Free old lease fd reference after transition

[src/drm-lease-manager.git] / drm-lease-manager / lease-manager.c

diff --git a/drm-lease-manager/lease-manager.c b/drm-lease-manager/lease-manager.c
index 6fafb46..5d79b8d 100644 (file)
--- a/drm-lease-manager/lease-manager.c
+++ b/drm-lease-manager/lease-manager.c
@@ -22,6 +22,8 @@
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <poll.h>
+#include <pthread.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
@@ -47,6 +49,11 @@ struct lease {
 
        uint32_t *object_ids;
        int nobject_ids;
+
+       /* for lease transfer completion */
+       uint32_t crtc_id;
+       pthread_t transition_tid;
+       bool transition_running;
 };
 
 struct lm {
@@ -199,6 +206,87 @@ static bool lease_add_planes(struct lm *lm, struct lease *lease, int crtc_index)
        return true;
 }
 
+/* Lease transition
+ * Wait for a client to update the DRM framebuffer on the CRTC managed by
+ * a lease.  Once the framebuffer has been updated, it is safe to close
+ * the fd associated with the previous lease client, freeing the previous
+ * framebuffer if there are no other references to it. */
+static void wait_for_fb_update(struct lease *lease, uint32_t old_fb)
+{
+       uint32_t current_fb = old_fb;
+
+       struct pollfd drm_poll = {
+           .fd = lease->lease_fd,
+           .events = POLLIN,
+       };
+
+       while (current_fb == old_fb) {
+               drmModeCrtcPtr crtc;
+               if (poll(&drm_poll, 1, -1) < 0) {
+                       if (errno == EINTR)
+                               continue;
+                       break;
+               }
+
+               crtc = drmModeGetCrtc(lease->lease_fd, lease->crtc_id);
+               current_fb = crtc->buffer_id;
+               drmModeFreeCrtc(crtc);
+       }
+}
+
+struct transition_ctx {
+       struct lease *lease;
+       int close_fd;
+       uint32_t old_fb;
+};
+
+static void transition_done(void *arg)
+{
+       struct transition_ctx *ctx = arg;
+       close(ctx->close_fd);
+       free(ctx);
+}
+
+static void *finish_transition_task(void *arg)
+{
+       struct transition_ctx *ctx = arg;
+       pthread_cleanup_push(transition_done, ctx);
+       wait_for_fb_update(ctx->lease, ctx->old_fb);
+       pthread_cleanup_pop(true);
+       return NULL;
+}
+
+static void close_after_lease_transition(struct lease *lease, int close_fd)
+{
+       struct transition_ctx *ctx = calloc(1, sizeof(*ctx));
+
+       assert(ctx);
+
+       drmModeCrtcPtr crtc = drmModeGetCrtc(lease->lease_fd, lease->crtc_id);
+
+       ctx->lease = lease;
+       ctx->close_fd = close_fd;
+       ctx->old_fb = crtc->buffer_id;
+
+       drmModeFreeCrtc(crtc);
+
+       int ret = pthread_create(&lease->transition_tid, NULL,
+                                finish_transition_task, ctx);
+
+       lease->transition_running = (ret == 0);
+}
+
+static void cancel_lease_transition_thread(struct lease *lease)
+{
+
+       if (lease->transition_running) {
+               pthread_cancel(lease->transition_tid);
+               pthread_join(lease->transition_tid, NULL);
+       }
+
+       lease->transition_running = false;
+}
+
 static void lease_free(struct lease *lease)
 {
        free(lease->base.name);
@@ -238,6 +326,7 @@ static struct lease *lease_create(struct lm *lm, drmModeConnectorPtr connector)
                goto err;
 
        uint32_t crtc_id = lm->drm_resource->crtcs[crtc_index];
+       lease->crtc_id = crtc_id;
        lease->object_ids[lease->nobject_ids++] = crtc_id;
        lease->object_ids[lease->nobject_ids++] = connector->connector_id;
 
@@ -381,8 +470,6 @@ int lm_lease_transfer(struct lm *lm, struct lease_handle *handle)
        if (!lease->is_granted)
                return -1;
 
-       // TODO: close this fd once a frame is presented from the new
-       //       client.
        int old_lease_fd = dup(lease->lease_fd);
 
        lm_lease_revoke(lm, handle);
@@ -391,6 +478,7 @@ int lm_lease_transfer(struct lm *lm, struct lease_handle *handle)
                return -1;
        }
 
+       close_after_lease_transition(lease, old_lease_fd);
        return lease->lease_fd;
 }
 
@@ -405,6 +493,7 @@ void lm_lease_revoke(struct lm *lm, struct lease_handle *handle)
                return;
 
        drmModeRevokeLease(lm->drm_fd, lease->lessee_id);
+       cancel_lease_transition_thread(lease);
        close(lease->lease_fd);
        lease->is_granted = false;
 }