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Date: Tue, 02 Mar 2010 13:32:02 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-core] [Xenomai-git] Jan Kiszka : Native: Fix return
 code of in-kernel rt_cond_wait[_until]
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: Xenomai core <Xenomai-core@domain.hid>

Jan Kiszka wrote:
> Gilles Chanteperdrix wrote:
>> GIT version control wrote:
>>> Module: xenomai-jki
>>> Branch: for-upstream
>>> Commit: f1dfda551b6997f74141986759932e2723a9f024
>>> URL:    http://git.xenomai.org/?p=xenomai-jki.git;a=commit;h=f1dfda551b6997f74141986759932e2723a9f024
>>>
>>> Author: Jan Kiszka <jan.kiszka@domain.hid>
>>> Date:   Tue Mar  2 13:17:35 2010 +0100
>>>
>>> Native: Fix return code of in-kernel rt_cond_wait[_until]
>>>
>>> In rt_cond_wait_inner, do not let rt_cond_wait_epilogue overwrite the
>>> primary error code of rt_cond_wait_prologue. This restores the in-kernel
>>> semantics of rt_cond_wait[_until] that were valid before 97323b3287.
>>>
>>> Signed-off-by: Jan Kiszka <jan.kiszka@domain.hid>
>>>
>>> ---
>>>
>>>  ksrc/skins/native/cond.c |    8 ++++----
>>>  1 files changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/ksrc/skins/native/cond.c b/ksrc/skins/native/cond.c
>>> index 10727d1..2dc0069 100644
>>> --- a/ksrc/skins/native/cond.c
>>> +++ b/ksrc/skins/native/cond.c
>>> @@ -472,10 +472,10 @@ static int rt_cond_wait_inner(RT_COND *cond, RT_MUTEX *mutex,
>>>  	err = rt_cond_wait_prologue(cond, mutex, &lockcnt, 
>>>  				    timeout_mode, timeout);
>>>  
>>> -	if(!err || err == -ETIMEDOUT || err == -EINTR)
>>> -		do {
>>> -			err = rt_cond_wait_epilogue(mutex, lockcnt);
>>> -		} while (err == -EINTR);
>>> +	if (!err || err == -ETIMEDOUT || err == -EINTR) {
>>> +		while (rt_cond_wait_epilogue(mutex, lockcnt) == -EINTR)
>>> +			; /* empty */
>>> +	}
>> Not ok. If rt_cond_wait_epilogue returns an error other than -EINTR, we
>> want this error to be returned.
> 
> As I said: This is what we used to do in 2.4 (and early 2.5-rc), and due
> to the absence of spec on this topic, I would vote for restoring old
> behavior.

if rt_cond_wait_epilogue returns an error other than -EINTR, there is an
error to be signaled, so, it should be returned to the user, not 0 or
-ETIMEDOUT which would let the user think that he got the mutex back,
whereas the mutex is probably not properly locked.

> 
> Jan
> 


-- 
					    Gilles.