Re: [PATCH 2/2] tracing/events/lockdep: move tracepoints withinrecursive protection

From: Peter Zijlstra
Date: Thu Apr 16 2009 - 12:48:21 EST


On Thu, 2009-04-16 at 12:15 -0400, Steven Rostedt wrote:
> plain text document attachment
> (0002-tracing-events-lockdep-move-tracepoints-within-recu.patch)
> From: Steven Rostedt <srostedt@xxxxxxxxxx>
>
> With the current location of the tracepoints in lockdep, the system
> can hard lockup in minutes when the tracepoints are enabled.
>
> Moving the tracepoints outside inside the lockdep protection solves
> the issue.

NAK

the idea is to eventually move lockdep on top of the tracepoints. The
tracer should grow to be more robust and handle recursion itself.

Its likely a case of the tracer using a spinlock or mutex in the
tracepoint code. When I did the tracepoints I converted one such to a
raw_spinlock_t in the trace_print code.



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