long story short, i was perusing the kernel source tree, looking for
a random loadable module file to demonstrate the concept of a module
init() routine undoing whatever work it had done in case it runs into
an error, and i chanced across drivers/usb/gadget/dummy_hcd.c, where i
saw at the bottom of the file:
... snip ...
return retval;
err_add_udc:
platform_device_del(the_hcd_pdev);
err_add_hcd:
platform_driver_unregister(&dummy_udc_driver);
err_register_udc_driver:
platform_driver_unregister(&dummy_hcd_driver);
err_register_hcd_driver:
platform_device_put(the_udc_pdev);
err_alloc_udc:
platform_device_put(the_hcd_pdev);
return retval;
}
module_init (init);
static void __exit cleanup (void)
{
platform_device_unregister(the_udc_pdev);
platform_device_unregister(the_hcd_pdev);
platform_driver_unregister(&dummy_udc_driver);
platform_driver_unregister(&dummy_hcd_driver);
}
note how the init() routine backs off on "the_udc_pdev" and
"the_hcd_pdev" objects by calling platform_device_put(), while the
exit() routine uses platform_device_unregister() instead. maybe i
just don't understand enough about what's going on underneath. is
there a reason that those two invocations don't match?
rday
--
========================================================================
Robert P. J. Day Waterloo, Ontario, CANADA
Linux Consulting, Training and Annoying Kernel Pedantry.
Web page: http://crashcourse.ca
Linked In: http://www.linkedin.com/in/rpjday
Twitter: http://twitter.com/rpjday
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