tracing: Remove access to trace_flags in trace_printk.c

In the effort to move the global trace_flags to the tracing instances, the
direct access to trace_flags must be removed from trace_printk.c

Instead, add a new trace_printk_enabled boolean that is set by a new access
function trace_printk_control(), that will enable or disable trace_printk.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 14 insertions, 5 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 991bab9b79d2..d98789b112c6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3555,8 +3555,10 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
 #endif
         }
 
-        if (mask == TRACE_ITER_PRINTK)
+        if (mask == TRACE_ITER_PRINTK) {
                 trace_printk_start_stop_comm(enabled);
+                trace_printk_control(enabled);
+        }
 
         return 0;
 }
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 07155652254d..33d1e5384481 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1318,6 +1318,7 @@ extern const char *__stop___trace_bprintk_fmt[];
 extern const char *__start___tracepoint_str[];
 extern const char *__stop___tracepoint_str[];
 
+void trace_printk_control(bool enabled);
 void trace_printk_init_buffers(void);
 void trace_printk_start_comm(void);
 int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index 36c1455b7567..1c2b28536feb 100644
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -178,6 +178,12 @@ static inline void format_mod_start(void) { }
 static inline void format_mod_stop(void) { }
 #endif /* CONFIG_MODULES */
 
+static bool __read_mostly trace_printk_enabled = true;
+
+void trace_printk_control(bool enabled)
+{
+        trace_printk_enabled = enabled;
+}
 
 __initdata_or_module static
 struct notifier_block module_trace_bprintk_format_nb = {
@@ -192,7 +198,7 @@ int __trace_bprintk(unsigned long ip, const char *fmt, ...)
         if (unlikely(!fmt))
                 return 0;
 
-        if (!(trace_flags & TRACE_ITER_PRINTK))
+        if (!trace_printk_enabled)
                 return 0;
 
         va_start(ap, fmt);
@@ -207,7 +213,7 @@ int __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap)
         if (unlikely(!fmt))
                 return 0;
 
-        if (!(trace_flags & TRACE_ITER_PRINTK))
+        if (!trace_printk_enabled)
                 return 0;
 
         return trace_vbprintk(ip, fmt, ap);
@@ -219,7 +225,7 @@ int __trace_printk(unsigned long ip, const char *fmt, ...)
         int ret;
         va_list ap;
 
-        if (!(trace_flags & TRACE_ITER_PRINTK))
+        if (!trace_printk_enabled)
                 return 0;
 
         va_start(ap, fmt);
@@ -231,7 +237,7 @@ EXPORT_SYMBOL_GPL(__trace_printk);
 
 int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap)
 {
-        if (!(trace_flags & TRACE_ITER_PRINTK))
+        if (!trace_printk_enabled)
                 return 0;
 
         return trace_vprintk(ip, fmt, ap);