Re: [PATCH] i2c: qup: jump out of the loop in case of timeout

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 28-Jun-25 17:58, Yang Xiwen wrote:
> On 6/16/2025 12:01 AM, Yang Xiwen via B4 Relay wrote:
>> From: Yang Xiwen <forbidden405@outlook.com>
>>
>> Original logic only sets the return value but doesn't jump out of the
>> loop if the bus is kept active by a client. This is not expected. A
>> malicious or buggy i2c client can hang the kernel in this case and
>> should be avoided. This is observed during a long time test with a
>> PCA953x GPIO extender.
>>
>> Fix it by changing the logic to not only sets the return value, but also
>> jumps out of the loop and return to the caller with -ETIMEDOUT.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Yang Xiwen <forbidden405@outlook.com>
>> ---
>>   drivers/i2c/busses/i2c-qup.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
>> index 3a36d682ed57..5b053e51f4c9 100644
>> --- a/drivers/i2c/busses/i2c-qup.c
>> +++ b/drivers/i2c/busses/i2c-qup.c
>> @@ -452,8 +452,10 @@ static int qup_i2c_bus_active(struct qup_i2c_dev *qup, int len)
>>           if (!(status & I2C_STATUS_BUS_ACTIVE))
>>               break;
>>   -        if (time_after(jiffies, timeout))
>> +        if (time_after(jiffies, timeout)) {
>>               ret = -ETIMEDOUT;
>> +            break;
>> +        }
>>             usleep_range(len, len * 2);
>>       }
>>
>> ---
>> base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
>> change-id: 20250615-qca-i2c-d41bb61aa59e
>>
>> Best regards,
> 
> Ping for review. The original logic error is very clear. This patch is also very small and can be reviewed in a short time.
> 
> If it insists on waiting for the bit to clear, it should not return -ETIMEDOUT then.

'return -ETIMEDOUT' makes sense here, AFAICT

Konrad