From: Tim Sell <Timothy.Sell@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: David Kershner <david.kershner@xxxxxxxxxx>
---
drivers/staging/unisys/visorinput/visorinput.c | 57 +++++++++++++++++++++-----
1 file changed, 47 insertions(+), 10 deletions(-)
diff --git a/drivers/staging/unisys/visorinput/visorinput.c b/drivers/staging/unisys/visorinput/visorinput.c
index 12a3570..9c00710 100644
--- a/drivers/staging/unisys/visorinput/visorinput.c
+++ b/drivers/staging/unisys/visorinput/visorinput.c
@@ -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);
--
1.9.1
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