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Date: Tue, 10 Mar 2009 10:56:53 +0100
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai-core] [PATCH] Suppress switch warnings while debugging
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>

Jan Kiszka wrote:
> Philippe Gerum wrote:
>> Jan Kiszka wrote:
>>> Don't raise SIGXCPU while the process is being debugged. These mode
>>> changes are expected, and reporting them doesn't provide any helpful
>>> information to the application. Rather, it may raise error storms on the
>>> application side.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@domain.hid>
>>> ---
>>>
>>>  ksrc/nucleus/shadow.c |    3 ++-
>>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/ksrc/nucleus/shadow.c b/ksrc/nucleus/shadow.c
>>> index bcf3b8b..91cf499 100644
>>> --- a/ksrc/nucleus/shadow.c
>>> +++ b/ksrc/nucleus/shadow.c
>>> @@ -1082,7 +1082,8 @@ void xnshadow_relax(int notify)
>>>  
>>>      xnstat_counter_inc(&thread->stat.ssw);    /* Account for
>>> secondary mode switch. */
>>>  
>>> -    if (notify && xnthread_test_state(thread, XNTRAPSW))
>>> +    if (notify && xnthread_test_state(thread, XNTRAPSW) &&
>>> +        !xnthread_test_state(thread, XNDEBUG))
>>>          /* Help debugging spurious relaxes. */
>>>          send_sig(SIGXCPU, current, 1);
>>>
>> I would rather identify the source of the switch and clear the notify
>> flag appropriately from the relax call site.
> 
> Sorry, don't get this: What flag do you want to clear? XNTRAPSW?
>

The "notify" parameter should set by the call site to tell xnshadow_relax() 
whether we want the SIGXCPU signal to be sent or not. I would rather identify 
which call site introduces the issue, and fix the notify parameter accordingly. 
Did you track the issue down to request_syscall_restart() for instance? In which 
case, we should rather test XNDEBUG there, and set the notify flag passed to 
xnshadow_relax() appropriately.

> Jan
> 


-- 
Philippe.