On 07/19, Masami Hiramatsu wrote: > > (2013/07/18 23:51), Oleg Nesterov wrote: > > It removes trace_array_get/put from tracing_open_generic_file() and > > tracing_release_generic_file(). This assumes that "call->flags++" is > > enough, but it is not. > > No, it replaces trace_array_get/put with ftrace_event_file_get/put > which calls trace_array_get/put inside.
Ah, I didn't notice your patch adds "file->tr->ref++" into ftrace_event_file_get... So I was wrong in any case, thanks for correcting me. But, > (Just one point, previous ftrace_event_file_get has a racy point > when it does tr->ref++, it should be fixed.) Not sure what do you mean, but unless I missed something again this "tr->ref++" above still looks racy. instance_delete() checks tr->ref first, then it takes event_mutex and removes/kfrees event_files. But this doesn't really matter even if I am right, surely this can be fixed. My only point, imho this is more complex than necessary. In particular, > > IOW, I believe that either .open() should do trace_array_get(), or > > __trace_remove_event_dirs() needs another for-each-file loop which > > checks file->call->flags & TRACE_EVENT_FL_REF_MASK. > > Agreed :) Yes ;) and this makes the ref-counting even more complex, we use different methods to avoid the races with rmdir and event_remove(). > > The same bugs which Steven's 1/4 tries to solve ;) > > OK, let me confirm that, would you mean we still need 2/4 - 4/4? Yes, yes. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
