On Tue, 3 Nov 2015, Josh Poimboeuf wrote: > On Tue, Nov 03, 2015 at 05:09:48PM +0100, Miroslav Benes wrote: > > On Tue, 3 Nov 2015, Josh Poimboeuf wrote: > > > > > On Tue, Nov 03, 2015 at 11:52:08AM +0100, Miroslav Benes wrote: > > > > > > > > There is a problem which I missed before. klp_init_func() is called before > > > > klp_find_verify_func_addr() in klp_init_object(). This means that > > > > func->old_addr is either not verified yet or worse it is still 0. This > > > > means that klp_get_func_pos_callback() never returns 1 and is thus called > > > > on each symbol. So if you for example patched cmdline_proc_show the > > > > resulting directory in sysfs would be called cmdline_proc_show,1 because > > > > addr is never matched. Had old_addr been specified the name would have > > > > been probably correct, but not for sure. > > > > > > > > This should be fixed as well. > > > > > > Even worse, klp_init_func() can be called even if the object hasn't been > > > loaded. In that case there's no way to know what the value of n is, and > > > therefore no way to reliably create the sysfs entry. > > > > Ah, right. > > > > > Should we create "func,n" in klp_init_object_loaded() instead of > > > klp_init_func()? > > > > So that the function entries in sysfs would be created only when the > > object is loaded? Well, why not, but in that case it could easily confuse > > the user. > > Maybe, but I think it would be fine if we document it. It should only > be relied on by tools, anyway. Agreed. > > Object entry would be empty for not loaded object. I would not > > dare to propose to remove such object entries. It would make things worse. > > Why would removing an empty object entry make things worse? I think it all comes down to a question whether the sysfs entries say what a patch is capable to patch or what this patch is currently patching in the system. I am inclined to the former so the removal would make me nervous. But I am not against the second approach. We are still in testing mode as far as sysfs is concerned so we can try even harsh changes and see how it's gonna go. > > So maybe we could introduce an attribute in sysfs object entry which would > > say if the object is loaded or not. Or something like that. > > Hm, I'm not sure I see how this would help. Hopefully I cleared this up with the above. Miroslav -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
