[openib-general][PATCH][kdapl]: inc/dec module ref count

[Muli Ben-Yehuda]

On Thu, Jul 28, 2005 at 10:14:15AM +0300, Guy German wrote:

> [kdapl]: increments the module ref count on ia_open, thus making
> sure the kdapl_ib module would not be rmmod-ed while in use
> 
> Signed-off-by: Guy German <guyg at voltaire.com>
> 
> Index: infiniband/ulp/kdapl/ib/dapl_ia.c
> ===================================================================
> --- infiniband/ulp/kdapl/ib/dapl_ia.c	(revision 2914)
> +++ infiniband/ulp/kdapl/ib/dapl_ia.c	(working copy)
> @@ -649,6 +649,7 @@ int dapl_ia_open(const char *name, int a
>  	status = 0;
>  	*ia_ptr = (struct dat_ia *)ia;
>  	*async_evd = (struct dat_evd *)evd;
> +	try_module_get(THIS_MODULE);

This does not look right. First, try_module_get() may fail. Second,
you're calling it in the context of your module - what happens if
someone tried to remove it while dapl_ia_open() is running and before
the call? 

The right place to do module refcounting is in the caller, not in the
callee. In this case - whereever dapl_ia_open() can be called from.

>  bail:
>  	if (status != 0)
> @@ -679,6 +680,7 @@ int dapl_ia_close(struct dat_ia *ia_ptr,
>  	else
>  		status = -EINVAL;
> 
> +	module_put(THIS_MODULE);

Likewise.

Cheers,
Muli
-- 
Muli Ben-Yehuda
http://www.mulix.org | http://mulix.livejournal.com/