Possible problem with CONFIGURE_MAXIMUM_SEMAPHORES succeeding

[Eric Norum]

The actual number of semaphores configured into the system depends upon more than just the value you provide for CONFIGURE_MAXIMUM_SEMAPHORES.
Here's the salient code from confdefs.h:

 #define CONFIGURE_SEMAPHORES \
    (CONFIGURE_MAXIMUM_SEMAPHORES + CONFIGURE_LIBIO_SEMAPHORES + \
      CONFIGURE_TERMIOS_SEMAPHORES + CONFIGURE_LIBBLOCK_SEMAPHORES)

Thus your test is merely soaking up some of the semaphores configured for other possible use.



On Feb 10, 2011, at 1:15 PM, Andrei Chichak wrote:

> Hi all,
> 
> I was adding another semaphore to my code and decided to test the semaphore create failure case first. I added the create without incrementing the maximum number of semaphores that was configured. The create succeeded rather than failed.
> 
> I created 4 semaphores with the maximum set to 3. All returned rtems_status_code == 0. I set the maximum to 2, same. I set the maximum to 1, same. I set the maximum to 0, same result.
> 
> This is running on an Axiom CML5282 using RTEMS 4.9.4 and a BSP that is heavily based on the AV5282 and UC5282 BSPs.
> 
> Any ideas?
> 
> 
> 
> I started stripping out code until my program generates this:
> 
> 
> create sem1 semaphore returned with 0
> 
> create sem2 semaphore returned with 0
> 
> create sem3 semaphore returned with 0
> 
> create sem4 semaphore returned with 0
> 
> 
> From this (only comments have been removed):
> 
> 
> #include <rtems.h>
> 
> rtems_task Init(rtems_task_argument ignored);
> 
> #include <bsp.h>
> 
> #define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
> #define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
> #define CONFIGURE_MAXIMUM_TASKS				1
> #define CONFIGURE_MAXIMUM_MESSAGE_QUEUES	0
> 
> #define CONFIGURE_MAXIMUM_SEMAPHORES		0
> 
> #define CONFIGURE_MAXIMUM_TIMERS			0
> #define CONFIGURE_MAXIMUM_PARTITIONS		0
> #define CONFIGURE_MAXIMUM_DRIVERS			20
> 
> #define STACK_CHECKER_ON
> 
> #define CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS 20
> 
> #define CONFIGURE_RTEMS_INIT_TASKS_TABLE
> #define CONFIGURE_INIT
> 
> #include <rtems/confdefs.h>
> 
> static rtems_id sem1;
> static rtems_id sem2;
> static rtems_id sem3;
> static rtems_id sem4;
> 
> rtems_task Init(rtems_task_argument ignored) {
> 
> 	rtems_status_code status;
> 
> 	status = rtems_semaphore_create( rtems_build_name('S','E','M','1'),
> 			1,
> 			RTEMS_PRIORITY | RTEMS_BINARY_SEMAPHORE | RTEMS_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL,
> 			0,
> 			&sem1);
> 
> 	printk("create sem1 semaphore returned with %d\n", status);
> 
> 	status = rtems_semaphore_create( rtems_build_name('S','E','M','2'),
> 			1,
> 			RTEMS_PRIORITY | RTEMS_BINARY_SEMAPHORE | RTEMS_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL,
> 			0,
> 			&sem2);
> 
> 	printk("create sem2 semaphore returned with %d\n", status);
> 
> 	status = rtems_semaphore_create( rtems_build_name('S','E','M','3'),
> 			1,
> 			RTEMS_PRIORITY | RTEMS_BINARY_SEMAPHORE | RTEMS_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL,
> 			0,
> 			&sem3);
> 
> 	printk("create sem3 semaphore returned with %d\n", status);
> 
> 	status = rtems_semaphore_create( rtems_build_name('S','E','M','4'),
> 			1,
> 			RTEMS_PRIORITY | RTEMS_BINARY_SEMAPHORE | RTEMS_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL,
> 			0,
> 			&sem4);
> 
> 	printk("create sem4 semaphore returned with %d\n", status);
> 
> 	status = rtems_task_delete( RTEMS_SELF);
> 	exit(0);
> }
> 
> 
> 
> _______________________________________________
> rtems-users mailing list
> rtems-users at rtems.org
> http://www.rtems.org/mailman/listinfo/rtems-users

-- 
Eric Norum
wenorum at lbl.gov

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rtems.org/pipermail/users/attachments/20110210/5645c96a/attachment-0001.html>