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

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Message-ID: <1377213994.1620.95.camel@empanada>
Date:	Thu, 22 Aug 2013 18:26:34 -0500
From:	Tom Zanussi <tom.zanussi@...el.com>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	rostedt@...dmis.org, linux-kernel@...r.kernel.org,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH v4 00/11] tracing: trace event triggers

On Thu, 2013-08-22 at 14:48 -0500, Tom Zanussi wrote:
> 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...
> 

Looks like I spoke too soon - in the few hours between testing this
patchset and posting it, some new commits hit for-next.

for-next rebase coming up...

Tom

> Thanks for all your comments,
> 
> Tom
> 
> > Thank you,
> > 
> 


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