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<div class="section" id="sanity">
<h1>Sanity<a class="headerlink" href="#sanity" title="Permalink to this headline"></a></h1>
<p>The Sanity task is a software watchdog task, which runs periodically to
check system state, and ensure that everything is still operating
properly.</p>
<p>In a typical system design, there are multiple stages of watchdog:</p>
<ul class="simple">
<li><p>Internal Watchdog</p></li>
<li><p>External Watchdog</p></li>
<li><p>Sanity Watchdog</p></li>
</ul>
<p>The <em>Internal Watchdog</em> is typically an MCU watchdog, which is tickled
in the core of the OS. The internal watchdog is tickled frequently, and
is meant to be an indicator the OS is running.</p>
<p>The <em>External Watchdog</em> is a watchdog that’s typically run slower. The
purpose of an external watchdog is to provide the system with a hard
reset when it has lost its mind.</p>
<p>The <em>Sanity Watchdog</em> is the least frequently run watchdog, and is meant
as an application watchdog.</p>
<p>This document is about the operation of the Mynewt Sanity Watchdog.</p>
<div class="section" id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this headline"></a></h2>
</div>
<div class="section" id="sanity-task">
<h2>Sanity Task<a class="headerlink" href="#sanity-task" title="Permalink to this headline"></a></h2>
<p>Mynewt OS uses the OS Idle task to check sanity. The <code class="xref c c-macro docutils literal notranslate"><span class="pre">SANITY_INTERVAL</span></code>
syscfg setting specifies the interval in seconds to perform the sanity
checks.</p>
<p>By default, every operating system task provides the frequency it will
check in with the sanity task, with the <code class="docutils literal notranslate"><span class="pre">sanity_itvl</span></code> parameter in the
c:func:<cite>os_task_init()</cite> function:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="kt">int</span><span class="w"> </span><span class="nf">os_task_init</span><span class="p">(</span><span class="k">struct</span><span class="w"> </span><span class="nc">os_task</span><span class="w"> </span><span class="o">*</span><span class="n">t</span><span class="p">,</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="o">*</span><span class="n">name</span><span class="p">,</span><span class="w"> </span><span class="n">os_task_func_t</span><span class="w"> </span><span class="n">func</span><span class="p">,</span>
<span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="o">*</span><span class="n">arg</span><span class="p">,</span><span class="w"> </span><span class="kt">uint8_t</span><span class="w"> </span><span class="n">prio</span><span class="p">,</span><span class="w"> </span><span class="n">os_time_t</span><span class="w"> </span><span class="n">sanity_itvl</span><span class="p">,</span><span class="w"> </span><span class="n">os_stack_t</span><span class="w"> </span><span class="o">*</span><span class="n">bottom</span><span class="p">,</span>
<span class="w"> </span><span class="kt">uint16_t</span><span class="w"> </span><span class="n">stack_size</span><span class="p">);</span>
</pre></div>
</div>
<p>c:var:<cite>sanity_itvl</cite> is the time in OS time ticks that the task being created
must register in with the sanity task.</p>
</div>
<div class="section" id="checking-in-with-sanity-task">
<h2>Checking in with Sanity Task<a class="headerlink" href="#checking-in-with-sanity-task" title="Permalink to this headline"></a></h2>
<p>The task must then register in with the sanity task every
<code class="docutils literal notranslate"><span class="pre">sanity_itvl</span></code> seconds. In order to do that, the task should call the
<a class="reference internal" href="#c.os_sanity_task_checkin" title="os_sanity_task_checkin"><code class="xref c c-func docutils literal notranslate"><span class="pre">os_sanity_task_checkin()</span></code></a> function, which will reset the sanity check
associated with this task. Here is an example of a task that uses a
callout to checkin with the sanity task every 50 seconds:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#define TASK1_SANITY_CHECKIN_ITVL (50 * OS_TICKS_PER_SEC)</span>
