driver core: add test of driver remove calls during probe

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@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 98504ec..fdf44ca 100644 (file)
--- 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 (file)
--- 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)