[PATCH] staging: dgnc: Remove useless and deadly judgment

[navych@126.com (Navy Cheng)]

On Mon, Feb 29, 2016 at 02:58:16AM -0500, Valdis.Kletnieks at vt.edu wrote:
> On Mon, 29 Feb 2016 14:41:34 +0800, Navy Cheng said:
> > pci_unregister_driver() should be used once dgnc module exit. It has
> > nothing to do with dgnc_NumBoards. Remove the judgment of dgnc_NumBoards to
> > avoid pci_unregister_driver() is not used when dgnc_NumBoards is 0.
> 
> > -	if (dgnc_NumBoards)
> > -		pci_unregister_driver(&dgnc_driver);
> > +	pci_unregister_driver(&dgnc_driver);
> 
> Does pci_unregister_driver do the right thing if there are 0 boards
> in the system?

I have no dgnc device in my laptop. After *insmod* and *rmmod* dgnc module,
I can re-insmod dgnc successfully. If dgnc is *rmmod*, the dgnc-file in /sys
will disappear.

> If this logic is wrong, shouldn't there also be a patch fixing the
> following in dgnc_init_module()?

Yes, I thought dgnc_init_module should be fixed. But I'm not familiar with
how to submitting patchset. I decide to fix dgnc_cleanup_module() first.

>         /*
>          * Find and configure all the cards
>          */
>         rc = pci_register_driver(&dgnc_driver);
> 
>         /*
>          * If something went wrong in the scan, bail out of driver.
>          */
>         if (rc < 0) {
>                 /* Only unregister if it was actually registered. */
>                 if (dgnc_NumBoards)
>                         pci_unregister_driver(&dgnc_driver);
>                 else
>                         pr_warn("WARNING: dgnc driver load failed.  No Digi Neo or Classic boards found.\n");
> 
>                 dgnc_cleanup_module();
> 
> While I'm at it, the entire NumBoards counting seems to be wonky - it looks
> like a *lot* of off-by-one errors.  Looks like the programmer(s) weren't sure
> if they wanted to use that as a zero-based or one-based counter/index.
> 

Maybe we can fix the *init* and *exit* like this:

    static int __init dgnc_init_module(void)
    {
        int rc;

        rc = dgnc_start();
	if (rc < 0)
            goto err1;

        rc = pci_register_driver(&dgnc_driver)
	if (rc <0) {
	    goto err1;
	    pr_warn("....");
	}

        rc = dgnc_create_driver_sysfiles(&dgnc_driver);

	if (rc = 0)
            goto err2;

	return rc;
	 
    err2:
        pci_unregister_driver(&dgnc_driver);
    err1:
        dgnc_end();

	return rc;
    }
    
    static void dgnc_cleanup_module(void)
    {
        int i;

	dgnc_remove_driver_sysfiles(&dgnc_driver);

	for (i = 0; i < dgnc_NumBoards; ++i) {
	    dgnc_remove_ports_sysfiles(dgnc_Board[i]);
            dgnc_tty_uninit(dgnc_Board[i]);
	    dgnc_cleanup_board(dgnc_Board[i]);
	}

        pci_unregister_driver(&dgnc_driver);

     	dgnc_end();
    }