<span class="k">struct</span><span class="w"> </span><span class="nc">os_eventq</span><span class="w"> </span><span class="n">task1_evq</span><span class="p">;</span>
<span class="k">static</span><span class="w"> </span><span class="kt">void</span>
<span class="nf">task1</span><span class="p">(</span><span class="kt">void</span><span class="w"> </span><span class="o">*</span><span class="n">arg</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">os_task</span><span class="w"> </span><span class="o">*</span><span class="n">t</span><span class="p">;</span>
<span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">os_event</span><span class="w"> </span><span class="o">*</span><span class="n">ev</span><span class="p">;</span>
<span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">os_callout</span><span class="w"> </span><span class="n">c</span><span class="p">;</span>
<span class="w"> </span><span class="cm">/* Get current OS task */</span>
<span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">os_sched_get_current_task</span><span class="p">();</span>
<span class="w"> </span><span class="cm">/* Initialize the event queue. */</span>
<span class="w"> </span><span class="n">os_eventq_init</span><span class="p">(</span><span class="o">&amp;</span><span class="n">task1_evq</span><span class="p">);</span>
<span class="w"> </span><span class="cm">/* Initialize the callout */</span>
<span class="w"> </span><span class="n">os_callout_init</span><span class="p">(</span><span class="o">&amp;</span><span class="n">c</span><span class="p">,</span><span class="w"> </span><span class="o">&amp;</span><span class="n">task1_evq</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">);</span>
<span class="w"> </span><span class="cm">/* reset the callout to checkin with the sanity task</span>
<span class="cm"> * in 50 seconds to kick off timing.</span>
<span class="cm"> */</span>
<span class="w"> </span><span class="n">os_callout_reset</span><span class="p">(</span><span class="o">&amp;</span><span class="n">c</span><span class="p">,</span><span class="w"> </span><span class="n">TASK1_SANITY_CHECKIN_ITVL</span><span class="p">);</span>
<span class="w"> </span><span class="k">while</span><span class="w"> </span><span class="p">(</span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">ev</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">os_eventq_get</span><span class="p">(</span><span class="o">&amp;</span><span class="n">task1_evq</span><span class="p">);</span>
<span class="w"> </span><span class="cm">/* The sanity timer has reset */</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">ev</span><span class="o">-&gt;</span><span class="n">ev_arg</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="o">&amp;</span><span class="n">c</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">os_sanity_task_checkin</span><span class="p">(</span><span class="n">t</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="cm">/* not expecting any other events */</span>
<span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="mi">0</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="cm">/* Should never reach */</span>
<span class="w"> </span><span class="n">assert</span><span class="p">(</span><span class="mi">0</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="registering-a-custom-sanity-check">
<h2>Registering a Custom Sanity Check<a class="headerlink" href="#registering-a-custom-sanity-check" title="Permalink to this headline"></a></h2>
<p>If a particular task wants to further hook into the sanity framework to
perform other checks during the sanity task’s operation, it can do so by
registering a <code class="xref c c-type docutils literal notranslate"><span class="pre">struct</span> <span class="pre">os_sanity_check</span></code> using the
<a class="reference internal" href="#c.os_sanity_check_register" title="os_sanity_check_register"><code class="xref c c-func docutils literal notranslate"><span class="pre">os_sanity_check_register()</span></code></a> function.</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">static</span><span class="w"> </span><span class="kt">int</span>
