Re: [PATCH v8 40/43] dyndbg: add epilogue to dynamic_debug/control file

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] ddebug_proc_start() fails to return EPILOGUE_TOKEN when resuming sequence iteration at the epilogue index, which violates seq_file semantics and causes the epilogue to be silently omitted if a read boundary falls exactly before it.
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commit c254572f4a41eba87d7288c5cb6c6ef71571d0a3
Author: Jim Cromie <jim.cromie@gmail.com>

dyndbg: add epilogue to dynamic_debug/control file

This commit adds an epilogue to the control-file to allow display of
statistics without disturbing the header. It introduces an EPILOGUE_TOKEN
yielded at the end of seq_file iteration.

> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index b7ccf471b5efe..d098afe8d340f 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c

[ ... ]

>  static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
>  {
>  	struct ddebug_iter *iter = m->private;
>  	struct _ddebug *dp;
>  
> +	(*pos)++;
> +
> +	if (p == EPILOGUE_TOKEN)
> +		return NULL;
> +
>  	if (p == SEQ_START_TOKEN)
>  		dp = ddebug_iter_first(iter);
>  	else
>  		dp = ddebug_iter_next(iter);
> -	++*pos;
> -	return dp;
> +
> +	if (dp)
> +		return dp;
> +
> +	return EPILOGUE_TOKEN;

[Severity: Medium]
Since ddebug_proc_next() now yields EPILOGUE_TOKEN as an additional sequence
element, does ddebug_proc_start() also need to be updated to handle resuming
iteration at the epilogue index?

If a read boundary falls exactly before the epilogue (where pos equals the
total number of items plus one), ddebug_proc_start() will iterate until dp
is NULL, and then return NULL instead of EPILOGUE_TOKEN:

lib/dynamic_debug.c:ddebug_proc_start() {
	...
	dp = ddebug_iter_first(iter);
	while (dp != NULL && --n > 0)
		dp = ddebug_iter_next(iter);
	return dp;
}

Will this cause the epilogue to be silently omitted in that scenario?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260905-dd-cmap-part2-clean-v8-0-a4cc0674f6fd@gmail.com?part=40