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-rw-r--r--include/linux/ftrace.h4
-rw-r--r--kernel/sysctl.c2
-rw-r--r--kernel/trace/trace.c78
-rw-r--r--kernel/trace/trace_events.c40
4 files changed, 83 insertions, 41 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index b3d34d3e0e7e..8700049fd0e5 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -945,6 +945,10 @@ extern int __disable_trace_on_warning;
#define INIT_TRACE_RECURSION .trace_recursion = 0,
#endif
+int tracepoint_printk_sysctl(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
+
#else /* CONFIG_TRACING */
static inline void disable_trace_on_warning(void) { }
#endif /* CONFIG_TRACING */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 706309f9ed84..6ccc60dfbc7a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -634,7 +634,7 @@ static struct ctl_table kern_table[] = {
.data = &tracepoint_printk,
.maxlen = sizeof(tracepoint_printk),
.mode = 0644,
- .proc_handler = proc_dointvec,
+ .proc_handler = tracepoint_printk_sysctl,
},
#endif
#ifdef CONFIG_KEXEC_CORE
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 490533726b54..725e8b2c453f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -69,6 +69,7 @@ bool __read_mostly tracing_selftest_disabled;
/* Pipe tracepoints to printk */
struct trace_iterator *tracepoint_print_iter;
int tracepoint_printk;
+static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);
/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
@@ -2116,6 +2117,81 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
}
EXPORT_SYMBOL_GPL(trace_event_buffer_lock_reserve);
+static DEFINE_SPINLOCK(tracepoint_iter_lock);
+static DEFINE_MUTEX(tracepoint_printk_mutex);
+
+static void output_printk(struct trace_event_buffer *fbuffer)
+{
+ struct trace_event_call *event_call;
+ struct trace_event *event;
+ unsigned long flags;
+ struct trace_iterator *iter = tracepoint_print_iter;
+
+ /* We should never get here if iter is NULL */
+ if (WARN_ON_ONCE(!iter))
+ return;
+
+ event_call = fbuffer->trace_file->event_call;
+ if (!event_call || !event_call->event.funcs ||
+ !event_call->event.funcs->trace)
+ return;
+
+ event = &fbuffer->trace_file->event_call->event;
+
+ spin_lock_irqsave(&tracepoint_iter_lock, flags);
+ trace_seq_init(&iter->seq);
+ iter->ent = fbuffer->entry;
+ event_call->event.funcs->trace(iter, 0, event);
+ trace_seq_putc(&iter->seq, 0);
+ printk("%s", iter->seq.buffer);
+
+ spin_unlock_irqrestore(&tracepoint_iter_lock, flags);
+}
+
+int tracepoint_printk_sysctl(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int save_tracepoint_printk;
+ int ret;
+
+ mutex_lock(&tracepoint_printk_mutex);
+ save_tracepoint_printk = tracepoint_printk;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+
+ /*
+ * This will force exiting early, as tracepoint_printk
+ * is always zero when tracepoint_printk_iter is not allocated
+ */
+ if (!tracepoint_print_iter)
+ tracepoint_printk = 0;
+
+ if (save_tracepoint_printk == tracepoint_printk)
+ goto out;
+
+ if (tracepoint_printk)
+ static_key_enable(&tracepoint_printk_key.key);
+ else
+ static_key_disable(&tracepoint_printk_key.key);
+
+ out:
+ mutex_unlock(&tracepoint_printk_mutex);
+
+ return ret;
+}
+
+void trace_event_buffer_commit(struct trace_event_buffer *fbuffer)
+{
+ if (static_key_false(&tracepoint_printk_key.key))
+ output_printk(fbuffer);
+
+ event_trigger_unlock_commit(fbuffer->trace_file, fbuffer->buffer,
+ fbuffer->event, fbuffer->entry,
+ fbuffer->flags, fbuffer->pc);
+}
+EXPORT_SYMBOL_GPL(trace_event_buffer_commit);
+
void trace_buffer_unlock_commit_regs(struct trace_array *tr,
struct ring_buffer *buffer,
struct ring_buffer_event *event,
@@ -7977,6 +8053,8 @@ void __init trace_init(void)
kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
if (WARN_ON(!tracepoint_print_iter))
tracepoint_printk = 0;
+ else
+ static_key_enable(&tracepoint_printk_key.key);
}
tracer_alloc_buffers();
trace_event_init();
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ba67ede48822..d35fc2b0d304 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -283,46 +283,6 @@ void *trace_event_buffer_reserve(struct trace_event_buffer *fbuffer,
}
EXPORT_SYMBOL_GPL(trace_event_buffer_reserve);
-static DEFINE_SPINLOCK(tracepoint_iter_lock);
-
-static void output_printk(struct trace_event_buffer *fbuffer)
-{
- struct trace_event_call *event_call;
- struct trace_event *event;
- unsigned long flags;
- struct trace_iterator *iter = tracepoint_print_iter;
-
- if (!iter)
- return;
-
- event_call = fbuffer->trace_file->event_call;
- if (!event_call || !event_call->event.funcs ||
- !event_call->event.funcs->trace)
- return;
-
- event = &fbuffer->trace_file->event_call->event;
-
- spin_lock_irqsave(&tracepoint_iter_lock, flags);
- trace_seq_init(&iter->seq);
- iter->ent = fbuffer->entry;
- event_call->event.funcs->trace(iter, 0, event);
- trace_seq_putc(&iter->seq, 0);
- printk("%s", iter->seq.buffer);
-
- spin_unlock_irqrestore(&tracepoint_iter_lock, flags);
-}
-
-void trace_event_buffer_commit(struct trace_event_buffer *fbuffer)
-{
- if (tracepoint_printk)
- output_printk(fbuffer);
-
- event_trigger_unlock_commit(fbuffer->trace_file, fbuffer->buffer,
- fbuffer->event, fbuffer->entry,
- fbuffer->flags, fbuffer->pc);
-}
-EXPORT_SYMBOL_GPL(trace_event_buffer_commit);
-
int trace_event_reg(struct trace_event_call *call,
enum trace_reg type, void *data)
{