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Commit 50566ac8 authored by Sudip Mukherjee's avatar Sudip Mukherjee Committed by Greg Kroah-Hartman
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parport: check exclusive access before register 



As of now we were starting the registration process and after the device
is registered we were checking if the device can be used by the
parport. Now lets check it first so that we do not need to go through
the registration process only to fail at the end.
The original exclusive access check at the end is still there so that we
do not get any surprises if two different process registers its device
with same parport and with exclusive access at the same time.

Signed-off-by: default avatarSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0c6d5c89

drivers/parport/share.c

+28 −0
Original line number Diff line number Diff line
@@ -708,6 +708,20 @@ parport_register_device(struct parport *port, const char *name, 
		}

	}



	if (flags & PARPORT_DEV_EXCL) {

		if (port->physport->devices) {

			/*

			 * If a device is already registered and this new

			 * device wants exclusive access, then no need to

			 * continue as we can not grant exclusive access to

			 * this device.

			 */

			pr_err("%s: cannot grant exclusive access for device %s\n",

			       port->name, name);

			return NULL;

		}

	}



	/* We up our own module reference count, and that of the port

           on which a device is to be registered, to ensure that

           neither of us gets unloaded while we sleep in (e.g.)
@@ -827,6 +841,20 @@ parport_register_dev_model(struct parport *port, const char *name, 
		}

	}



	if (par_dev_cb->flags & PARPORT_DEV_EXCL) {

		if (port->physport->devices) {

			/*

			 * If a device is already registered and this new

			 * device wants exclusive access, then no need to

			 * continue as we can not grant exclusive access to

			 * this device.

			 */

			pr_err("%s: cannot grant exclusive access for device %s\n",

			       port->name, name);

			return NULL;

		}

	}



	if (!try_module_get(port->ops->owner))

		return NULL;