5 files changed, 45 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6e3b18a8afc6..729d0b9803b7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3069,6 +3069,19 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         See also Documentation/trace/ftrace.txt "trace options"
                         section.
 
+        traceoff_on_warning
+                        [FTRACE] enable this option to disable tracing when a
+                        warning is hit. This turns off "tracing_on". Tracing can
+                        be enabled again by echoing '1' into the "tracing_on"
+                        file located in /sys/kernel/debug/tracing/
+
+                        This option is useful, as it disables the trace before
+                        the WARNING dump is called, which prevents the trace to
+                        be filled with content caused by the warning output.
+
+                        This option can also be set at run time via the sysctl
+                        option:  kernel/traceoff_on_warning
+
         transparent_hugepage=
                         [KNL]
                         Format: [always|madvise|never]
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index e48ed1d7876d..9f15c0064c50 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -824,10 +824,15 @@ enum ftrace_dump_mode;
 
 extern enum ftrace_dump_mode ftrace_dump_on_oops;
 
+extern void disable_trace_on_warning(void);
+extern int __disable_trace_on_warning;
+
 #ifdef CONFIG_PREEMPT
 #define INIT_TRACE_RECURSION            .trace_recursion = 0,
 #endif
 
+#else /* CONFIG_TRACING */
+static inline void  disable_trace_on_warning(void) { }
 #endif /* CONFIG_TRACING */
 
 #ifndef INIT_TRACE_RECURSION
diff --git a/kernel/panic.c b/kernel/panic.c
index 167ec097ce8b..4cea6cc628ab 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -15,6 +15,7 @@
 #include <linux/notifier.h>
 #include <linux/module.h>
 #include <linux/random.h>
+#include <linux/ftrace.h>
 #include <linux/reboot.h>
 #include <linux/delay.h>
 #include <linux/kexec.h>
@@ -399,6 +400,8 @@ struct slowpath_args {
 static void warn_slowpath_common(const char *file, int line, void *caller,
                                  unsigned taint, struct slowpath_args *args)
 {
+        disable_trace_on_warning();
+
         printk(KERN_WARNING "------------[ cut here ]------------\n");
         printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9edcf456e0fc..5b0f18c12800 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -600,6 +600,13 @@ static struct ctl_table kern_table[] = {
                 .mode           = 0644,
                 .proc_handler   = proc_dointvec,
         },
+        {
+                .procname       = "traceoff_on_warning",
+                .data           = &__disable_trace_on_warning,
+                .maxlen         = sizeof(__disable_trace_on_warning),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec,
+        },
 #endif
 #ifdef CONFIG_MODULES
         {
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5f4a09c12e0b..c4c9296b1916 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -115,6 +115,9 @@ cpumask_var_t __read_mostly	tracing_buffer_mask;
 
 enum ftrace_dump_mode ftrace_dump_on_oops;
 
+/* When set, tracing will stop when a WARN*() is hit */
+int __disable_trace_on_warning;
+
 static int tracing_set_tracer(const char *buf);
 
 #define MAX_TRACER_SIZE         100
@@ -149,6 +152,13 @@ static int __init set_ftrace_dump_on_oops(char *str)
 }
 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
 
+static int __init stop_trace_on_warning(char *str)
+{
+        __disable_trace_on_warning = 1;
+        return 1;
+}
+__setup("traceoff_on_warning=", stop_trace_on_warning);
+
 static int __init boot_alloc_snapshot(char *str)
 {
         allocate_snapshot = true;
@@ -170,6 +180,7 @@ static int __init set_trace_boot_options(char *str)
 }
 __setup("trace_options=", set_trace_boot_options);
 
+
 unsigned long long ns2usecs(cycle_t nsec)
 {
         nsec += 500;
@@ -562,6 +573,12 @@ void tracing_off(void)
 }
 EXPORT_SYMBOL_GPL(tracing_off);
 
+void disable_trace_on_warning(void)
+{
+        if (__disable_trace_on_warning)
+                tracing_off();
+}
+
 /**
  * tracing_is_on - show state of ring buffers enabled
  */