parport: check exclusive access before register (50566ac8) · Commits · 戴 / test

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:

Sudip Mukherjee <sudip@vectorindia.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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;

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