Messages in this thread | | | Subject | Re: [PATCH 19/19] [INCOMPLETE] ARM: make return_address available for ARM_UNWIND | From | Steven Rostedt <> | Date | Fri, 25 Jan 2013 11:44:14 -0500 |
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[ I got an error with linux-arm-kernel@list.infradead.org and had to remove from CC ]
On Fri, 2013-01-25 at 16:26 +0000, Dave Martin wrote:
> However, if the purpose if making return_address() notrace is just to > prevent infinite recursion, where finite recursion is safe, then it > feels fixable as described above. > > Steven, do you know whether such an approach might be safe? >
I rewrote the function trace recursion code (see linux-next). The function tracer wont recurse on itself. If the return_address() is only used by callbacks and not directly by the mcount(ftrace_caller), then after the first trace, ftrace wont let recursion of the callback. IOW, callbacks of ftrace don't need to worry about re-entrancy at the same context level (but do for different contexts, ie. normal, irq, softirq and NMI).
(commit edc15cafcbfa3d73f819cae99885a2e35e4cbce5 in linux-next and friends)
-- Steve
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