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From: Peter Rehley <peter AT rehley DOT net>
Subject: Re: pthreads, cygwin and pthread_mutex_lock not blocking
Date: Tue, 7 Jun 2005 10:22:11 -0700
To: "Cygwin List'" <cygwin AT cygwin DOT com>
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Any comments about this?

On Jun 2, 2005, at 11:22 AM, Peter Rehley wrote:

> Here is a patch to thread.cc that allows _lock to process signals.  
> The patch is against the 1.178 version of thread.cc found in cvs.
>
> --- thread.cc.orig      Thu Jun  2 11:17:39 2005
> +++ thread.cc   Thu Jun  2 11:20:00 2005
> @@ -1543,8 +1543,24 @@
>      }
>    else
>      {
> -      WaitForSingleObject (win32_obj_id, INFINITE);
> -      set_owner (self);
> +      //WaitForSingleObject (win32_obj_id, INFINITE);
> +      //set_owner (self);
> +      bool loop = true;
> +      do
> +       switch (pthread::cancelable_wait (win32_obj_id, INFINITE, 
> false, true))
> +         {
> +         case WAIT_OBJECT_0:
> +            set_owner (self);
> +            loop=false;
> +           break;
> +         case WAIT_SIGNALED:
> +           _my_tls.call_signal_handler ();
> +           break;
> +         default:
> +           // should never happen
> +           return EINVAL;
> +         }
> +      while (loop);
>      }
>
>    return result;
>
> On Jun 1, 2005, at 6:17 PM, Peter Rehley wrote:
>
>> Here is the patch to pthread.h
>>
>> hummingbird:~/MontaVista/tmp prehley$ diff -u pthread.h.cygwin 
>> pthread.h.new
>> --- pthread.h.cygwin    Wed Jun  1 18:15:40 2005
>> +++ pthread.h.new       Wed Jun  1 18:06:49 2005
>> @@ -53,12 +53,12 @@
>>  #define PTHREAD_MUTEX_RECURSIVE 0
>>  #define PTHREAD_MUTEX_ERRORCHECK 1
>>  #define PTHREAD_MUTEX_NORMAL 2
>> -#define PTHREAD_MUTEX_DEFAULT PTHREAD_MUTEX_ERRORCHECK
>> +#define PTHREAD_MUTEX_DEFAULT PTHREAD_MUTEX_NORMAL
>>  /* this should be too low to ever be a valid address */
>>  #define PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP (pthread_mutex_t)18
>>  #define PTHREAD_NORMAL_MUTEX_INITIALIZER_NP (pthread_mutex_t)19
>>  #define PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP (pthread_mutex_t)20
>> -#define PTHREAD_MUTEX_INITIALIZER 
>> PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
>> +#define PTHREAD_MUTEX_INITIALIZER PTHREAD_NORMAL_MUTEX_INITIALIZER_NP
>>  #define PTHREAD_ONCE_INIT { PTHREAD_MUTEX_INITIALIZER, 0 }
>>  #define PTHREAD_PRIO_INHERIT
>>  #define PTHREAD_PRIO_NONE
>> @@ -202,4 +202,3 @@
>>  #endif
>>
>>  #endif /* _PTHREAD_H */
>> -
>>
>> On Jun 1, 2005, at 5:22 PM, Peter Rehley wrote:
>>
>>>
>>>
>>> On May 31, 2005, at 10:50 AM, David Rothenberger wrote:
>>>
>>>> On 5/31/2005 10:15 AM, Peter Rehley wrote:
>>>>> Well, here is a simple test case, but turns out I wasn't using the 
>>>>> latest version.  I was having the problem on 1.5.12,  I haven't 
>>>>> been able to get a good build with cygwin 1.5.17-1.  It builds and 
>>>>> I can run the install script, but when I put the dll in place I 
>>>>> see the message "cygheap magic number mismatch detected", and gcc 
>>>>> doesn't want to work.
>>>>
>>>> I had a similar problem (see 
>>>> <http://cygwin.com/ml/cygwin/2005-05/msg01251.html>). It turned out 
>>>> it was because I was using the latest release of binutils. Try 
>>>> rolling back to the previous release.
>>>>
>>> Ok, I rolled binutils to 20041229, rebuilt and copied the new dll.  
>>> It's having the same issue that I see in 1.5.12.  When I debug the 
>>> program, I see that the signal is being sent, but it doesn't get 
>>> executed.
>>>
>>> I've looked at the cygwin code, and I have noticed that the sleep 
>>> (nanosleep) is calling pthread::cancelable_wait, and that will call 
>>> WaitForMultipleObjects.  However, in pthread_mutex::_lock, it's only 
>>> using WaitForSingleObject.  I'm wondering if something like 
>>> WaitForMultipleObjects should be added to the lock function so that 
>>> signals (SIGCHLD, in my case) can be handled.
>>>
>>> It's just a guess since I'm not an expert with this code.
>>>
>>> Enjoy,
>>> Peter
>>> -------------------------------
>>> A Møøse once bit my sister
>>>
>>>
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>>>
>>>
>>>
>> Enjoy,
>> Peter
>> -------------------------------
>> A Møøse once bit my sister
>>
>>
>> --
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>>
>>
>>
> Enjoy,
> Peter
> -------------------------------
> A Møøse once bit my sister
>
>
> --
> Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
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>
>
>
Enjoy,
Peter
-------------------------------
A Møøse once bit my sister


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