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-rw-r--r--drivers/rpmsg/virtio_rpmsg_bus.c55
-rw-r--r--include/linux/rpmsg.h6
2 files changed, 56 insertions, 5 deletions
diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index 75506ec2840e..39d3aa41adda 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -188,6 +188,26 @@ static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
rpdev->id.name);
}
+/**
+ * __ept_release() - deallocate an rpmsg endpoint
+ * @kref: the ept's reference count
+ *
+ * This function deallocates an ept, and is invoked when its @kref refcount
+ * drops to zero.
+ *
+ * Never invoke this function directly!
+ */
+static void __ept_release(struct kref *kref)
+{
+ struct rpmsg_endpoint *ept = container_of(kref, struct rpmsg_endpoint,
+ refcount);
+ /*
+ * At this point no one holds a reference to ept anymore,
+ * so we can directly free it
+ */
+ kfree(ept);
+}
+
/* for more info, see below documentation of rpmsg_create_ept() */
static struct rpmsg_endpoint *__rpmsg_create_ept(struct virtproc_info *vrp,
struct rpmsg_channel *rpdev, rpmsg_rx_cb_t cb,
@@ -206,6 +226,9 @@ static struct rpmsg_endpoint *__rpmsg_create_ept(struct virtproc_info *vrp,
return NULL;
}
+ kref_init(&ept->refcount);
+ mutex_init(&ept->cb_lock);
+
ept->rpdev = rpdev;
ept->cb = cb;
ept->priv = priv;
@@ -238,7 +261,7 @@ rem_idr:
idr_remove(&vrp->endpoints, request);
free_ept:
mutex_unlock(&vrp->endpoints_lock);
- kfree(ept);
+ kref_put(&ept->refcount, __ept_release);
return NULL;
}
@@ -302,11 +325,17 @@ EXPORT_SYMBOL(rpmsg_create_ept);
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);
- kfree(ept);
+ /* 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);
}
/**
@@ -790,12 +819,28 @@ static void rpmsg_recv_done(struct virtqueue *rvq)
/* use the dst addr to fetch the callback of the appropriate user */
mutex_lock(&vrp->endpoints_lock);
+
ept = idr_find(&vrp->endpoints, msg->dst);
+
+ /* let's make sure no one deallocates ept while we use it */
+ if (ept)
+ kref_get(&ept->refcount);
+
mutex_unlock(&vrp->endpoints_lock);
- if (ept && ept->cb)
- ept->cb(ept->rpdev, msg->data, msg->len, ept->priv, msg->src);
- else
+ if (ept) {
+ /* make sure ept->cb doesn't go away while we use it */
+ mutex_lock(&ept->cb_lock);
+
+ 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 */
diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index a8e50e44203c..82a673905edb 100644
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h
@@ -38,6 +38,8 @@
#include <linux/types.h>
#include <linux/device.h>
#include <linux/mod_devicetable.h>
+#include <linux/kref.h>
+#include <linux/mutex.h>
/* The feature bitmap for virtio rpmsg */
#define VIRTIO_RPMSG_F_NS 0 /* RP supports name service notifications */
@@ -120,7 +122,9 @@ typedef void (*rpmsg_rx_cb_t)(struct rpmsg_channel *, void *, int, void *, u32);
/**
* struct rpmsg_endpoint - binds a local rpmsg address to its user
* @rpdev: rpmsg channel device
+ * @refcount: when this drops to zero, the ept is deallocated
* @cb: rx callback handler
+ * @cb_lock: must be taken before accessing/changing @cb
* @addr: local rpmsg address
* @priv: private data for the driver's use
*
@@ -140,7 +144,9 @@ typedef void (*rpmsg_rx_cb_t)(struct rpmsg_channel *, void *, int, void *, u32);
*/
struct rpmsg_endpoint {
struct rpmsg_channel *rpdev;
+ struct kref refcount;
rpmsg_rx_cb_t cb;
+ struct mutex cb_lock;
u32 addr;
void *priv;
};