Messages in this thread Patch in this message | | | From | Qi Hou <> | Subject | [PATCH] lockdep: call trace_hardirqs_off after clearing hardirqs_enabled | Date | Mon, 13 Mar 2017 18:08:48 +0800 |
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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() |- __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); -- 1.9.1
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