[PATCH v4 3/5] stacktrace: add seq_print_stack_trace()

[Stefan Strogin <s.strogin@xxxxxxxxxxxxxxxxxxx>]

Add a function seq_print_stack_trace() which prints stacktraces to seq_files.

Signed-off-by: Stefan Strogin <stefan.strogin@xxxxxxxxx>
Reviewed-by: SeongJae Park <sj38.park@xxxxxxxxx>
---
 include/linux/stacktrace.h |  4 ++++
 kernel/stacktrace.c        | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index 0a34489..d80f2e9 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -2,6 +2,7 @@
 #define __LINUX_STACKTRACE_H
 
 #include <linux/types.h>
+#include <linux/seq_file.h>
 
 struct task_struct;
 struct pt_regs;
@@ -22,6 +23,8 @@ extern void save_stack_trace_tsk(struct task_struct *tsk,
 extern void print_stack_trace(struct stack_trace *trace, int spaces);
 extern int snprint_stack_trace(char *buf, size_t size,
 			struct stack_trace *trace, int spaces);
+extern void seq_print_stack_trace(struct seq_file *m,
+			struct stack_trace *trace, int spaces);
 
 #ifdef CONFIG_USER_STACKTRACE_SUPPORT
 extern void save_stack_trace_user(struct stack_trace *trace);
@@ -35,6 +38,7 @@ extern void save_stack_trace_user(struct stack_trace *trace);
 # define save_stack_trace_user(trace)			do { } while (0)
 # define print_stack_trace(trace, spaces)		do { } while (0)
 # define snprint_stack_trace(buf, size, trace, spaces)	do { } while (0)
+# define seq_print_stack_trace(m, trace, spaces)	do { } while (0)
 #endif
 
 #endif
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index b6e4c16..66ef6f4 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -57,6 +57,23 @@ int snprint_stack_trace(char *buf, size_t size,
 }
 EXPORT_SYMBOL_GPL(snprint_stack_trace);
 
+void seq_print_stack_trace(struct seq_file *m, struct stack_trace *trace,
+			int spaces)
+{
+	int i;
+
+	if (WARN_ON(!trace->entries))
+		return;
+
+	for (i = 0; i < trace->nr_entries; i++) {
+		unsigned long ip = trace->entries[i];
+
+		seq_printf(m, "%*c[<%p>] %pS\n", 1 + spaces, ' ',
+				(void *) ip, (void *) ip);
+	}
+}
+EXPORT_SYMBOL_GPL(seq_print_stack_trace);
+
 /*
  * Architectures that do not implement save_stack_trace_tsk or
  * save_stack_trace_regs get this weak alias and a once-per-bootup warning
-- 
2.1.0

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