The current order of calls within trace_hardirqs_off_caller() 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()
|- time_hardirqs_off()
|- trace_preemptirqsoff_hist_rcuidle()
|- __DO_TRACE()
|- rcu_dereference_sched()
|- rcu_read_lock_sched_held()
|- lock_is_held()
|- check_flags()
The order of calls within trace_hardirqs_off_caller() simplified as below:
local_irq_disable()
|- raw_local_irq_disable()
|- trace_hardirqs_off()
|- trace_hardirqs_off_caller()
|- time_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 time_hardirqs_off()
after that we clear hardirqs_enabled.
Signed-off-by: Qi Hou <[email protected]>
---
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
Please stop sending "guesswork" patches. This message to you is not
new. I am running out of avenues where I can ask you to cease and
desist; spamming maintainers like this is not acceptable. You are
one step away from being in a kill-file.
On Mon, Mar 13, 2017 at 10:00 PM, Qi Hou <[email protected]> wrote:
> The current order of calls within trace_hardirqs_off_caller() 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()
> |- time_hardirqs_off()
> |- trace_preemptirqsoff_hist_rcuidle()
> |- __DO_TRACE()
> |- rcu_dereference_sched()
> |- rcu_read_lock_sched_held()
> |- lock_is_held()
> |- check_flags()
>
> The order of calls within trace_hardirqs_off_caller() simplified as below:
>
> local_irq_disable()
> |- raw_local_irq_disable()
> |- trace_hardirqs_off()
> |- trace_hardirqs_off_caller()
> |- time_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 time_hardirqs_off()
> after that we clear hardirqs_enabled.
>
> Signed-off-by: Qi Hou <[email protected]>
> ---
> 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
>
On Tue, 14 Mar 2017 10:00:07 +0800
Qi Hou <[email protected]> wrote:
> 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;
You do realize that this breaks irqsoff tracing if lockdep ever
triggers. Right?
-- Steve
>
> @@ -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);
>
On Tue, 14 Mar 2017, Qi Hou wrote:
> The current order of calls within trace_hardirqs_off_caller() would provoke
> an "unannotated irqs-off" WARNING.
Can you finally provide information how you trigger this warning?
- Kernel version
- .config file
- test case or instructions how to provoke it?
instead of sending guess work patches and wasting everybodys time.
Thanks,
tglx
Hi, all
Sorry for everybody concerned. Please ignore this patch.
I sent this patch without my supervisor's ACKed. I missed a lot of
important information.
I'm a newbie for submitting patches to community and I should have sent
a valid patch under
my supervisor's guidance.
Execuse me, everyone.
Qi Hou
On 2017年03月14日 16:44, Thomas Gleixner wrote:
> On Tue, 14 Mar 2017, Qi Hou wrote:
>
>> The current order of calls within trace_hardirqs_off_caller() would provoke
>> an "unannotated irqs-off" WARNING.
> Can you finally provide information how you trigger this warning?
>
> - Kernel version
> - .config file
> - test case or instructions how to provoke it?
>
> instead of sending guess work patches and wasting everybodys time.
>
> Thanks,
>
> tglx
--
Best regards,
Qi Hou
Phone number: +86-10-8477-8608
Address: Floor 15, Building B, Wangjing Plaza, No.9 Zhong-Huan Nanlu, Chaoyang District