04: Truncated bus-id may collide.
>[ 8.592367] mv88e6085 f212a200.mdio-mii:04: Truncated bus-id may collide.
>[ 8.623593] sysfs: cannot create duplicate filename '/devices/platform/cp0/cp0:config-space@f2000000/f212a200.mdio/mdio_bus/f212a200.mdio-mii/f212a200.mdio-mii:04/mdio_bus/!cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi'
>[ 8.785480] kobject: kobject_add_internal failed for !cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi with -EEXIST, don't try to register things with the same name in the same directory.
>[ 8.936514] libphy: mii_bus /cp0/config-space@f2000000/mdio@12a200/ethernet-switch@4/mdi failed to register
>[ 8.946300] mdio_bus !cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi: __mdiobus_register: -22
>[ 8.956003] mv88e6085 f212a200.mdio-mii:04: Cannot register MDIO bus (-22)
>[ 8.965329] mv88e6085: probe of f212a200.mdio-mii:04 failed with error -22
>
>Signed-off-by: Josua Mayer <[email protected]>
This is not bug fix, assume you target net-next. Please:
1) Next time, indicate that in the patch subject like this:
[patch net-next] xxx
2) net-next is currently closed, repost next week.
>---
> drivers/net/dsa/mv88e6xxx/chip.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
>index 614cabb5c1b0..1c40f7631ab1 100644
>--- a/drivers/net/dsa/mv88e6xxx/chip.c
>+++ b/drivers/net/dsa/mv88e6xxx/chip.c
>@@ -3731,10 +3731,12 @@ static int mv88e6xxx_mdio_register(struct mv88e6xxx_chip *chip,
>
> if (np) {
> bus->name = np->full_name;
>- snprintf(bus->id, MII_BUS_ID_SIZE, "%pOF", np);
>+ if (snprintf(bus->id, MII_BUS_ID_SIZE, "%pOF", np) >= MII_BUS_ID_SIZE)
>+ dev_warn(chip->dev, "Truncated bus-id may collide.\n");
How about instead of warn&fail fallback to some different name in this
case?
> } else {
> bus->name = "mv88e6xxx SMI";
>- snprintf(bus->id, MII_BUS_ID_SIZE, "mv88e6xxx-%d", index++);
>+ if (snprintf(bus->id, MII_BUS_ID_SIZE, "mv88e6xxx-%d", index++) >= MII_BUS_ID_SIZE)
How exactly this may happen?
>+ dev_warn(chip->dev, "Truncated bus-id may collide.\n");
> }
>
> bus->read = mv88e6xxx_mdio_read;
>
>---
>base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
>change-id: 20240320-mv88e6xxx-truncate-busid-34a1d2769bbf
>
>Sincerely,
>--
>Josua Mayer <[email protected]>
>
>
Am 20.03.24 um 15:09 schrieb Jiri Pirko:
> Wed, Mar 20, 2024 at 02:48:55PM CET, [email protected] wrote:
>> mv88e6xxx supports multiple mdio buses as children, e.g. to model both
>> internal and external phys. If the child buses mdio ids are truncated,
>> they might collide which each other leading to an obscure error from
>> kobject_add.
>>
>> The maximum length of bus id is currently defined as 61
>> (MII_BUS_ID_SIZE). Truncation can occur on platforms with long node
>> names and multiple levels before the parent bus on whiich the dsa switch
> s/whiich/which/
>
>
>> sits such as on CN9130 [1].
>>
>> Test whether the return value of snprintf exceeds the maximum bus id
>> length and print a warning.
>>
>> [1]
>> [ 8.324631] mv88e6085 f212a200.mdio-mii:04: switch 0x1760 detected: Marvell 88E6176, revision 1
>> [ 8.389516] mv88e6085 f212a200.mdio-mii:04: Truncated bus-id may collide.
>> [ 8.592367] mv88e6085 f212a200.mdio-mii:04: Truncated bus-id may collide.
