Re: [PATCH v4 00/11] tracing: trace event triggers

[Tom Zanussi]

Hi Masami,

Just getting back to this after returning from vacation - I'll be
sending an update to this patchset addressing your comments shortly...

On Thu, 2013-08-08 at 11:02 +0900, Masami Hiramatsu wrote:
> Hi,
> 
> (2013/07/30 1:40), Tom Zanussi wrote:
> > Hi,
> > 
> > This is v4 of the trace event triggers patchset, addressing more
> > comments from Masami Hiramatsu (thanks for the review and comments).
> > 
> > One of Masami's comments was on event_trigger_regex_open's use of
> > inode->i_private and that the same problem was being worked on by Oleg
> > Nesterov in other places.  That still seems to be the case, but in
> > order to address that, this patchset is built on top of the current
> > linux-trace/for-next but also including v2 of Oleg Nesterov's tracing:
> > open/delete fixes (but with v3 of the 6/6 patch). 
> 
> Does this patchset supports multibuffer? It seems that setting a
> trigger in an event of an instance affects the default event, but not
> the instance's event.

You're right of course - I went through the trouble of fixing up the
event filters to better support multibuffer, but neglected the
triggers. :-(   But as you point out in a later comment, the fix is
simple and I've updated the patchset to do that..

> e.g.
> 
> # mkdir instances/hoge
> # echo 'enable_event:mce:mce_record' > instances/hoge/events/syscalls/sys_enter_symlink/trigger
> # cat instances/hoge/events/syscalls/sys_enter_symlink/enable
> 0*
> # cat instances/hoge/events/mce/mce_record/enable
> 0
> # cat events/mce/mce_record/enable
> 0*
> # ln -sf /dev/null /tmp
> # cat instances/hoge/events/mce/mce_record/enable
> 0
> # cat events/mce/mce_record/enable
> 1*
> 
> This looks odd, I expected enabling mce/mce_record under instances/hoge.
> 
> And, there is a bug of ftrace itself (not introduced by this series) I've found.
> After the above operation, we can delete the instance "hoge", but the soft-mode
> flag of mce_record is not cleared, even though there is no trigger referring
> the event.
> 
> # rmdir instances/hoge
> # cat events/mce/mce_record/enable
> 1*
> 
> This is because the ftrace actually failed to remove(disable) the event trigger
> associated with the instance when doing rmdir, but it just removed that interface.
> 
> > v4:
> >  - made some changes to the soft-disable for syscall patch, according
> >    to Masami's suggestions.  Actually, since there's now an array of
> >    ftrace_files for syscalls that can serve the same purpose, the
> >    enabled_enter/exit_syscalls bit arrays became redundant and were
> >    removed.
> >  - moved all the remaining common functions out of the
> >    traceon/traceoff patch and into the basic trigger framework patch
> >    and added comments to all the common functions.
> >  - extensively commented the event_trigger_ops and event_command ops.
> >  - made the register/unregister_command functions __init.  Since that
> >    code was originally inspired by similar ftrace code, a new patch
> >    was added to do the same thing for the register/unregister of the
> >    ftrace commands (patch 10/11).
> >  - fixed the event_trigger_regex_open i_private problem noted by
> >    Masami that's currently being addressed by Oleg Nesterov's fixes
> >    for this.  Note that that patchset also affects patch 8/11 (update
> >    filters for multi-buffer, since it touches event filters as well).
> >    Patch 11/11 depends on that patchset and also moves
> >    event_file_data() to trace.h.b
> 
> OK, but I think the last 2 patches should be merged to 2/11 as updates.
> 

I did merge the last patch into the new series, but left 10/11 separate
because it really is just a cleanup independent of the trigger code.

> And also, could you rebase your patches on trace/for-next branch?
> Since that branch includes most of the latest fixes, it is better to
> review with it.
> 

Sure, but since now everything in for-next is in rc6, I've rebased on
rc6...

Thanks for all your comments,

Tom

> Thank you,
> 


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