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, 15 deletions

diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
index 963ac197c253..b77d700a3f0e 100644
--- a/drivers/hwtracing/coresight/coresight-replicator.c
+++ b/drivers/hwtracing/coresight/coresight-replicator.c
@@ -127,20 +127,6 @@ out_disable_pm:
 	return ret;
 }
 
-static int replicator_remove(struct platform_device *pdev)
-{
-	struct replicator_drvdata *drvdata = platform_get_drvdata(pdev);
-
-	coresight_unregister(drvdata->csdev);
-	pm_runtime_get_sync(&pdev->dev);
-	if (!IS_ERR(drvdata->atclk))
-		clk_disable_unprepare(drvdata->atclk);
-	pm_runtime_put_noidle(&pdev->dev);
-	pm_runtime_disable(&pdev->dev);
-
-	return 0;
-}
-
 #ifdef CONFIG_PM
 static int replicator_runtime_suspend(struct device *dev)
 {
@@ -175,11 +161,11 @@ static const struct of_device_id replicator_match[] = {
 
 static struct platform_driver replicator_driver = {
 	.probe          = replicator_probe,
-	.remove         = replicator_remove,
 	.driver         = {
 		.name   = "coresight-replicator",
 		.of_match_table = replicator_match,
 		.pm	= &replicator_dev_pm_ops,
+		.suppress_bind_attrs = true,
 	},
 };