rpmsg: make sure inflight messages don't invoke just-removed callbacks
When inbound messages arrive, rpmsg core looks up their associated
endpoint (by destination address) and then invokes their callback.
We've made sure that endpoints will never be de-allocated after they
were found by rpmsg core, but we also need to protect against the
(rare) scenario where the rpmsg driver was just removed, and its
callback function isn't available anymore.
This is achieved by introducing a callback mutex, which must be taken
before the callback is invoked, and, obviously, before it is removed.
Cc: stable <stable@vger.kernel.org>
Reported-by: Fernando Guzman Lugo <fernando.lugo@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index 9623327..39d3aa4 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -227,6 +227,7 @@
}
kref_init(&ept->refcount);
+ mutex_init(&ept->cb_lock);
ept->rpdev = rpdev;
ept->cb = cb;
@@ -324,10 +325,16 @@
static void
__rpmsg_destroy_ept(struct virtproc_info *vrp, struct rpmsg_endpoint *ept)
{
+ /* make sure new inbound messages can't find this ept anymore */
mutex_lock(&vrp->endpoints_lock);
idr_remove(&vrp->endpoints, ept->addr);
mutex_unlock(&vrp->endpoints_lock);
+ /* make sure in-flight inbound messages won't invoke cb anymore */
+ mutex_lock(&ept->cb_lock);
+ ept->cb = NULL;
+ mutex_unlock(&ept->cb_lock);
+
kref_put(&ept->refcount, __ept_release);
}
@@ -821,14 +828,20 @@
mutex_unlock(&vrp->endpoints_lock);
- if (ept && ept->cb)
- ept->cb(ept->rpdev, msg->data, msg->len, ept->priv, msg->src);
- else
- dev_warn(dev, "msg received with no recepient\n");
+ if (ept) {
+ /* make sure ept->cb doesn't go away while we use it */
+ mutex_lock(&ept->cb_lock);
- /* farewell, ept, we don't need you anymore */
- if (ept)
+ if (ept->cb)
+ ept->cb(ept->rpdev, msg->data, msg->len, ept->priv,
+ msg->src);
+
+ mutex_unlock(&ept->cb_lock);
+
+ /* farewell, ept, we don't need you anymore */
kref_put(&ept->refcount, __ept_release);
+ } else
+ dev_warn(dev, "msg received with no recepient\n");
/* publish the real size of the buffer */
sg_init_one(&sg, msg, RPMSG_BUF_SIZE);