Mutex
==============


.. panels::
        :container: container pb-4
        :column: col-lg-12 p-2
        :card: shadow

        Topics in this section,

                * :ref:`Version Info <FreebsdDeviceDriver_basic_fdd_mutex_1>`

                * :ref:`Learnings in this section <FreebsdDeviceDriver_basic_fdd_mutex_2>`

                * :ref:`Complete program : mutex.c <FreebsdDeviceDriver_basic_fdd_mutex_3>`

                * :ref:`Makefile <FreebsdDeviceDriver_basic_fdd_mutex_4>`

                * :ref:`Compile Program <FreebsdDeviceDriver_basic_fdd_mutex_5>`

                * :ref:`Load the module <FreebsdDeviceDriver_basic_fdd_mutex_6>`

                * :ref:`Check if the module is loaded successfully <FreebsdDeviceDriver_basic_fdd_mutex_7>`

                * :ref:`Check what happened on module load <FreebsdDeviceDriver_basic_fdd_mutex_8>`

                * :ref:`Unload the module <FreebsdDeviceDriver_basic_fdd_mutex_9>`

                * :ref:`Check if the module is unloaded successfully <FreebsdDeviceDriver_basic_fdd_mutex_10>`

                * :ref:`Check what happened on module unload <FreebsdDeviceDriver_basic_fdd_mutex_11>`



.. _FreebsdDeviceDriver_basic_fdd_mutex_1:

.. tab-set::
 
    .. tab-item:: Version Info

        =============================== =======================================
        #                               Version
        =============================== =======================================
        Freebsd                         14.1.0
        =============================== =======================================



.. _FreebsdDeviceDriver_basic_fdd_mutex_2:

.. tab-set::

    .. tab-item:: Learnings in this section

        * In this program, you are going to learn

        .. panels::
                :container: container pb-4
                :column: col-lg-12 p-2
                :card: shadow

                * How to use mutex in kernel module ?



.. _FreebsdDeviceDriver_basic_fdd_mutex_3:

.. tab-set::

   .. tab-item:: mutex.c

        .. literalinclude:: mutex/mutex.c
                :language: c
                :linenos:



.. _FreebsdDeviceDriver_basic_fdd_mutex_4:

.. tab-set::

   .. tab-item:: Makefile

        .. literalinclude:: mutex/Makefile
                :language: c
                :linenos:



.. _FreebsdDeviceDriver_basic_fdd_mutex_5:

.. tab-set::

    .. tab-item:: Compile Program
        
        .. code-block:: c
                :linenos:
                :emphasize-lines: 1, 5, 9, 12
                
                $ pwd
                basic_device_drivers/mutex


                $ ls
                mutex.c  Makefile 


                $ make


                $ ls
		.depend.mutex.o export_syms     machine         mutex.o         opt_global.h
		Makefile        i386            mutex.c         mutex_module.ko x86



.. _FreebsdDeviceDriver_basic_fdd_mutex_6:

.. tab-set::

    .. tab-item:: Load the module 

        * Load the module using kldload
        
        .. code-block:: c
                :linenos:
                :emphasize-lines: 1

                $ kldload -v ./mutex_module.ko
		Loaded ./mutex_module.ko, id=8		



.. _FreebsdDeviceDriver_basic_fdd_mutex_7:

.. tab-set::

    .. tab-item:: Check if the module is loaded successfully

        * Run kldstat command to check the loaded modules
        
        .. code-block:: c
                :linenos:
                :emphasize-lines: 1, 10
                
                $ kldstat
                Id Refs Address                Size Name
                 1   29 0xffffffff80200000  1f6c698 kernel
                 2    1 0xffffffff8216d000   772c70 zfs.ko
                 3    1 0xffffffff828e1000     7850 cryptodev.ko
                 4    1 0xffffffff83218000     3220 intpm.ko
                 5    1 0xffffffff8321c000     2178 smbus.ko
                 6    1 0xffffffff8321f000     3360 uhid.ko
                 7    1 0xffffffff83223000     3360 wmt.ko
                 8    1 0xffffffff83227000     20d4 mutex_module.ko




.. _FreebsdDeviceDriver_basic_fdd_mutex_8:

.. tab-set::

    .. tab-item:: Check what happened on module load
        
        * Run dmesg command to check the kernel logs

        .. code-block:: c
                :linenos:
                :emphasize-lines: 1
                
                $ dmesg
		Module loaded
		Count = 0
		Count = 1




.. _FreebsdDeviceDriver_basic_fdd_mutex_9:

.. tab-set::

    .. tab-item:: Unload the module 

        * Unload the module using kldunload
        
        .. code-block:: c
                :linenos:
                :emphasize-lines: 1

                $ kldunload -v ./mutex_module.ko
		Unloading mutex_module.ko, id=8



.. _FreebsdDeviceDriver_basic_fdd_mutex_10:
 
.. tab-set::

    .. tab-item:: Check if the module is unloaded successfully 

        * Run kldstat command to check the loaded modules
        
        .. code-block:: c
                :linenos:
                :emphasize-lines: 1
                
                $ kldstat
                Id Refs Address                Size Name
                 1   27 0xffffffff80200000  1f6c698 kernel
                 2    1 0xffffffff8216d000   772c70 zfs.ko
                 3    1 0xffffffff828e1000     7850 cryptodev.ko
                 4    1 0xffffffff83218000     3220 intpm.ko
                 5    1 0xffffffff8321c000     2178 smbus.ko
                 6    1 0xffffffff8321f000     3360 uhid.ko
                 7    1 0xffffffff83223000     3360 wmt.ko



.. _FreebsdDeviceDriver_basic_fdd_mutex_11:

.. tab-set::

    .. tab-item:: Check what happened on module unload

        * Run dmesg command to check the kernel logs
        
        .. code-block:: c
                :linenos:
                :emphasize-lines: 1
                
                $ dmesg
		Module loaded
		Count = 0
		Count = 1
		Module unloaded