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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2018-11-20 12:40:25 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-11-27 20:31:54 -0500
commit7c6ea35ef50810aa12ab26f21cb858d980881576 (patch)
tree9fc799fd26232ec5a9018d33d965bb048947aab8 /kernel
parent552701dd0fa7c3d448142e87210590ba424694a0 (diff)
downloadlinux-7c6ea35ef50810aa12ab26f21cb858d980881576.tar.bz2
function_graph: Reverse the order of pushing the ret_stack and the callback
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: 03274a3ffb449 ("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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace_functions_graph.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 4f0d72ae6362..2561460d7baf 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -188,15 +188,17 @@ int function_graph_enter(unsigned long ret, unsigned long func,
trace.func = func;
trace.depth = ++current->curr_ret_depth;
- /* Only trace if the calling function expects to */
- if (!ftrace_graph_entry(&trace))
- goto out;
-
if (ftrace_push_return_trace(ret, func,
frame_pointer, retp))
goto out;
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace))
+ goto out_ret;
+
return 0;
+ out_ret:
+ current->curr_ret_stack--;
out:
current->curr_ret_depth--;
return -EBUSY;