<span class="nf">mymodule_perform_sanity_check</span><span class="p">(</span><span class="k">struct</span><span class="w"> </span><span class="nc">os_sanity_check</span><span class="w"> </span><span class="o">*</span><span class="n">sc</span><span class="p">,</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="o">*</span><span class="n">arg</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="cm">/* Perform your checking here. In this case, we check if there</span>
<span class="cm"> * are available buffers in mymodule, and return 0 (all good)</span>
<span class="cm"> * if true, and -1 (error) if not.</span>
<span class="cm"> */</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">mymodule_has_buffers</span><span class="p">())</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="p">(</span><span class="mi">0</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="p">(</span><span class="mi">-1</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
<span class="k">static</span><span class="w"> </span><span class="kt">int</span>
<span class="nf">mymodule_register_sanity_check</span><span class="p">(</span><span class="kt">void</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">os_sanity_check</span><span class="w"> </span><span class="n">sc</span><span class="p">;</span>
<span class="w"> </span><span class="n">os_sanity_check_init</span><span class="p">(</span><span class="o">&amp;</span><span class="n">sc</span><span class="p">);</span>
<span class="w"> </span><span class="cm">/* Only assert() if mymodule_perform_sanity_check() fails 50</span>
<span class="cm"> * times. SANITY_TASK_INTERVAL is defined by the user, and</span>
<span class="cm"> * is the frequency at which the sanity_task runs in seconds.</span>
<span class="cm"> */</span>
<span class="w"> </span><span class="n">OS_SANITY_CHECK_SETFUNC</span><span class="p">(</span><span class="o">&amp;</span><span class="n">sc</span><span class="p">,</span><span class="w"> </span><span class="n">mymodule_perform_sanity_check</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">,</span>
<span class="w"> </span><span class="mi">50</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="n">SANITY_TASK_INTERVAL</span><span class="p">);</span>
<span class="w"> </span><span class="n">rc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">os_sanity_check_register</span><span class="p">(</span><span class="o">&amp;</span><span class="n">sc</span><span class="p">);</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">rc</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">goto</span><span class="w"> </span><span class="n">err</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="p">(</span><span class="mi">0</span><span class="p">);</span>
<span class="nl">err</span><span class="p">:</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="p">(</span><span class="n">rc</span><span class="p">);</span>
<span class="p">}</span>
</pre></div>
</div>
<p>In the above example, every time the custom sanity check
<code class="docutils literal notranslate"><span class="pre">mymodule_perform_sanity_check</span></code> returns successfully (0), the sanity
check is reset. In the c:macro:<cite>OS_SANITY_CHECK_SETFUNC</cite> macro, the sanity
checkin interval is specified as 50 * <code class="xref c c-macro docutils literal notranslate"><span class="pre">SANITY_TASK_INTERVAL</span></code> (which is
the interval at which the sanity task runs.) This means that the
<code class="docutils literal notranslate"><span class="pre">mymodule_perform_sanity_check()</span></code> function needs to fail 50 times
consecutively before the sanity task will crash the system.</p>
<p><strong>TIP:</strong> When checking things like memory buffers, which can be
temporarily be exhausted, it’s a good idea to have the sanity check fail
multiple consecutive times before crashing the system. This will avoid
crashing for temporary failures.</p>
</div>
<div class="section" id="api">
<h2>API<a class="headerlink" href="#api" title="Permalink to this headline"></a></h2>
