<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jul 16, 2014 at 8:49 PM, Chetan Nanda <span dir="ltr"><<a href="mailto:chetannanda@gmail.com" target="_blank">chetannanda@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div class="h5">On Wed, Jul 16, 2014 at 6:39 PM, John de la Garza <span dir="ltr"><<a href="mailto:john@jjdev.com" target="_blank">john@jjdev.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>On Wed, Jul 16, 2014 at 04:00:18PM +0530, Chetan Nanda wrote:<br>
> A depends on B, so B is automatically loaded when A is loaded.<br>
> B module is also directly being used by the user side code via misc<br>
> interface.<br>
</div>>.<br>
<div>> Now when I am unloading module A, via "modprobe -r A" it is also unloading<br>
> the module B which is being used by the application and resulting in the<br>
> kernel crash.<br>
<br>
</div>You said that A depends on B, right? Why do you have A dependng on B?<br>
If it A needs to have B then it makes sense that you can not remove A while<br>
B is in use. If A doesn't need B, why not remove the dependency.</blockquote></div></div></div></div></div></blockquote><div> </div><div>A is calling few APIs defined by B. </div><div><br></div><div>But why when user space application is already using module B. (it has already open its device fd) kernel allows to remove it.</div>
<div><br></div><div>I tried with doing try_module_get() in the module's open function, it prevent module B unloading but cause thread doing modprobe -r to hang</div><div>Is there any other way to mark module as busy when being used by user application?</div>
</div><br></div></div>