From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755488AbbFLJuh (ORCPT ); Fri, 12 Jun 2015 05:50:37 -0400 Received: from mail-pd0-f169.google.com ([209.85.192.169]:35629 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277AbbFLJua (ORCPT ); Fri, 12 Jun 2015 05:50:30 -0400 From: Sudip Mukherjee To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, Sudip Mukherjee Subject: [PATCH] parport: check exclusive access before register Date: Fri, 12 Jun 2015 15:20:20 +0530 Message-Id: <1434102620-2564-1-git-send-email-sudipm.mukherjee@gmail.com> X-Mailer: git-send-email 1.8.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- Hi Greg, One doubt - if anyone sends any patch regarding parport, it will be addressed to me. so do i need to forward it to you? drivers/parport/share.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/drivers/parport/share.c b/drivers/parport/share.c index 697c6d7..8067f54 100644 --- a/drivers/parport/share.c +++ b/drivers/parport/share.c @@ -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; -- 1.8.1.2