Messages in this thread | | | Date | Mon, 13 Mar 2017 10:05:21 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] lockdep: call trace_hardirqs_off after clearing hardirqs_enabled |
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On Mon, 13 Mar 2017 18:08:48 +0800 Qi Hou <qi.hou@windriver.com> wrote:
> The current order of calls within trace_hardirqs_off() would provoke an > "unannotated irqs-off" WARNING. > > This warning was reported by check_flags() when it found that the hardirqs has > been disabled but the irq-flags state, hardirqs_enabled, has not been cleared. > > Check_flags() is called via trace_hardirqs_off(), and trace_hardirqs_off() will > be called by functions kind of local_irq_disable() if CONFIG_TRACE_IRQFLAGS has > been enabled. > > The calltrace from functions kind of local_irq_diasble() to check_flags() > simplied as below: > > local_irq_disable() > |- trace_hardirqs_off() > |- trace_hardirqs_off_caller() > |- preemptirqsoff_hist()
There is no preemptirqsoff_hist() function in the kernel.
-- Steve
> |- __DO_TRACE() > |- rcu_dereference_sched() > |- rcu_read_lock_sched_held() > |- lock_is_held() > |- check_flags() > > The order of calls within trace_hardirqs_off() can be simplified as below: > > local_irq_disable() > |- raw_local_irq_disable() > |- trace_hardirqs_off() > |- trace_hardirqs_off() --> check_flags() > |- hardirqs_enabled = 0 > > We could find that the call to check_flags() has been made between disabling > hardirqs and clearing hardirqs_enabled. That will definitely cause an > "unannotated irqs-off" warning. > > To fix this "unannotated irqs-off" warning, we must call trace_hardirqs_off() > after that we clear hardirqs_enabled. > > Signed-off-by: Qi Hou <qi.hou@windriver.com> > --- > kernel/locking/lockdep.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c > index 577f026..e8b35e4 100644 > --- a/kernel/locking/lockdep.c > +++ b/kernel/locking/lockdep.c > @@ -2627,8 +2627,6 @@ __visible void trace_hardirqs_off_caller(unsigned long ip) > { > struct task_struct *curr = current; > > - time_hardirqs_off(CALLER_ADDR0, ip); > - > if (unlikely(!debug_locks || current->lockdep_recursion)) > return; > > @@ -2649,6 +2647,8 @@ __visible void trace_hardirqs_off_caller(unsigned long ip) > debug_atomic_inc(hardirqs_off_events); > } else > debug_atomic_inc(redundant_hardirqs_off); > + > + time_hardirqs_off(CALLER_ADDR0, ip); > } > EXPORT_SYMBOL(trace_hardirqs_off_caller); >
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