On 2023/06/02 13:49, lijiang wrote:
> On Fri, Jun 2, 2023 at 10:18 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@nec.com>
> wrote:
>
>> On 2023/05/30 21:30, lijiang wrote:
>>> On Mon, May 29, 2023 at 9:03 AM HAGIO KAZUHITO(萩尾 一仁) <
>> k-hagio-ab@nec.com>
>>> wrote:
>>>
>>>>>
>>>>> +                                       for (j = MOD_TEXT; j <
>>>>>> MOD_MEM_NUM_TYPES; j++) {
>>>>>> +                                               lm->load_symtable[j] =
>>>>>> NULL;
>>>>>> +                                               lm->load_symend[j] =
>>>> NULL;
>>>>>> +                                       }
>>>>>> +                               } else { /* somehow this function runs
>>>> for
>>>>>> unloaded modules */
>>>>>>
>>>>>
>>>>> Could you please explain why it may get into the "else" code path? And
>>>> why
>>>>> do we need to handle this situation for now? But not needed before the
>>>>> module memory changes.
>>>>
>>>> This path is used by "mod -d|-D" and reinit_modules() for unloaded
>> modules.
>>>>
>>>> The old procedure always does the cleanup and reinstall of the hash
>>>> entries, so kept it as it is.
>>>>
>>>
>>> I tried to add some debug information in the above code path, but did not
>>> observe any output(via the mod -d/-D). It's strange.
>>
>> With this change,
>>
>> --- a/symbols.c
>> +++ b/symbols.c
>> @@ -13951,6 +13951,7 @@ delete_load_module(ulong base_addr)
>>                                                   lm->load_symend[j] = NULL;
>>                                           }
>>                                   } else { /* somehow this function runs
>> for unloaded modules */
>> +                                       fprintf(fp, "in the else block
>> (-D)\n");
>>                                           for (j = MOD_TEXT; j <
>> MOD_MEM_NUM_TYPES; j++) {
>>                                                   if (!lm->symtable[j])
>>                                                           continue;
>> @@ -14016,6 +14017,7 @@ delete_load_module(ulong base_addr)
>>                                                   lm->load_symend[j] = NULL;
>>                                           }
>>                                   } else { /* somehow this function runs
>> for unloaded modules */
>> +                                       fprintf(fp, "in the else block
>> (-d)\n");
>>                                           for (j = MOD_TEXT; j <
>> MOD_MEM_NUM_TYPES; j++) {
>>                                                   if (!lm->symtable[j])
>>                                                           continue;
>>
>> These should be printed:
>>
>> crash-6.4> mod -s dm_mod
>>        MODULE       NAME                     TEXT_BASE         SIZE  OBJECT
>> FILE
>> ffffffffc042fd00  dm_mod                ffffffffc0418000   237568
>> dm-mod.ko
>> crash-6.4> mod -d dm_mod
>> crash-6.4> mod -d dm_mod
>>
>
> Ah, I know why I did not see any output(via the mod -d/-D), because I only
> ran the "mod -d/-D" *once*. And for now I can see the debug information
> after running the mod -d/-D *twice*.

ok, good.

but I tested it without the clean-up and re-install, it looked ok.
So I'm thinking to remove them.

Thanks,
Kazu

>
> Thank you for the explanation, Kazu.
>
>
>> in the else block (-d)
>> crash-6.4> mod -d dm_log
>> in the else block (-d)
>> crash-6.4> mod -D | head
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>> in the else block (-D)
>>
>> Thanks,
>> Kazu
>>