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Commit 83011b6c authored by Tim Sell's avatar Tim Sell Committed by Greg Kroah-Hartman
Browse files

staging: unisys: visorinput: remove unnecessary locking 



Locking in the _interrupt() function is NOT necessary so long as we ensure
that interrupts have been stopped whenever we need to pause or resume the
device, which we now do.

While a device is paused, we ensure that interrupts stay disabled, i.e.
that the _interrupt() function will NOT be called, yet remember the desired
state in devdata->interrupts_enabled if open() or close() are called are
called while the device is paused.  Then when the device is resumed, we
restore the actual state of interrupts (i.e., whether _interrupt() is going
to be called or not) to the desired state in devdata->interrupts_enabled.

Signed-off-by: default avatarTim Sell <Timothy.Sell@unisys.com>
Signed-off-by: default avatarDavid Kershner <david.kershner@unisys.com>
Acked-By: default avatarNeil Horman <nhorman@tuxdriver.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c3d4a970

drivers/staging/unisys/visorinput/visorinput.c

+47 −10
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ struct visorinput_devdata { 
	struct rw_semaphore lock_visor_dev; /* lock for dev */

	struct input_dev *visorinput_dev;

	bool paused;

	bool interrupts_enabled;

	unsigned int keycode_table_bytes; /* size of following array */

	/* for keyboard devices: visorkbd_keycode[] + visorkbd_ext_keycode[] */

	unsigned char keycode_table[0];
@@ -228,7 +229,21 @@ static int visorinput_open(struct input_dev *visorinput_dev) 
		return -EINVAL;

	}

	dev_dbg(&visorinput_dev->dev, "%s opened\n", __func__);



	/*

	 * If we're not paused, really enable interrupts.

	 * Regardless of whether we are paused, set a flag indicating

	 * interrupts should be enabled so when we resume, interrupts

	 * will really be enabled.

	 */

	down_write(&devdata->lock_visor_dev);

	devdata->interrupts_enabled = true;

	if (devdata->paused)

		goto out_unlock;

	visorbus_enable_channel_interrupts(devdata->dev);



out_unlock:

	up_write(&devdata->lock_visor_dev);

	return 0;

}
@@ -243,7 +258,22 @@ static void visorinput_close(struct input_dev *visorinput_dev) 
		return;

	}

	dev_dbg(&visorinput_dev->dev, "%s closed\n", __func__);



	/*

	 * If we're not paused, really disable interrupts.

	 * Regardless of whether we are paused, set a flag indicating

	 * interrupts should be disabled so when we resume we will

	 * not re-enable them.

	 */



	down_write(&devdata->lock_visor_dev);

	devdata->interrupts_enabled = false;

	if (devdata->paused)

		goto out_unlock;

	visorbus_disable_channel_interrupts(devdata->dev);



out_unlock:

	up_write(&devdata->lock_visor_dev);

}



/*
@@ -438,10 +468,8 @@ visorinput_remove(struct visor_device *dev) 
	 * in visorinput_channel_interrupt()

	 */



	down_write(&devdata->lock_visor_dev);

	dev_set_drvdata(&dev->device, NULL);

	unregister_client_input(devdata->visorinput_dev);

	up_write(&devdata->lock_visor_dev);

	kfree(devdata);

}
@@ -529,13 +557,7 @@ visorinput_channel_interrupt(struct visor_device *dev) 
	if (!devdata)

		return;



	down_write(&devdata->lock_visor_dev);

	if (devdata->paused) /* don't touch device/channel when paused */

		goto out_locked;



	visorinput_dev = devdata->visorinput_dev;

	if (!visorinput_dev)

		goto out_locked;



	while (visorchannel_signalremove(dev->visorchannel, 0, &r)) {

		scancode = r.activity.arg1;
@@ -611,8 +633,6 @@ visorinput_channel_interrupt(struct visor_device *dev) 
			break;

		}

	}

out_locked:

	up_write(&devdata->lock_visor_dev);

}



static int
@@ -632,6 +652,14 @@ visorinput_pause(struct visor_device *dev, 
		rc = -EBUSY;

		goto out_locked;

	}

	if (devdata->interrupts_enabled)

		visorbus_disable_channel_interrupts(dev);



	/*

	 * due to above, at this time no thread of execution will be

	 * in visorinput_channel_interrupt()

	 */



	devdata->paused = true;

	complete_func(dev, 0);

	rc = 0;
@@ -659,6 +687,15 @@ visorinput_resume(struct visor_device *dev, 
	}

	devdata->paused = false;

	complete_func(dev, 0);



	/*

	 * Re-establish calls to visorinput_channel_interrupt() if that is

	 * the desired state that we've kept track of in interrupts_enabled

	 * while the device was paused.

	 */

	if (devdata->interrupts_enabled)

		visorbus_enable_channel_interrupts(dev);



	rc = 0;

out_locked:

	up_write(&devdata->lock_visor_dev);