On Fri, Jun 2, 2023 at 10:18 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> 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@xxxxxxx>
> 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*.
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
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