rcu: Deconfuse dynticks entry-exit tracing
The trace_rcu_dyntick() trace event did not print both the old and
the new value of the nesting level, and furthermore printed only
the low-order 32 bits of it. This could result in some confusion
when interpreting trace-event dumps, so this commit prints both
the old and the new value, prints the full 64 bits, and also selects
the process-entry/exit increment to print nicely in hexadecimal.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index b4e0b49..9b9bdf6 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -53,20 +53,21 @@
#include "rcutiny_plugin.h"
-static long long rcu_dynticks_nesting = LLONG_MAX / 2;
+static long long rcu_dynticks_nesting = DYNTICK_TASK_NESTING;
/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */
-static void rcu_idle_enter_common(void)
+static void rcu_idle_enter_common(long long oldval)
{
if (rcu_dynticks_nesting) {
- RCU_TRACE(trace_rcu_dyntick("--=", rcu_dynticks_nesting));
+ RCU_TRACE(trace_rcu_dyntick("--=",
+ oldval, rcu_dynticks_nesting));
return;
}
- RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting));
+ RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
if (!idle_cpu(smp_processor_id())) {
WARN_ON_ONCE(1); /* must be idle task! */
RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task",
- rcu_dynticks_nesting));
+ oldval, rcu_dynticks_nesting));
ftrace_dump(DUMP_ALL);
}
rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
@@ -79,10 +80,12 @@
void rcu_idle_enter(void)
{
unsigned long flags;
+ long long oldval;
local_irq_save(flags);
+ oldval = rcu_dynticks_nesting;
rcu_dynticks_nesting = 0;
- rcu_idle_enter_common();
+ rcu_idle_enter_common(oldval);
local_irq_restore(flags);
}
@@ -92,11 +95,13 @@
void rcu_irq_exit(void)
{
unsigned long flags;
+ long long oldval;
local_irq_save(flags);
+ oldval = rcu_dynticks_nesting;
rcu_dynticks_nesting--;
WARN_ON_ONCE(rcu_dynticks_nesting < 0);
- rcu_idle_enter_common();
+ rcu_idle_enter_common(oldval);
local_irq_restore(flags);
}
@@ -104,14 +109,15 @@
static void rcu_idle_exit_common(long long oldval)
{
if (oldval) {
- RCU_TRACE(trace_rcu_dyntick("++=", rcu_dynticks_nesting));
+ RCU_TRACE(trace_rcu_dyntick("++=",
+ oldval, rcu_dynticks_nesting));
return;
}
- RCU_TRACE(trace_rcu_dyntick("End", oldval));
+ RCU_TRACE(trace_rcu_dyntick("End", oldval, rcu_dynticks_nesting));
if (!idle_cpu(smp_processor_id())) {
WARN_ON_ONCE(1); /* must be idle task! */
RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task",
- oldval));
+ oldval, rcu_dynticks_nesting));
ftrace_dump(DUMP_ALL);
}
}
@@ -127,7 +133,7 @@
local_irq_save(flags);
oldval = rcu_dynticks_nesting;
WARN_ON_ONCE(oldval != 0);
- rcu_dynticks_nesting = LLONG_MAX / 2;
+ rcu_dynticks_nesting = DYNTICK_TASK_NESTING;
rcu_idle_exit_common(oldval);
local_irq_restore(flags);
}