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rcu: Deconfuse dynticks entry-exit tracing

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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>
This commit is contained in:
Paul E. McKenney 2011-10-31 15:01:54 -07:00 • committed by Paul E. McKenney
parent 9ceae0e248
commit 4145fa7fbe
4 changed files with 53 additions and 32 deletions
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28
kernel/rcutiny.c
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@ -53,20 +53,21 @@ static void __call_rcu(struct rcu_head *head,
#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 @@ static void rcu_idle_enter_common(void)
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_idle_enter(void)
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 @@ void rcu_irq_exit(void)
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 @@ void rcu_idle_exit(void)
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);
}