[PATCH v3 2/2] usb: chipidea: core: fix possible concurrent when switch role

[Xu Yang <xu.yang_2@xxxxxxx>]

The user may call role_store() when driver is handling
ci_handle_id_switch() which is triggerred by otg event or power lost
event. Unfortunately, the controller may go into chaos in this case.
Fix this by protecting it with mutex lock.

Fixes: a932a8041ff9 ("usb: chipidea: core: add sysfs group")
cc: <stable@xxxxxxxxxxxxxxx>
Acked-by: Peter Chen <peter.chen@xxxxxxxxxx>
Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>

---
changes since v1:
- modify description for mutex member
- wrap role variable in ci_handle_id_switch() too
changes since v2:
- add acked-by tag
---
 drivers/usb/chipidea/ci.h   | 2 ++
 drivers/usb/chipidea/core.c | 8 +++++++-
 drivers/usb/chipidea/otg.c  | 5 ++++-
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
index 005c67cb3afb..f210b7489fd5 100644
--- a/drivers/usb/chipidea/ci.h
+++ b/drivers/usb/chipidea/ci.h
@@ -208,6 +208,7 @@ struct hw_bank {
  * @in_lpm: if the core in low power mode
  * @wakeup_int: if wakeup interrupt occur
  * @rev: The revision number for controller
+ * @mutex: protect code from concorrent running when doing role switch
  */
 struct ci_hdrc {
 	struct device			*dev;
@@ -260,6 +261,7 @@ struct ci_hdrc {
 	bool				in_lpm;
 	bool				wakeup_int;
 	enum ci_revision		rev;
+	struct mutex                    mutex;
 };
 
 static inline struct ci_role_driver *ci_role(struct ci_hdrc *ci)
diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
index eae4bf865a8e..d1d252c87e4f 100644
--- a/drivers/usb/chipidea/core.c
+++ b/drivers/usb/chipidea/core.c
@@ -987,8 +987,12 @@ static ssize_t role_store(struct device *dev,
 	if (role == CI_ROLE_END)
 		return -EINVAL;
 
-	if (role == ci->role)
+	mutex_lock(&ci->mutex);
+
+	if (role == ci->role) {
+		mutex_unlock(&ci->mutex);
 		return n;
+	}
 
 	pm_runtime_get_sync(dev);
 	disable_irq(ci->irq);
@@ -998,6 +1002,7 @@ static ssize_t role_store(struct device *dev,
 		ci_handle_vbus_change(ci);
 	enable_irq(ci->irq);
 	pm_runtime_put_sync(dev);
+	mutex_unlock(&ci->mutex);
 
 	return (ret == 0) ? n : ret;
 }
@@ -1033,6 +1038,7 @@ static int ci_hdrc_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	spin_lock_init(&ci->lock);
+	mutex_init(&ci->mutex);
 	ci->dev = dev;
 	ci->platdata = dev_get_platdata(dev);
 	ci->imx28_write_fix = !!(ci->platdata->flags &
diff --git a/drivers/usb/chipidea/otg.c b/drivers/usb/chipidea/otg.c
index 622c3b68aa1e..f5490f2a5b6b 100644
--- a/drivers/usb/chipidea/otg.c
+++ b/drivers/usb/chipidea/otg.c
@@ -167,8 +167,10 @@ static int hw_wait_vbus_lower_bsv(struct ci_hdrc *ci)
 
 void ci_handle_id_switch(struct ci_hdrc *ci)
 {
-	enum ci_role role = ci_otg_role(ci);
+	enum ci_role role;
 
+	mutex_lock(&ci->mutex);
+	role = ci_otg_role(ci);
 	if (role != ci->role) {
 		dev_dbg(ci->dev, "switching from %s to %s\n",
 			ci_role(ci)->name, ci->roles[role]->name);
@@ -198,6 +200,7 @@ void ci_handle_id_switch(struct ci_hdrc *ci)
 		if (role == CI_ROLE_GADGET)
 			ci_handle_vbus_change(ci);
 	}
+	mutex_unlock(&ci->mutex);
 }
 /**
  * ci_otg_work - perform otg (vbus/id) event handle
-- 
2.34.1