<dl class="c type">
<dt id="c.os_sanity_check_func_t">
<span class="target" id="group___o_s_sanity_1ga354458457ad42d0bab3d8d08de482fc9"></span><em class="property"><span class="pre">typedef</span> </em><span class="pre">int</span> <span class="pre">(</span><span class="pre">*</span><code class="sig-name descname"><span class="pre">os_sanity_check_func_t</span></code><span class="pre">)</span><span class="sig-paren">(</span><em class="property"><span class="pre">struct</span></em> <a class="reference internal" href="#c.os_sanity_check" title="os_sanity_check"><span class="pre">os_sanity_check</span></a><span class="pre">*</span>, <span class="pre">void</span><span class="pre">*</span><span class="sig-paren">)</span><a class="headerlink" href="#c.os_sanity_check_func_t" title="Permalink to this definition"></a><br /></dt>
<dd></dd></dl>
<dl class="c function">
<dt id="c.os_sanity_task_checkin">
<span class="target" id="group___o_s_sanity_1ga048cde3537cb470594fc2528201572ba"></span><span class="pre">int</span> <code class="sig-name descname"><span class="pre">os_sanity_task_checkin</span></code><span class="sig-paren">(</span><em class="property"><span class="pre">struct</span></em> <a class="reference internal" href="../task/task.html#c.os_task" title="os_task"><span class="pre">os_task</span></a><span class="pre">*</span><span class="sig-paren">)</span><a class="headerlink" href="#c.os_sanity_task_checkin" title="Permalink to this definition"></a><br /></dt>
<dd><p>Provide a “task checkin” for the sanity task. </p>
<p><dl class="simple">
<dt><strong>Return</strong></dt><dd><p>0 on success, error code on failure </p>
</dd>
<dt><strong>Parameters</strong></dt><dd><ul class="breatheparameterlist simple">
<li><p><code class="docutils literal notranslate"><span class="pre">t</span></code>: The task to check in</p></li>
</ul>
</dd>
</dl>
</p>
</dd></dl>
<dl class="c function">
<dt id="c.os_sanity_check_init">
<span class="target" id="group___o_s_sanity_1ga34eb185813afec28e2d61059e2fdd064"></span><span class="pre">int</span> <code class="sig-name descname"><span class="pre">os_sanity_check_init</span></code><span class="sig-paren">(</span><em class="property"><span class="pre">struct</span></em> <a class="reference internal" href="#c.os_sanity_check" title="os_sanity_check"><span class="pre">os_sanity_check</span></a><span class="pre">*</span><span class="sig-paren">)</span><a class="headerlink" href="#c.os_sanity_check_init" title="Permalink to this definition"></a><br /></dt>
<dd><p>Initialize a sanity check. </p>
<p><dl class="simple">
<dt><strong>Return</strong></dt><dd><p>0 on success, error code on failure. </p>
</dd>
<dt><strong>Parameters</strong></dt><dd><ul class="breatheparameterlist simple">
<li><p><code class="docutils literal notranslate"><span class="pre">sc</span></code>: The sanity check to initialize</p></li>
</ul>
</dd>
</dl>
</p>
</dd></dl>
<dl class="c function">
<dt id="c.os_sanity_check_register">
<span class="target" id="group___o_s_sanity_1ga2c5ad3969bf12870a0adfa7b9a8a8611"></span><span class="pre">int</span> <code class="sig-name descname"><span class="pre">os_sanity_check_register</span></code><span class="sig-paren">(</span><em class="property"><span class="pre">struct</span></em> <a class="reference internal" href="#c.os_sanity_check" title="os_sanity_check"><span class="pre">os_sanity_check</span></a><span class="pre">*</span><span class="sig-paren">)</span><a class="headerlink" href="#c.os_sanity_check_register" title="Permalink to this definition"></a><br /></dt>
<dd><p>Register a sanity check. </p>
<p><dl class="simple">
<dt><strong>Return</strong></dt><dd><p>0 on success, error code on failure </p>
</dd>
<dt><strong>Parameters</strong></dt><dd><ul class="breatheparameterlist simple">
<li><p><code class="docutils literal notranslate"><span class="pre">sc</span></code>: The sanity check to register</p></li>
</ul>
</dd>
</dl>
</p>
</dd></dl>
<dl class="c function">
<dt id="c.os_sanity_check_reset">
