compositor-drm: Avoid output_destroy happened before page_flip event

Currently there is no guarentee that output remove event always happend after
page_flip event on the same output. So if the following situation occur:

  first: unplug a output
  second: output remove event arrive, output_destrory called adn free output
  third: page_flip event arrive on the destroyed output

the segment fault will happpen in page_flip_handler().

This patch add a variable drm_compositor->destroy_pending, if page flip
event is pending when output remove event arrive, output_destroy will be
delayed until page flip finished.

Signed-off-by: Xiong Zhang <xiong.y.zhang@intel.com>

diff --git a/src/compositor-drm.c b/src/compositor-drm.c
index 0ac5efa..ffdec89 100644 (file)
--- a/src/compositor-drm.c
+++ b/src/compositor-drm.c
@@ -149,6 +149,7 @@ struct drm_output {
 
        int vblank_pending;
        int page_flip_pending;
+       int destroy_pending;
 
        struct gbm_surface *surface;
        struct gbm_bo *cursor_bo[2];
@@ -577,6 +578,9 @@ drm_output_repaint(struct weston_output *output_base,
        struct drm_mode *mode;
        int ret = 0;
 
+       if (output->destroy_pending)
+               return;
+
        if (!output->next)
                drm_output_render(output, damage);
        if (!output->next)
@@ -664,6 +668,9 @@ drm_output_start_repaint_loop(struct weston_output *output_base)
 
        struct timespec ts;
 
+       if (output->destroy_pending)
+               return;
+
        if (!output->current) {
                /* We can't page flip if there's no mode set */
                uint32_t msec;
@@ -704,6 +711,9 @@ vblank_handler(int fd, unsigned int frame, unsigned int sec, unsigned int usec,
 }
 
 static void
+drm_output_destroy(struct weston_output *output_base);
+
+static void
 page_flip_handler(int fd, unsigned int frame,
                  unsigned int sec, unsigned int usec, void *data)
 {
@@ -721,7 +731,9 @@ page_flip_handler(int fd, unsigned int frame,
 
        output->page_flip_pending = 0;
 
-       if (!output->vblank_pending) {
+       if (output->destroy_pending)
+               drm_output_destroy(&output->base);
+       else if (!output->vblank_pending) {
                msecs = sec * 1000 + usec / 1000;
                weston_output_finish_frame(&output->base, msecs);
 
@@ -1063,6 +1075,12 @@ drm_output_destroy(struct weston_output *output_base)
                (struct drm_compositor *) output->base.compositor;
        drmModeCrtcPtr origcrtc = output->original_crtc;
 
+       if (output->page_flip_pending) {
+               output->destroy_pending = 1;
+               weston_log("destroy output while page flip pending\n");
+               return;
+       }
+
        if (output->backlight)
                backlight_destroy(output->backlight);