Messages in this thread |  | | | Date | Sat, 11 Apr 2009 16:48:33 +0200 | | From | Frederic Weisbecker <> | | Subject | Re: [PATCH 0/7] tracing: bug fixes for tracing/filters |
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On Sat, Apr 11, 2009 at 04:30:48AM -0500, Tom Zanussi wrote: > Hi, > > On Sat, 2009-04-11 at 15:52 +0800, Li Zefan wrote: > > This patchset fixes some bugs in tracing/filters. Most of the change > > goes to the last patch, and others are small ones. > > > > At first glance, they look good and fix real problems - thanks for > fixing them. Re patch 7, there's been some discussion about using rcu > for this. See: > > http://lkml.org/lkml/2009/4/5/46 > > >From that discussion, it seems some non-trivial changes to rcu would be > needed for this. I'm playing around with a different idea now to > hopefully avoid the need for that, or the other approach mentioned, of > temporarily stopping tracing while removing/changing the filters. > > Basically my thought is to avoid the problem by not allocating or > destroying the preds when removing filters but instead switch out the > pred->fns with a nop version while keeping the fields intact for awhile. > I think that will work for removing filters, but I still need to think > about how it would (or would not) work for replacing them. > > Tom
It would be sort of reinventing rcu :-) Well, Paul proposed something recently, hmm I should double check this discussion.
Anyway, the fixes from Li (other than 4 and 7 for which we have comments) look very good!
Frederic.
> > > Maybe 3rd to 6th patches can be regarded as small enhancements instead > > of bug fixes? But they are behavioural changes. > > > > > > [PATCH 1/7] tracing/filters: NUL-terminate user input filter > > [PATCH 2/7] tracing/filters: fix NULL pointer dereference > > [PATCH 3/7] tracing/filters: allow user input integer to be oct or hex > > [PATCH 4/7] tracing/filters: allow user to specify a filter val to be string > > [PATCH 5/7] tracing/filters: disallow newline as delimeter > > [PATCH 6/7] tracing/filters: return proper error code when writing filter file > > [PATCH 7/7] tracing/filters: make filter preds RCU safe > > > > kernel/trace/trace.h | 6 +- > > kernel/trace/trace_events.c | 16 +++-- > > kernel/trace/trace_events_filter.c | 131 ++++++++++++++++++++++++++--------- > > kernel/trace/trace_events_stage_3.h | 10 +++- > > 4 files changed, 121 insertions(+), 42 deletions(-) > > --- >
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