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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-06-14 16:21:43 -0400
committerSteven Rostedt <rostedt@goodmis.org>2013-06-19 23:32:07 -0400
commitde7edd31457b626e54a0b2a7e8ff4d65492f01ad (patch)
treefc98cad3155f6cded6192709c4cb496dd17282db /kernel/trace/trace.c
parentc3e13c7c0605677a2c94957b39157f4501cea9a8 (diff)
downloadop-kernel-dev-de7edd31457b626e54a0b2a7e8ff4d65492f01ad.zip
op-kernel-dev-de7edd31457b626e54a0b2a7e8ff4d65492f01ad.tar.gz
tracing: Disable tracing on warning
Add a traceoff_on_warning option in both the kernel command line as well as a sysctl option. When set, any WARN*() function that is hit will cause the tracing_on variable to be cleared, which disables writing to the ring buffer. This is useful especially when tracing a bug with function tracing. When a warning is hit, the print caused by the warning can flood the trace with the functions that producing the output for the warning. This can make the resulting trace useless by either hiding where the bug happened, or worse, by overflowing the buffer and losing the trace of the bug totally. Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.c')
-rw-r--r--kernel/trace/trace.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5f4a09c..c4c9296 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
*/
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