[PATCH 4/9] tracing: Add proper check for irq_depth routines

[Steven Rostedt]

From: Jiri Olsa <jolsa@xxxxxxxxxx>

The check_irq_entry and check_irq_return could be called
from graph event context. In such case there's no graph
private data allocated. Adding checks to handle this case.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
LKML-Reference: <20100924154102.GB1818@xxxxxxxxxxxxxxxxxxxx>

[ Fixed some grammar in the comments ]

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace_functions_graph.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 02c708a..47a8b8b 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -887,12 +887,20 @@ check_irq_entry(struct trace_iterator *iter, u32 flags,
 		unsigned long addr, int depth)
 {
 	int cpu = iter->cpu;
+	int *depth_irq;
 	struct fgraph_data *data = iter->private;
-	int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
 
-	if (flags & TRACE_GRAPH_PRINT_IRQS)
+	/*
+	 * If we are either displaying irqs, or we got called as
+	 * a graph event and private data does not exist,
+	 * then we bypass the irq check.
+	 */
+	if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
+	    (!data))
 		return 0;
 
+	depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
+
 	/*
 	 * We are inside the irq code
 	 */
@@ -925,12 +933,20 @@ static int
 check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
 {
 	int cpu = iter->cpu;
+	int *depth_irq;
 	struct fgraph_data *data = iter->private;
-	int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
 
-	if (flags & TRACE_GRAPH_PRINT_IRQS)
+	/*
+	 * If we are either displaying irqs, or we got called as
+	 * a graph event and private data does not exist,
+	 * then we bypass the irq check.
+	 */
+	if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
+	    (!data))
 		return 0;
 
+	depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
+
 	/*
 	 * We are not inside the irq code.
 	 */
-- 
1.7.1


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