tracing/fgraph: Fix set_graph_function from showing interrupts
The tracefs file set_graph_function is used to only function graph functions that are listed in that file (or all functions if the file is empty). The way this is implemented is that the function graph tracer looks at every function, and if the current depth is zero and the function matches something in the file then it will trace that function. When other functions are called, the depth will be greater than zero (because the original function will be at depth zero), and all functions will be traced where the depth is greater than zero. The issue is that when a function is first entered, and the handler that checks this logic is called, the depth is set to zero. If an interrupt comes in and a function in the interrupt handler is traced, its depth will be greater than zero and it will automatically be traced, even if the original function was not. But because the logic only looks at depth it may trace interrupts when it should not be. The recent design change of the function graph tracer to fix other bugs caused the depth to be zero while the function graph callback handler is being called for a longer time, widening the race of this happening. This bug was actually there for a longer time, but because the race window was so small it seldom happened. The Fixes tag below is for the commit that widen the race window, because that commit belongs to a series that will also help fix the original bug. Cc: stable@kernel.org Fixes: 39eb456d ("function_graph: Use new curr_ret_depth to manage depth instead of curr_ret_stack") Reported-by:Joe Lawrence <joe.lawrence@redhat.com> Tested-by:
Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by:
Steven Rostedt (VMware) <rostedt@goodmis.org>
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0c7a52e4
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