diff options
| author | Oliver Neukum <oneukum@suse.de> | 2015-03-20 09:24:24 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-26 10:50:52 +0100 |
| commit | 36e59e0d70d6150e7a2155c54612ea875e88ce8d (patch) | |
| tree | 210a79c37d9a262b1d6e8f37db2429c1c21edef7 | |
| parent | c0ab6bb0597363532f178f3cd7b7fb527eef39e2 (diff) | |
cdc-acm: fix race between callback and unthrottle
Abn URB may be may marked free only after the buffer has been
processed or there is a small window during which it could
be submitted on another CPU and overwrite an unprocessed buffer
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/class/cdc-acm.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 683617714e7c..58241ec1e91d 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -417,25 +417,33 @@ static void acm_read_bulk_callback(struct urb *urb) struct acm_rb *rb = urb->context; struct acm *acm = rb->instance; unsigned long flags; + int status = urb->status; dev_vdbg(&acm->data->dev, "%s - urb %d, len %d\n", __func__, rb->index, urb->actual_length); - set_bit(rb->index, &acm->read_urbs_free); if (!acm->dev) { + set_bit(rb->index, &acm->read_urbs_free); dev_dbg(&acm->data->dev, "%s - disconnected\n", __func__); return; } if (urb->status) { + set_bit(rb->index, &acm->read_urbs_free); dev_dbg(&acm->data->dev, "%s - non-zero urb status: %d\n", - __func__, urb->status); + __func__, status); return; } usb_mark_last_busy(acm->dev); acm_process_read_urb(acm, urb); + /* + * Unthrottle may run on another CPU which needs to see events + * in the same order. Submission has an implict barrier + */ + smp_mb__before_atomic(); + set_bit(rb->index, &acm->read_urbs_free); /* throttle device if requested by tty */ spin_lock_irqsave(&acm->read_lock, flags); |