<span class="target" id="group___o_s_sanity_1ga92ea98a26001d84aee06d600c62b7140"></span><span class="pre">int</span> <code class="sig-name descname"><span class="pre">os_sanity_check_reset</span></code><span class="sig-paren">(</span><em class="property"><span class="pre">struct</span></em> <a class="reference internal" href="#c.os_sanity_check" title="os_sanity_check"><span class="pre">os_sanity_check</span></a><span class="pre">*</span><span class="sig-paren">)</span><a class="headerlink" href="#c.os_sanity_check_reset" title="Permalink to this definition"></a><br /></dt>
<dd><p>Reset the os sanity check, so that it doesn’t trip up the sanity timer. </p>
<p><dl class="simple">
<dt><strong>Return</strong></dt><dd><p>0 on success, error code on failure </p>
</dd>
<dt><strong>Parameters</strong></dt><dd><ul class="breatheparameterlist simple">
<li><p><code class="docutils literal notranslate"><span class="pre">sc</span></code>: The sanity check to reset</p></li>
</ul>
</dd>
</dl>
</p>
</dd></dl>
<dl class="c macro">
<dt id="c.OS_SANITY_CHECK_SETFUNC">
<span class="target" id="group___o_s_sanity_1ga53501a44869b9cda63c92f031d8a46c5"></span><code class="sig-name descname"><span class="pre">OS_SANITY_CHECK_SETFUNC</span></code><span class="sig-paren">(</span><em><span class="pre">__sc</span></em>, <em><span class="pre">__f</span></em>, <em><span class="pre">__arg</span></em>, <em><span class="pre">__itvl</span></em><span class="sig-paren">)</span><a class="headerlink" href="#c.OS_SANITY_CHECK_SETFUNC" title="Permalink to this definition"></a><br /></dt>
<dd></dd></dl>
<dl class="c struct">
<dt id="c.os_sanity_check">
<span class="target" id="structos__sanity__check"></span><em class="property"><span class="pre">struct</span> </em><code class="sig-name descname"><span class="pre">os_sanity_check</span></code><a class="headerlink" href="#c.os_sanity_check" title="Permalink to this definition"></a><br /></dt>
<dd><em>#include &lt;os_sanity.h&gt;</em><div class="breathe-sectiondef docutils container">
<p class="breathe-sectiondef-title rubric" id="breathe-section-title-public-members">Public Members</p>
<dl class="c var">
<dt id="c.os_sanity_check.sc_checkin_last">
<span class="target" id="structos__sanity__check_1a7701ac67d9e7ba081cef9a6540a35003"></span><a class="reference internal" href="../time/os_time.html#c.os_time_t" title="os_time_t"><span class="pre">os_time_t</span></a> <code class="sig-name descname"><span class="pre">sc_checkin_last</span></code><a class="headerlink" href="#c.os_sanity_check.sc_checkin_last" title="Permalink to this definition"></a><br /></dt>
<dd><p>Time this check last ran successfully. </p>
</dd></dl>
<dl class="c var">
<dt id="c.os_sanity_check.sc_checkin_itvl">
<span class="target" id="structos__sanity__check_1ad9b79d0e7c0dcc9fcbfe57d2b7d43c53"></span><a class="reference internal" href="../time/os_time.html#c.os_time_t" title="os_time_t"><span class="pre">os_time_t</span></a> <code class="sig-name descname"><span class="pre">sc_checkin_itvl</span></code><a class="headerlink" href="#c.os_sanity_check.sc_checkin_itvl" title="Permalink to this definition"></a><br /></dt>
<dd><p>Interval this task should check in at. </p>
</dd></dl>
<dl class="c var">
<dt id="c.os_sanity_check.sc_func">
<span class="target" id="structos__sanity__check_1ab5be2cbf4891bc9f42f25b7f4cfb9b45"></span><a class="reference internal" href="#c.os_sanity_check_func_t" title="os_sanity_check_func_t"><span class="pre">os_sanity_check_func_t</span></a> <code class="sig-name descname"><span class="pre">sc_func</span></code><a class="headerlink" href="#c.os_sanity_check.sc_func" title="Permalink to this definition"></a><br /></dt>
<dd><p>Sanity check to run. </p>
</dd></dl>
<dl class="c var">
<dt id="c.os_sanity_check.sc_arg">
<span class="target" id="structos__sanity__check_1a5b22c20409427a0561fb2418a251706a"></span><span class="pre">void</span> <span class="pre">*</span><code class="sig-name descname"><span class="pre">sc_arg</span></code><a class="headerlink" href="#c.os_sanity_check.sc_arg" title="Permalink to this definition"></a><br /></dt>
<dd><p>Argument to pass to sanity check. </p>
</dd></dl>
</div>
</dd></dl>
</div>
</div>
</div>
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