[Xenomai-help] rt_heap_delete in asynchronous context

[Xenomai-help] rt_heap_delete in asynchronous context

[Nathaniel J Villaume]

Hi, 

I have a simple user-space program (see below) that tries to
create a heap. If the heap already exists, then the program tries
to delete it. I have no other threads binding to the heap.

I can create, but not delete the heap. The error returned is
-EPERM. According to the API manual, this means the call occurred
in an asynchronous context. What does this mean, exactly? How
should I delete this heap? 

Any advice?

BTW, superb job on the documentation, it's made my learning curve
easy/straight-forward. 

Thanks,

Nate
/*************************************************/
/*! @file
  @brief 
  File shows how to allocate heap memory from user-space 
 */
#include "native/heap.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

RT_HEAP heap;
const char hp_name[]="heap1";
size_t hp_size = 500000;
RT_HEAP_INFO hp_info;

/*Map error codes to human-readable strings*/
void xeno_error_lookup(const char* msg, int err);

int
main( void )
{
  int err = 0;
  err = rt_heap_create( &heap, hp_name, hp_size, H_SHARED);
  if (err)
  {
    printf("Couldn't create the heap\n");
    if (-EEXIST == err)
    { 
      printf("Deleting heap....\n");
      err = rt_heap_delete( &heap);
      if (err)
      {
        xeno_error_lookup("Couldn't delete heap.", err);
      }
    }
    exit(err);
  }
  return err;
}

void xeno_error_lookup(const char* msg, int err)
{
  char* pc=0;
  switch (err)
  {
    case -EINVAL:
      pc = "EINVAL"; 
      break;
    case -EIDRM:
      pc = "EIDRM"; 
      break;
    case -EPERM:
      pc = "EPERM"; 
      break;
  }
  printf("%s: %d => %s\n", msg, err, pc);
}

Re: [Xenomai-help] rt_heap_delete in asynchronous context

[Gilles Chanteperdrix]

Nathaniel J Villaume wrote:
 > Hi, 
 > 
 > I have a simple user-space program (see below) that tries to
 > create a heap. If the heap already exists, then the program tries
 > to delete it. I have no other threads binding to the heap.
 > 
 > I can create, but not delete the heap. The error returned is
 > -EPERM. According to the API manual, this means the call occurred
 > in an asynchronous context. What does this mean, exactly? How
 > should I delete this heap? 
 > 
 > Any advice?

You should not try and delete a heap if you did not succeed in creating
or binding it. The contents of the RT_HEAP object are uninitialized
when rt_heap_create fails, rt_heap_delete call munmap passing the
contents of this uninitialized object, and munmap returns -1 with errno
set to EINVAL. rt_heap_delete should be fixed to return -errno in this
case, but you should bind the heap before deleting it.

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-help] rt_heap_delete in asynchronous context

[Nathaniel J Villaume]

Gilles, 

Thanks for the reply. Sure enough, binding to the heap allows me
to delete it.  I wanted to update the documentation, but I'm not
sure I understand it well enough.  Here's my attempt
 --I hope it clarifies rather than obscures! :

--- ksrc/skins/native/heap.c 2006-04-09 14:03:50.000000000 -0700
+++ ksrc/skins/native/heap.c.new 2006-05-27 22:54:44.000000000 -0700
@@ -351,7 +351,8 @@
  * - -EIDRM is returned if @a heap is a deleted heap descriptor.
  *
  * - -EPERM is returned if this service was called from an
- * asynchronous context.
+ * asynchronous context. The heap may first need to be
associated with the
+ * calling process using rt_heap_bind().
  *
  * Environments:
  *