On Tue, Feb 04, 2014 at 02:13:15PM -0500, Steven Rostedt wrote: > When debug preempt is enabled, preempt_disable() can be traced by > function and function graph tracing. > > There's a place in the function graph tracer that calls trace_clock() > which eventually calls cycles_2_ns() outside of the recursion > protection. When cycles_2_ns() calls preempt_disable() it gets traced > and the graph tracer will go into a recursive loop causing a crash or > worse, a triple fault. > > Simple fix is to use preempt_disable_notrace() in cycles_2_ns, which > makes sense because the preempt_disable() tracing may use that code > too, and it tracing it, even with recursion protection is rather > pointless. > > Signed-off-by: Steven Rostedt <[email protected]>
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