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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: Tim Sell <Timothy.Sell@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Acked-By: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tim Sell 2016-06-10 21:48:07 -04:00 committed by Greg Kroah-Hartman
parent c3d4a97033
commit 83011b6cbe
1 changed files with 47 additions and 10 deletions
drivers/staging/unisys/visorinput
visorinput.c

57
drivers/staging/unisys/visorinput/visorinput.c
View File

@ -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);