Re: [PATCH] pahole: do not return an error when printing only a specific class

["Alexis Lothoré" <alexis.lothore@bootlin.com>]

Hi Ihor,

On Wed Jul 23, 2025 at 1:42 AM CEST, Ihor Solodrai wrote:
> On 7/16/25 2:04 AM, Alexis Lothoré (eBPF Foundation) wrote:

[...]

>>   	cu__finalize(cu, cus, conf);
>> -	if (cus__steal_now(cus, cu, conf) == LSK__STOP_LOADING)
>> +	if (cus__steal_now(cus, cu, conf) == LSK__ABORT)
>>   		goto out_abort;
>
> I think we should handle both LSK__STOP_LOADING and LSK__ABORT here,
> otherwise the worker will keep loading DWARF (which is most of the
> pahole's work) and passing cu-s to the stealer function.
>
> I guess in many cases it'll complete without errors, but it's just
> unnecessary work.
>
> Maybe add a check for LSK__STOP_LOADING here with goto_ok?

Hmmm, I am not sure how to follow you here. Even if cus__steal_now returns
LSK__STOP_LOADING, I need to return DWARF_CB_OK from
cus__merge_and_process_cu, otherwise it will be processed as an error
again. Or are you suggesting just make sure to delete current cu but still
return DWARF_CB_OK when getting LSK__STOP_LOADING, as done below ?

--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -3796,6 +3796,7 @@ static int cus__merge_and_process_cu(struct cus *cus, struct conf_load *conf,
        Dwarf_Off off = 0, noff;
        struct cu *cu = NULL;
        size_t cuhl;
+       int res;

        while (dwarf_nextcu(dw, off, &noff, &cuhl, NULL, &pointer_size,
                            &offset_size) == 0) {
@@ -3874,7 +3875,8 @@ static int cus__merge_and_process_cu(struct cus *cus, struct conf_load *conf,
                goto out_abort;

        cu__finalize(cu, cus, conf);
-       if (cus__steal_now(cus, cu, conf) == LSK__ABORT)
+       res = cus__steal_now(cus, cu, conf);
+       if (res == LSK__STOP_LOADING || res == LSK__ABORT)
                goto out_abort;

        return 0;
@@ -3882,7 +3884,7 @@ static int cus__merge_and_process_cu(struct cus *cus, struct conf_load *conf,
 out_abort:
        dwarf_cu__delete(cu);
        cu__delete(cu);
-       return DWARF_CB_ABORT;
+       return res == LSK__STOP_LOADING ? DWARF_CB_OK : DWARF_CB_ABORT;
 }


Thanks,

Alexis


-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com