Dear All,<br><div class="gmail_quote"><p class="MsoNormal"><br></p><p class="MsoNormal">I was trying the following and had a doubt.</p><p class="MsoNormal"><br></p><p class="MsoNormal">From my kernel module I want to
iterate over task list and do some sleepy operation for all the process for
which my task-&gt;flag is set .I know by holding
read_lock(tasklist_lock)/rcu_read_lock I should not be performing any sleepy operation. So I have coded like below :</p><p class="MsoNormal"></p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">1.  Take the read lock</p>

<p class="MsoNormal">2.  Iterate over
task (for_each_process)</p>

<p class="MsoNormal">3.  If my flag is set I unlock
the tasklist_lock and get_task_struct</p>

<p class="MsoNormal">4.  Perform the sleepy operation</p>

<p class="MsoNormal">5.  Then put_task_struct</p>

<p class="MsoNormal">6.  Again take
read_lock(&amp;tasklist_lock);</p>

<p class="MsoNormal">7.  Loop continues  </p>

<p class="MsoNormal"> </p><p class="MsoNormal">The code snippet is as shown below :</p><p class="MsoNormal"><br></p>

<p class="MsoNormal">read_lock(&amp;tasklist_lock);</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal"> for_each_process(c) {</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">  if (c-&gt;my_flag) {</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">          read_unlock(&amp;tasklist_lock);</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">           get_task_struct(c);</p><p class="MsoNormal"><br></p>

<p class="MsoNormal">                    ...</p><p class="MsoNormal"><br></p><p class="MsoNormal"></p>

<p class="MsoNormal">                    perform_sleepy_operation();</p><p class="MsoNormal"><br></p>

<p class="MsoNormal">                     ...</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">            put_task_struct(c);</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">             read_lock(&amp;tasklist_lock);</p>

<p class="MsoNormal">                 }</p><p class="MsoNormal"></p>

<p class="MsoNormal">  </p>

<p class="MsoNormal">         }</p>

<p class="MsoNormal"> </p>

<p class="MsoNormal">Please let me know if this approach is correct.</p><p class="MsoNormal"><br></p><p class="MsoNormal">Thanks and Regards,</p><p class="MsoNormal">Pranami</p>
</div><br>