[Xenomai-core] [patch] fix rt_task_delete for cancellable rt-threads

[Xenomai-core] [patch] fix rt_task_delete for cancellable rt-threads

[Jan Kiszka]

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Hi,

no, this is not the fix for the issue I described earlier. This just
improves the behaviour of rt_task_delete in case the target is blocking
at a cancellation point (tested with standard sem_wait). With the
current version, rt_task_deletes the rt-shadow and just wakes up the
linux pthread even if the target is cancellable at that moment. With the
reordering, this is fixed and the target is actually terminated. No
major issue, though.

Jan

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Index: src/skins/native/task.c
===================================================================
--- src/skins/native/task.c	(revision 243)
+++ src/skins/native/task.c	(working copy)
@@ -203,12 +203,18 @@
 int rt_task_delete (RT_TASK *task)
 
 {
-    int err = XENOMAI_SKINCALL1(__native_muxid,
-				__native_task_delete,
-				task);
-    if (!err)
-	pthread_cancel((pthread_t)task->opaque2);
+    int err;
 
+    err = pthread_cancel((pthread_t)task->opaque2)
+    if (err)
+        return -err;
+
+    err = XENOMAI_SKINCALL1(__native_muxid,
+			    __native_task_delete,
+			    task);
+    if (err == -ESRCH)
+	return 0;
+
     return err;
 }
 

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Re: [Xenomai-core] [patch] fix rt_task_delete for cancellable rt-threads

[Jan Kiszka]

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Jan Kiszka wrote:
> Hi,
> 
> no, this is not the fix for the issue I described earlier. This just
> improves the behaviour of rt_task_delete in case the target is blocking
> at a cancellation point (tested with standard sem_wait). With the
> current version, rt_task_deletes the rt-shadow and just wakes up the
> linux pthread even if the target is cancellable at that moment. With the
> reordering, this is fixed and the target is actually terminated. No
> major issue, though.
> 
> Jan
> 
> 
> ------------------------------------------------------------------------
> 
> Index: src/skins/native/task.c
> ===================================================================
> --- src/skins/native/task.c	(revision 243)
> +++ src/skins/native/task.c	(working copy)
> @@ -203,12 +203,18 @@
>  int rt_task_delete (RT_TASK *task)
>  
>  {
> -    int err = XENOMAI_SKINCALL1(__native_muxid,
> -				__native_task_delete,
> -				task);
> -    if (!err)
> -	pthread_cancel((pthread_t)task->opaque2);
> +    int err;
>  
> +    err = pthread_cancel((pthread_t)task->opaque2)
> +    if (err)
> +        return -err;
> +
> +    err = XENOMAI_SKINCALL1(__native_muxid,
> +			    __native_task_delete,
> +			    task);
> +    if (err == -ESRCH)
> +	return 0;
> +
>      return err;
>  }
>  

Oops, fix for my patch:

--- ../src/skins/native/task.c  (Revision 251)
+++ ../src/skins/native/task.c  (Arbeitskopie)
@@ -206,7 +206,7 @@
 {
     int err;

-    err = pthread_cancel((pthread_t)task->opaque2)
+    err = pthread_cancel((pthread_t)task->opaque2);
     if (err)
         return -err;


I reorganised the code without a compiler run before posting.

Jan

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Re: [Xenomai-core] [patch] fix rt_task_delete for cancellable rt-threads

[Jan Kiszka]

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Hi Philippe,

really hope we can close this issue soon, but I managed to add another
regression with my fix (rt_task_delete(NULL) caused seg-faults, e.g. in
latency). Please apply the attached path against current SVN.

Jan

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Index: src/skins/native/task.c
===================================================================
--- src/skins/native/task.c	(Revision 251)
+++ src/skins/native/task.c	(Arbeitskopie)
@@ -206,9 +206,11 @@
 {
     int err;
 
-    err = pthread_cancel((pthread_t)task->opaque2)
-    if (err)
-        return -err;
+    if (task) {
+	err = pthread_cancel((pthread_t)task->opaque2);
+	if (err)
+	    return -err;
+    }
 
     err = XENOMAI_SKINCALL1(__native_muxid,
 			    __native_task_delete,

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