coresight: removing bind/unbind options from sysfs

The coresight drivers have absolutely no control over bind and unbind
operations triggered from sysfs. The operations simply can't be
cancelled or denied event when one or several tracing sessions are
under way.  Since the memory associated to individual device is
invariably freed, the end result is a kernel crash when the path from
source to sink is travelled again as demonstrated here[1].

One solution could be to keep track of all the path (i.e tracing
session) that get created and iterate through the elements of those path
looking for the coresight device that is being removed.  This proposition
doesn't scale well since there is no upper bound on the amount of
concurrent trace session that can be created.

With the above in mind, this patch prevent devices from being unbounded
from their driver by using the driver->suppress_bind_attr option.  That way
trace sessions can be managed without fearing to loose devices.

Since device can't be removed anymore the xyz_remove() functions found in
each driver is also removed.

[1]. http://www.spinics.net/lists/arm-kernel/msg474952.html

Reported-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 9 deletions

diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
index 2e36bde7fcb4..25e8ea140a09 100644
--- a/drivers/hwtracing/coresight/coresight-funnel.c
+++ b/drivers/hwtracing/coresight/coresight-funnel.c
@@ -226,14 +226,6 @@ static int funnel_probe(struct amba_device *adev, const struct amba_id *id)
 	return 0;
 }
 
-static int funnel_remove(struct amba_device *adev)
-{
-	struct funnel_drvdata *drvdata = amba_get_drvdata(adev);
-
-	coresight_unregister(drvdata->csdev);
-	return 0;
-}
-
 #ifdef CONFIG_PM
 static int funnel_runtime_suspend(struct device *dev)
 {
@@ -273,9 +265,9 @@ static struct amba_driver funnel_driver = {
 		.name	= "coresight-funnel",
 		.owner	= THIS_MODULE,
 		.pm	= &funnel_dev_pm_ops,
+		.suppress_bind_attrs = true,
 	},
 	.probe		= funnel_probe,
-	.remove		= funnel_remove,
 	.id_table	= funnel_ids,
 };