[PATCH] driver core: add test of driver remove calls during probe

From: Rob Herring
Date: Thu Aug 11 2016 - 11:21:08 EST


In recent discussions on ksummit-discuss[1], it was suggested to do a
sequence of probe, remove, probe for testing driver remove paths. This
adds a kconfig option for said test.

[1] https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2016-August/003459.html

Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
drivers/base/Kconfig | 10 ++++++++++
drivers/base/dd.c | 21 +++++++++++++++++++++
2 files changed, 31 insertions(+)

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 98504ec..fdf44ca 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -212,6 +212,16 @@ config DEBUG_DEVRES

If you are unsure about this, Say N here.

+config DEBUG_TEST_DRIVER_REMOVE
+ bool "Test driver remove calls during probe"
+ depends on DEBUG_KERNEL
+ help
+ Say Y here if you want the Driver core to test driver remove functions
+ by calling probe, remove, probe. This tests the remove path without
+ having to unbind the driver or unload the driver module.
+
+ If you are unsure about this, say N here.
+
config SYS_HYPERVISOR
bool
default n
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 16688f5..4910e6d 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -329,6 +329,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
{
int ret = -EPROBE_DEFER;
int local_trigger_count = atomic_read(&deferred_trigger_count);
+ bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE);

if (defer_all_probes) {
/*
@@ -346,6 +347,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
drv->bus->name, __func__, drv->name, dev_name(dev));
WARN_ON(!list_empty(&dev->devres_head));

+re_probe:
dev->driver = drv;

/* If using pinctrl, bind pins now before probing */
@@ -383,6 +385,25 @@ static int really_probe(struct device *dev, struct device_driver *drv)
goto probe_failed;
}

+ if (test_remove) {
+ test_remove = false;
+
+ if (dev->bus && dev->bus->remove)
+ dev->bus->remove(dev);
+ else if (drv->remove)
+ drv->remove(dev);
+
+ devres_release_all(dev);
+ driver_sysfs_remove(dev);
+ dev->driver = NULL;
+ dev_set_drvdata(dev, NULL);
+ if (dev->pm_domain && dev->pm_domain->dismiss)
+ dev->pm_domain->dismiss(dev);
+ pm_runtime_reinit(dev);
+
+ goto re_probe;
+ }
+
pinctrl_init_done(dev);

if (dev->pm_domain && dev->pm_domain->sync)
--
2.9.2