HID: uhid: Use READ_ONCE()/WRITE_ONCE() for ->running

The flag uhid->running can be set to false by uhid_device_add_worker()
without holding the uhid->devlock. Mark all reads/writes of the flag
that might race with READ_ONCE()/WRITE_ONCE() for clarity and
correctness.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
index fc06d8b..614adb5 100644 (file)
--- a/drivers/hid/uhid.c
+++ b/drivers/hid/uhid.c
@@ -84,7 +84,7 @@ static void uhid_device_add_worker(struct work_struct *work)
                 * However, we do have to clear the ->running flag and do a
                 * wakeup to make sure userspace knows that the device is gone.
                 */
-               uhid->running = false;
+               WRITE_ONCE(uhid->running, false);
                wake_up_interruptible(&uhid->report_wait);
        }
 }
@@ -194,9 +194,9 @@ static int __uhid_report_queue_and_wait(struct uhid_device *uhid,
        spin_unlock_irqrestore(&uhid->qlock, flags);
 
        ret = wait_event_interruptible_timeout(uhid->report_wait,
-                               !uhid->report_running || !uhid->running,
+                               !uhid->report_running || !READ_ONCE(uhid->running),
                                5 * HZ);
-       if (!ret || !uhid->running || uhid->report_running)
+       if (!ret || !READ_ONCE(uhid->running) || uhid->report_running)
                ret = -EIO;
        else if (ret < 0)
                ret = -ERESTARTSYS;
@@ -237,7 +237,7 @@ static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum,
        struct uhid_event *ev;
        int ret;
 
-       if (!uhid->running)
+       if (!READ_ONCE(uhid->running))
                return -EIO;
 
        ev = kzalloc(sizeof(*ev), GFP_KERNEL);
@@ -279,7 +279,7 @@ static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum,
        struct uhid_event *ev;
        int ret;
 
-       if (!uhid->running || count > UHID_DATA_MAX)
+       if (!READ_ONCE(uhid->running) || count > UHID_DATA_MAX)
                return -EIO;
 
        ev = kzalloc(sizeof(*ev), GFP_KERNEL);
@@ -579,7 +579,7 @@ static int uhid_dev_destroy(struct uhid_device *uhid)
        if (!uhid->hid)
                return -EINVAL;
 
-       uhid->running = false;
+       WRITE_ONCE(uhid->running, false);
        wake_up_interruptible(&uhid->report_wait);
 
        cancel_work_sync(&uhid->worker);
@@ -593,7 +593,7 @@ static int uhid_dev_destroy(struct uhid_device *uhid)
 
 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
 {
-       if (!uhid->running)
+       if (!READ_ONCE(uhid->running))
                return -EINVAL;
 
        hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
@@ -604,7 +604,7 @@ static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
 
 static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev)
 {
-       if (!uhid->running)
+       if (!READ_ONCE(uhid->running))
                return -EINVAL;
 
        hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data,
@@ -616,7 +616,7 @@ static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev)
 static int uhid_dev_get_report_reply(struct uhid_device *uhid,
                                     struct uhid_event *ev)
 {
-       if (!uhid->running)
+       if (!READ_ONCE(uhid->running))
                return -EINVAL;
 
        uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev);
@@ -626,7 +626,7 @@ static int uhid_dev_get_report_reply(struct uhid_device *uhid,
 static int uhid_dev_set_report_reply(struct uhid_device *uhid,
                                     struct uhid_event *ev)
 {
-       if (!uhid->running)
+       if (!READ_ONCE(uhid->running))
                return -EINVAL;
 
        uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev);