On 2022/11/14 18:31, Jiri Olsa wrote: > On Mon, Nov 14, 2022 at 06:00:38PM +0800, Leizhen (ThunderTown) wrote: >> >> >> On 2022/11/14 17:27, Jiri Olsa wrote: >>> On Mon, Nov 14, 2022 at 04:50:25PM +0800, Leizhen (ThunderTown) wrote: >>>> >>>> On 2022/11/14 15:47, Jiri Olsa wrote: >>>>> On Wed, Nov 02, 2022 at 04:49:19PM +0800, Zhen Lei wrote: >>>>>> Currently we traverse all symbols of all modules to find the specified >>>>>> function for the specified module. But in reality, we just need to find >>>>>> the given module and then traverse all the symbols in it. >>>>> hi, >>>>> sorry for delayed answer, I did not notice this until Stephen's email >>>>> about merge issue with recent bpf change [1] >>>>> >>>>>> Let's add a new parameter 'const char *modname' to function >>>>>> module_kallsyms_on_each_symbol(), then we can compare the module names >>>>> we have use case for iterating all modules and their symbols when we >>>>> want to resolve passed addresses for tracing >>>>> >>>>> we don't have 'modname' that we could pass, we need to iterate all modules >>>>> >>>>> so perhaps this could be made optional like with passing NULL for modname? >>>> The deletion of modname was suggested by Petr Mladek. The reason is that >>>> everyone passes modname as NULL, there was no actual demand at the time. >>>> https://lkml.org/lkml/2022/9/20/682 >>>> >>>>>> directly in this function and call hook 'fn' after matching. And the >>>>>> parameter 'struct module *' in the hook 'fn' can also be deleted. >>>>> we need 'struct module *' argument in the callback as well because we are >>>>> taking the module reference if we trace function in it, so it wont get >>>>> unloaded >>>>> >>>>> please let me know if I should do the change or can help in any way >>>> It seems that we should take the module reference before invoking callback >>>> and put it after it is called, without passing modname. >>> we take the module ref only if we (callback) find the traced address in >>> the module, we don't have the module object before >>> >>> jirka >>> >> >> Do it in function module_kallsyms_on_each_symbol()? >> >> But I just saw that mutex_lock(&module_mutex) protection is already >> provided in this function. So reference counting protection may not >> be required. > > we take the module ref so it won't unload even outside of the > module_kallsyms_on_each_symbol function There's another way to do it, but it's more time consuming. struct module *__module_text_address(unsigned long addr); struct module *__module_address(unsigned long addr); Which way do you think is more appropriate? > > jirka > . > -- Regards, Zhen Lei
