On Wed, 28 Nov 2018 16:00:21 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Wed, 28 Nov 2018 15:39:31 -0500
> Joe Lawrence <joe.lawrence@xxxxxxxxxx> wrote:
>
> > Hi Steve,
> >
> > With your ftrace/urgent branch linked above, if I try a quick
> > function_graph test like the following:
> >
> > SYSFS=/sys/kernel/debug/tracing
> >
> > echo 0 > "$SYSFS/tracing_on"
> > echo cmdline_proc_show > "$SYSFS/set_graph_function"
> > echo function_graph > "$SYSFS/current_tracer"
> > echo 1 > "$SYSFS/tracing_on"
> >
> > I see a bunch of scheduler interrupt functions in the trace/trace_pipe
> > without even invoking cmdline_proc_show().
> >
> > This tests works as expected with Linux 4.20-rc3 though:
> >
> > % cat /sys/kernel/debug/tracing/trace_pipe
> > 2) | cmdline_proc_show() {
> > 2) 0.320 us | seq_puts();
> > 2) 0.030 us | seq_putc();
> > 2) 1.352 us | }
> >
> > Operator error, or did the patchset break something?
>
> Nope, that does seem to be a bug :-/
>
Does this patch fix it for you?
-- Steve
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3b8c0e24ab30..1c8f4aa7020e 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -512,6 +512,9 @@ enum {
* can only be modified by current, we can reuse trace_recursion.
*/
TRACE_IRQ_BIT,
+
+ /* Set if the function is in the set_graph_function file */
+ TRACE_GRAPH_BIT,
};
#define trace_recursion_set(bit) do { (current)->trace_recursion |= (1<<(bit)); } while (0)
@@ -855,6 +858,8 @@ static inline int ftrace_graph_addr(unsigned long addr)
}
if (ftrace_lookup_ip(ftrace_graph_hash, addr)) {
+
+ trace_recursion_set(TRACE_GRAPH_BIT);
/*
* If no irqs are to be traced, but a set_graph_function
* is set, and called by an interrupt handler, we still
@@ -901,7 +906,8 @@ extern unsigned int fgraph_max_depth;
static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
{
/* trace it when it is-nested-in or is a function enabled. */
- return !(trace->depth || ftrace_graph_addr(trace->func)) ||
+ return !(trace_recursion_test(TRACE_GRAPH_BIT) ||
+ ftrace_graph_addr(trace->func)) ||
(trace->depth < 0) ||
(fgraph_max_depth && trace->depth >= fgraph_max_depth);
}
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 2561460d7baf..69fbb6225637 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -509,6 +509,9 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
int cpu;
int pc;
+ if (!trace->depth)
+ trace_recursion_clear(TRACE_GRAPH_BIT);
+
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
@@ -532,6 +535,8 @@ void set_graph_array(struct trace_array *tr)
static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
{
+ if (!trace->depth)
+ trace_recursion_clear(TRACE_GRAPH_BIT);
if (tracing_thresh &&
(trace->rettime - trace->calltime < tracing_thresh))
return;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index b7357f9f82a3..b20bf076ce7f 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -208,6 +208,9 @@ static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
unsigned long flags;
int pc;
+ if (!trace->depth)
+ trace_recursion_clear(TRACE_GRAPH_BIT);
+
if (!func_prolog_dec(tr, &data, &flags))
return;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index a86b303e6c67..069867f4eae6 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -270,6 +270,9 @@ static void wakeup_graph_return(struct ftrace_graph_ret *trace)
unsigned long flags;
int pc;
+ if (!trace->depth)
+ trace_recursion_clear(TRACE_GRAPH_BIT);
+
if (!func_prolog_preempt_disable(tr, &data, &pc))
return;
