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HID: uhid: Use READ_ONCE()/WRITE_ONCE() for ->running
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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>
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Jann Horn authored and Jiri Kosina committed Jan 19, 2022
1 parent 4ea5763 commit c8e7ff4
Showing 1 changed file with 10 additions and 10 deletions.
20 changes: 10 additions & 10 deletions drivers/hid/uhid.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
}
}
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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,
Expand All @@ -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,
Expand All @@ -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);
Expand All @@ -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);
Expand Down

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