Re: [PATCH] net: usb: lan78xx: Fix lost EEPROM write timeout error(-ETIMEDOUT) in lan78xx_write_raw_eeprom

Paolo Abeni
2025-10-09T08:02:49Z

Hello,

On 10/9/25 7:41 AM, Bhanu Seshu Kumar Valluri wrote:
> On 09/10/25 11:00, Bhanu Seshu Kumar Valluri wrote:
>> The function lan78xx_write_raw_eeprom failed to properly propagate EEPROM
>> write timeout errors (-ETIMEDOUT). In the timeout fallthrough path, it first
>> attempted to restore the pin configuration for LED outputs and then
>> returned only the status of that restore operation, discarding the
>> original timeout error saved in ret.
>>
>> As a result, callers could mistakenly treat EEPROM write operation as
>> successful even though the EEPROM write had actually timed out with no
>> or partial data write.
>>
>> To fix this, handle errors in restoring the LED pin configuration separately.
>> If the restore succeeds, return any prior EEPROM write timeout error saved
>> in ret to the caller.
>>
>> Suggested-by: Oleksij Rempel <o.rempel@pengutronix.de>
>> Fixes: 8b1b2ca83b20 ("net: usb: lan78xx: Improve error handling in EEPROM and OTP operations")
>> cc: stable@vger.kernel.org
>> Signed-off-by: Bhanu Seshu Kumar Valluri <bhanuseshukumar@gmail.com>
>> ---
>> Note:
>> The patch is compiled and tested using EVB-LAN7800LC.
>> The patch was suggested by Oleksij Rempel while reviewing a fix to a bug
>> found by syzbot earlier.
>> The review mail chain where this fix was suggested is given below.
>> https://lore.kernel.org/all/aNzojoXK-m1Tn6Lc@pengutronix.de/
>>
>> ChangeLog:
>> v1->v2:
>> Added cc:stable tag as asked during v1 review.
>> V1 Link : https://lore.kernel.org/all/20251004040722.82882-1-bhanuseshukumar@gmail.com/
>>
>> drivers/net/usb/lan78xx.c | 11 +++++++----
>> 1 file changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
>> index d75502ebbc0d..5ccbe6ae2ebe 100644
>> --- a/drivers/net/usb/lan78xx.c
>> +++ b/drivers/net/usb/lan78xx.c
>> @@ -1174,10 +1174,13 @@ static int lan78xx_write_raw_eeprom(struct lan78xx_net *dev, u32 offset,
>> }
>>
>> write_raw_eeprom_done:
>> - if (dev->chipid == ID_REV_CHIP_ID_7800_)
>> - return lan78xx_write_reg(dev, HW_CFG, saved);
>> -
>> - return 0;
>> + if (dev->chipid == ID_REV_CHIP_ID_7800_) {
>> + int rc = lan78xx_write_reg(dev, HW_CFG, saved);
>> + /* If USB fails, there is nothing to do */
>> + if (rc < 0)
>> + return rc;
>> + }
>> + return ret;
>> }
>>
>> static int lan78xx_read_raw_otp(struct lan78xx_net *dev, u32 offset,
>
> Hi,
>
> The subject prefix must be [PATCH v2] instead. I overlooked it. Should I resend it?

This is not a review, and given the current amount of queued patches a
real one will not follow soon, but please do not send a new version just
for this.

Thanks,

Paolo