[PATCH] net: tftpboot: clear timeout_count on every successful block

[Mikhail Kshevetskiy]

On 04.12.2024 18:13, Simon Glass wrote:
> Hi Mikhail,
>
> On Tue, 3 Dec 2024 at 16:27, Mikhail Kshevetskiy
> <mikhail.kshevetskiy at iopsys.eu> wrote:
>> timeout_count is never reset once a tftpboot transfer has started. If for
>> whatever reason timeouts occur frequently, but the server keeps replying
>> nonetheless, the transfer may be needlessly aborted.
>>
>> Reset timer_count on every successful block to avoid this situation.
>>
>> Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy at iopsys.eu>
>> ---
>>  net/tftp.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
> What is the impact of this change?

If less than timeout_count_max issues appeared between arriving of two
data blocks -- the transfer will be continued. This greatly increase
chances to successfully download file if a lot of transfer timeout happens.

>From the other side the transfer may becomes very slow (if timeouts will be
after each packet).

This may looks unrealistic, but we have a number of devices with Airoha chips
(mips, mipsel, arm, aarch64) that sometimes acts like stated above (a timeout
arises very often, but some packets flows normally). It's a rare issue, but
sometimes happens :-( We don't know a reason yet.


>> diff --git a/net/tftp.c b/net/tftp.c
>> index 704b20b4ff8..8f948204a6f 100644
>> --- a/net/tftp.c
>> +++ b/net/tftp.c
>> @@ -498,6 +498,7 @@ static void tftp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
>>                                                 tftp_state = STATE_DATA;
>>                                                 tftp_remote_port = src;
>>                                         }
>> +                                       timeout_count = 0;
>>                                         tftp_send(); /* Send next data block */
>>                                 }
>>                         }
>> @@ -657,6 +658,7 @@ static void tftp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
>>                         net_set_state(NETLOOP_FAIL);
>>                         break;
>>                 }
>> +               timeout_count = 0;
>>
>>                 if (len < tftp_block_size) {
>>                         tftp_send();
>> --
>> 2.45.2
>>
> Regards,
> Simon