The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 7c6ea35ef50810aa12ab26f21cb858d980881576 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
Date: Tue, 20 Nov 2018 12:40:25 -0500
Subject: [PATCH] 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@xxxxxxxxxx
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
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;
