Steven Rostedt (VMware) a22ff9df71 function_graph: Reverse the order of pushing the ret_stack and the callback ...

commit 7c6ea35ef5 upstream.

The function graph profiler uses the ret_stack to store the "subtime" and
reuse it by nested functions and also on the return. But the current logic
has the profiler callback called before the ret_stack is updated, and it is
just modifying the ret_stack that will later be allocated (it's just lucky
that the "subtime" is not touched when it is allocated).

This could also cause a crash if we are at the end of the ret_stack when
this happens.

By reversing the order of the allocating the ret_stack and then calling the
callbacks attached to a function being traced, the ret_stack entry is no
longer used before it is allocated.

Cc: stable@kernel.org
Fixes: 03274a3ffb ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2018-12-05 19:32:11 +01:00

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