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authorSudip Mukherjee <sudipm.mukherjee@gmail.com>2015-06-12 15:20:20 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-06-12 16:58:33 -0700
commit50566ac87065b9ade71aef5e69d23e06a0664db9 (patch)
treedd3adf294fc1eff1fcbbeee93e4a65e68ea03f39 /drivers/parport
parent0c6d5c89a112620d2166b8d042d3d69bb42b626c (diff)
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: Sudip Mukherjee <sudip@vectorindia.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/parport')
-rw-r--r--drivers/parport/share.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/parport/share.c b/drivers/parport/share.c
index 697c6d7bf0fe..8067f54ce050 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;