tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputs

commit 8abfb872 upstream.

Currently trace option stacktrace is not applicable for
trace_printk with constant string argument, the reason is
in __trace_puts/__trace_bputs ftrace_trace_stack is missing.

In contrast, when using trace_printk with non constant string
argument(will call into __trace_printk/__trace_bprintk), then
trace option stacktrace is workable, this inconstant result
will confuses users a lot.

Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.comSigned-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

kernel/trace/trace.c

@@ -454,6 +454,9 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	struct print_entry *entry;
 	unsigned long irq_flags;
 	int alloc;
+	int pc;
+
+	pc = preempt_count();
 
 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
@@ -463,7 +466,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 	local_save_flags(irq_flags);
 	buffer = global_trace.trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc, 
-					  irq_flags, preempt_count());
+					  irq_flags, pc);
 	if (!event)
 		return 0;
 
@@ -480,6 +483,7 @@ int __trace_puts(unsigned long ip, const char *str, int size)
 		entry->buf[size] = '\0';
 
 	__buffer_unlock_commit(buffer, event);
+	ftrace_trace_stack(buffer, irq_flags, 4, pc);
 
 	return size;
 }
@@ -497,6 +501,9 @@ int __trace_bputs(unsigned long ip, const char *str)
 	struct bputs_entry *entry;
 	unsigned long irq_flags;
 	int size = sizeof(struct bputs_entry);
+	int pc;
+
+	pc = preempt_count();
 
 	if (unlikely(tracing_selftest_running || tracing_disabled))
 		return 0;
@@ -504,7 +511,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	local_save_flags(irq_flags);
 	buffer = global_trace.trace_buffer.buffer;
 	event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
-					  irq_flags, preempt_count());
+					  irq_flags, pc);
 	if (!event)
 		return 0;
 
@@ -513,6 +520,7 @@ int __trace_bputs(unsigned long ip, const char *str)
 	entry->str			= str;
 
 	__buffer_unlock_commit(buffer, event);
+	ftrace_trace_stack(buffer, irq_flags, 4, pc);
 
 	return 1;
 }