Messages in this thread | | | Date | Wed, 20 Mar 2024 08:13:35 -0700 | Subject | Re: [PATCH] net: dsa: mv88e6xxx: add warning for truncated mdio bus id | From | Florian Fainelli <> |
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On 3/20/2024 7:33 AM, Josua Mayer wrote: > Am 20.03.24 um 15:09 schrieb Jiri Pirko: >> Wed, Mar 20, 2024 at 02:48:55PM CET, josua@solid-run.com 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 <josua@solid-run.com> >> 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?
There is this: https://patchwork.hopto.org/net-next.html
>> >>> --- >>> 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
We should consider moving these types of checks into the MDIO bus core, or at least introduce a helper function such that it embeds the check in it. -- Florian
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