>> [ 8.623593] sysfs: cannot create duplicate filename '/devices/platform/cp0/cp0:config-space@f2000000/f212a200.mdio/mdio_bus/f212a200.mdio-mii/f212a200.mdio-mii:04/mdio_bus/!cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi'
>> [ 8.785480] kobject: kobject_add_internal failed for !cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi with -EEXIST, don't try to register things with the same name in the same directory.
>> [ 8.936514] libphy: mii_bus /cp0/config-space@f2000000/mdio@12a200/ethernet-switch@4/mdi failed to register
>> [ 8.946300] mdio_bus !cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi: __mdiobus_register: -22
>> [ 8.956003] mv88e6085 f212a200.mdio-mii:04: Cannot register MDIO bus (-22)
>> [ 8.965329] mv88e6085: probe of f212a200.mdio-mii:04 failed with error -22
>>
>> Signed-off-by: Josua Mayer <[email protected]>
> This is not bug fix, assume you target net-next. Please:
> 1) Next time, indicate that in the patch subject like this:
> [patch net-next] xxx
> 2) net-next is currently closed, repost next week.
Correct, thanks - will do.
Just for future reference for those occasional contributors -
is there such a thing as an lkml calendar?
>
>> ---
>> drivers/net/dsa/mv88e6xxx/chip.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
>> index 614cabb5c1b0..1c40f7631ab1 100644
>> --- a/drivers/net/dsa/mv88e6xxx/chip.c
>> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
>> @@ -3731,10 +3731,12 @@ static int mv88e6xxx_mdio_register(struct mv88e6xxx_chip *chip,
>>
>> if (np) {
>> bus->name = np->full_name;
>> - snprintf(bus->id, MII_BUS_ID_SIZE, "%pOF", np);
>> + if (snprintf(bus->id, MII_BUS_ID_SIZE, "%pOF", np) >= MII_BUS_ID_SIZE)
>> + dev_warn(chip->dev, "Truncated bus-id may collide.\n");
> How about instead of warn&fail fallback to some different name in this
> case?
Duplicate could be avoided by truncating from the start,
however I don't know if that is a good idea.
It affects naming of paths in sysfs, and the root cause is
difficult to spot.
>> } else {
>> bus->name = "mv88e6xxx SMI";
>> - snprintf(bus->id, MII_BUS_ID_SIZE, "mv88e6xxx-%d", index++);
>> + if (snprintf(bus->id, MII_BUS_ID_SIZE, "mv88e6xxx-%d", index++) >= MII_BUS_ID_SIZE)
> How exactly this may happen?
It can happen on switch nodes at deep levels in the device-tree,
while describing both internal and external mdio buses of a switch.
E.g. Documentation/devicetree/bindings/net/dsa/marvell,mv88e6xxx.yaml
On CN9130 platform device-tree looks like this:
/ {
cp0 {
config-space@f2000000 {
mdio@12a200 {
ethernet-switch@4 {
mdio { ... };
mdio-external { ... };
};
};
};
};
};
For mdio-external child all the names alone, without separators,
make up 66 characters, exceeding: MII_BUS_ID_SIZE:
cp0config-space@f2000000mdio@12a200ethernet-switch@4mdio-external
With separators ('!') we have:
cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdio
cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdio-external
Truncated to MII_BUS_ID_SIZE:
cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi
cp0!config-space@f2000000!mdio@12a200!ethernet-switch@4!mdi
They become duplicates.
>> + dev_warn(chip->dev, "Truncated bus-id may collide.\n");
Another option (imo) is to force the issue and return error code.
Then the only way out would be increase of MII_BUS_ID_SIZE.
>> }
>>
>> bus->read = mv88e6xxx_mdio_read;
>>
>> ---
>> base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
>> change-id: 20240320-mv88e6xxx-truncate-busid-34a1d2769bbf
>>
>> Sincerely,
>> --
>> Josua Mayer <[email protected]>
>>
>>