tracing: Check if tracing is enabled in trace_puts()

If trace_puts() is used very early in boot up, it can crash the machine
if it is called before the ring buffer is allocated. If a trace_printk()
is used with no arguments, then it will be converted into a trace_puts()
and suffer the same fate.

Cc: stable@vger.kernel.org # 3.10+
Fixes: 09ae72348ecc "tracing: Add trace_puts() for even faster trace_printk() tracing"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7857ea9b3b9c..815c878f409b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -455,6 +455,9 @@ int __trace_puts(unsigned long ip, const char *str, int size)
         unsigned long irq_flags;
         int alloc;
 
+        if (unlikely(tracing_selftest_running || tracing_disabled))
+                return 0;
+
         alloc = sizeof(*entry) + size + 2; /* possible \n added */
 
         local_save_flags(irq_flags);
@@ -495,6 +498,9 @@ int __trace_bputs(unsigned long ip, const char *str)
         unsigned long irq_flags;
         int size = sizeof(struct bputs_entry);
 
+        if (unlikely(tracing_selftest_running || tracing_disabled))
+                return 0;
+
         local_save_flags(irq_flags);
         buffer = global_trace.trace_buffer.buffer;
         event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,