Messages in this thread | | | Date | Tue, 21 Aug 2012 19:10:17 -0700 | From | Anton Vorontsov <> | Subject | Re: [PATCH v3] pstore/ftrace: Convert to its own enable/disable debugfs knob |
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On Tue, Aug 21, 2012 at 09:07:19PM -0400, Steven Rostedt wrote: [...] > I'm fine with it. I know there was some issues about recursion > protection and I said that the function tracer now has its own > protection where you don't need to worry about it. I was hoping that > code would make it into 3.6, but Linus opened the merge window the day > after I posted the final version. Which I figured was too close to the > merge window to push for 3.6 (lots of changes occurred, and I wanted > it vetted in linux-next for a bit). > > Now those changes are queued for 3.7 and are currently in the tip > tree. You can supply your own temporary recursion protection to the > function tracer callback, or wait till my changes make it into Linus's > tree.
Great! Btw, the particular recursion issue that I faced back then was triggered by a missing 'notrace' specifier for the ->write() callback in pstore code, i.e. a bug in pstore.
Running without any recursion protection is prone to weird lockups/reboots, and probably a good idea to have it on a production system. But recursion during tracing is still an evidence of some other bugs, right? At least the fact that I didn't have it helped me to find a bug. So, does it make sense to make the recursion protection optionally disabled? Maybe as some CONFIG_DEBUG_* option (briefly looking into kernel/trace/Kconfig I didn't find any)?
Thanks,
Anton.
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