st/wgl: refactor framebuffer locking code

Split the old stw_framebuffer_reference() function into two new
functions: stw_framebuffer_reference_locked() which increments
the refcount and stw_framebuffer_release_locked() which decrements
the refcount and destroys the buffer when the count hits zero.

Original patch by Jose.  Modified by Brian (clean-ups, lock assertion
checks, etc).

Reviewed-by: José Fonseca <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/gallium/state_trackers/wgl/stw_device.h b/src/gallium/state_trackers/wgl/stw_device.h
index 3f0dffe408b..15d66a24e5d 100644
--- a/src/gallium/state_trackers/wgl/stw_device.h
+++ b/src/gallium/state_trackers/wgl/stw_device.h
@@ -67,6 +67,10 @@ struct stw_device
    CRITICAL_SECTION ctx_mutex;
    struct handle_table *ctx_table;
    
+   /* TODO: use an atomic counter to track the number of locked
+    * stw_framebuffer objects.  Assert that the counter is zero when
+    * trying to lock this mutex.
+    */
    CRITICAL_SECTION fb_mutex;
    struct stw_framebuffer *fb_head;