On 2018-12-19 7:19 p.m., Lyude Paul wrote:
> Up until now, freeing payloads on remote MST hubs that just had ports
> removed has almost never worked because we've been relying on port
> validation in order to stop us from accessing ports that have already
> been freed from memory, but ports which need their payloads released due
> to being removed will never be a valid part of the topology after
> they've been removed.
>
> Since we've introduced malloc refs, we can replace all of the validation
> logic in payload helpers which are used for deallocation with some
> well-placed malloc krefs. This ensures that regardless of whether or not
> the ports are still valid and in the topology, any port which has an
> allocated payload will remain allocated in memory until it's payloads
> have been removed - finally allowing us to actually release said
> payloads correctly.
>
> Signed-off-by: Lyude Paul <ly...@redhat.com>
> Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>
> Cc: David Airlie <airl...@redhat.com>
> Cc: Jerry Zuo <jerry....@amd.com>
> Cc: Harry Wentland <harry.wentl...@amd.com>
> Cc: Juston Li <juston...@intel.com>
Reviewed-by: Harry Wentland <harry.wentl...@amd.com>
Harry
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 54 +++++++++++++++------------
> 1 file changed, 30 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> b/drivers/gpu/drm/drm_dp_mst_topology.c
> index ef8637f37564..11dd3ede7b7d 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2100,10 +2100,6 @@ static int drm_dp_payload_send_msg(struct
> drm_dp_mst_topology_mgr *mgr,
> u8 sinks[DRM_DP_MAX_SDP_STREAMS];
> int i;
>
> - port = drm_dp_mst_topology_get_port_validated(mgr, port);
> - if (!port)
> - return -EINVAL;
> -
> port_num = port->port_num;
> mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
> if (!mstb) {
> @@ -2111,10 +2107,8 @@ static int drm_dp_payload_send_msg(struct
> drm_dp_mst_topology_mgr *mgr,
> port->parent,
> &port_num);
>
> - if (!mstb) {
> - drm_dp_mst_topology_put_port(port);
> + if (!mstb)
> return -EINVAL;
> - }
> }
>
> txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
> @@ -2151,7 +2145,6 @@ static int drm_dp_payload_send_msg(struct
> drm_dp_mst_topology_mgr *mgr,
> kfree(txmsg);
> fail_put:
> drm_dp_mst_topology_put_mstb(mstb);
> - drm_dp_mst_topology_put_port(port);
> return ret;
> }
>
> @@ -2256,15 +2249,16 @@ static int drm_dp_destroy_payload_step2(struct
> drm_dp_mst_topology_mgr *mgr,
> */
> int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
> {
> - int i, j;
> - int cur_slots = 1;
> struct drm_dp_payload req_payload;
> struct drm_dp_mst_port *port;
> + int i, j;
> + int cur_slots = 1;
>
> mutex_lock(&mgr->payload_lock);
> for (i = 0; i < mgr->max_payloads; i++) {
> struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
> struct drm_dp_payload *payload = &mgr->payloads[i];
> + bool put_port = false;
>
> /* solve the current payloads - compare to the hw ones
> - update the hw view */
> @@ -2272,12 +2266,20 @@ int drm_dp_update_payload_part1(struct
> drm_dp_mst_topology_mgr *mgr)
> if (vcpi) {
> port = container_of(vcpi, struct drm_dp_mst_port,
> vcpi);
> - port = drm_dp_mst_topology_get_port_validated(mgr,
> - port);
> - if (!port) {
> - mutex_unlock(&mgr->payload_lock);
> - return -EINVAL;
> +
> + /* Validated ports don't matter if we're releasing
> + * VCPI
> + */
> + if (vcpi->num_slots) {
> + port = drm_dp_mst_topology_get_port_validated(
> + mgr, port);
> + if (!port) {
> + mutex_unlock(&mgr->payload_lock);
> + return -EINVAL;
> + }
> + put_port = true;
> }
> +
> req_payload.num_slots = vcpi->num_slots;
> req_payload.vcpi = vcpi->vcpi;
> } else {
> @@ -2309,7 +2311,7 @@ int drm_dp_update_payload_part1(struct
> drm_dp_mst_topology_mgr *mgr)
> }
> cur_slots += req_payload.num_slots;
>
> - if (port)
> + if (put_port)
> drm_dp_mst_topology_put_port(port);
> }
>
> @@ -3124,6 +3126,8 @@ bool drm_dp_mst_allocate_vcpi(struct
> drm_dp_mst_topology_mgr *mgr,
> DRM_DEBUG_KMS("initing vcpi for pbn=%d slots=%d\n",
> pbn, port->vcpi.num_slots);
>
> + /* Keep port allocated until it's payload has been removed */
> + drm_dp_mst_get_port_malloc(port);
> drm_dp_mst_topology_put_port(port);
> return true;
> out:
> @@ -3153,11 +3157,12 @@ EXPORT_SYMBOL(drm_dp_mst_get_vcpi_slots);
> */
> void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct
> drm_dp_mst_port *port)
> {
> - port = drm_dp_mst_topology_get_port_validated(mgr, port);
> - if (!port)
> - return;
> + /*
> + * A port with VCPI will remain allocated until it's VCPI is
> + * released, no verified ref needed
> + */
> +
> port->vcpi.num_slots = 0;
> - drm_dp_mst_topology_put_port(port);
> }
> EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
>
> @@ -3169,16 +3174,17 @@ EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
> void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
> struct drm_dp_mst_port *port)
> {
> - port = drm_dp_mst_topology_get_port_validated(mgr, port);
> - if (!port)
> - return;
> + /*
> + * A port with VCPI will remain allocated until it's VCPI is
> + * released, no verified ref needed
> + */
>
> drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
> port->vcpi.num_slots = 0;
> port->vcpi.pbn = 0;
> port->vcpi.aligned_pbn = 0;
> port->vcpi.vcpi = 0;
> - drm_dp_mst_topology_put_port(port);
> + drm_dp_mst_put_port_malloc(port);
> }
> EXPORT_SYMBOL(drm_dp_mst_deallocate_vcpi);
>
>
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