On Tue, 2013-07-16 at 18:38 +0200, Oleg Nesterov wrote: > On 07/15, Oleg Nesterov wrote: > > > > So. As Masami pointed out, this is not enough. Probably we can add more > > hacks, but I'd like to discuss the alternative approach. > > > > Note also that this ref count has the unfortunate property, if someone > > keeps the file opened we can't remove an event. > > And please correct me, but afaics there are similar problems with > rmdir instances/xxx.
The instances have their own refcount. And if a file is open, it wont remove the directory. Just try it... # cd /sys/kernel/debug/tracing/instances # mkdir foo # sleep 10 < foo/events/ext3/enable & [1] 2087 # rmdir foo rmdir: failed to remove `foo': Device or resource busy # [1]+ Done sleep 10 < foo/events/ext3/enable # rmdir foo # > > > What this patch does: > > > > - add the new "topmost" rw_semaphore, file_sem. > > probably unneeded... > > > - trace_remove_event_call() takes this sem for writing and > > cleares enable/id/format/filter->i_private > > > > - removes tracing_open_generic_file/tracing_release_generic_file, > > we do not use file->f_private any longer > > > > - changes event_enable_read/event_enable_write to read > > ftrace_event_file = i_private under read_lock(file_sem) and > > abort if it is null. > > > > Question: why event_enable_write() needs trace_array_get() ? > > probably it doesn't... I'm confused. Which code has event_enable_write doing a trace_array_get()? > > > Steven, Masami, do you think this can make any sense? I need to sort these patches out. They are all over the place. What exactly do we have for a solution here. Did we figure out which patches are needed? I'll have to go back and re-read the entire thread. I've been all over the place lately with different topics, and don't remember all that has been said here. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
