diff options
| -rw-r--r-- | drivers/rpmsg/virtio_rpmsg_bus.c | 55 | ||||
| -rw-r--r-- | include/linux/rpmsg.h | 6 |
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; }; |