[Buildroot] [PATCH] sdl2: add patch to fix busy-loop in C library

[Paul Cercueil]

For some obscure reason, the order in which the libdrm/libgbm libraries
are loaded matters.

Without this fix, the first call to check_modesetting() will work and
load then unload all symbols properly, but the second call to this
function will lock up as soon as dlopen() is called on libdrm.

Swapping the order in which the libdrm and libgbm libraries are loaded
is enough to fix (or work around?) this issue.

Signed-off-by: Paul Cercueil <paul at crapouillou.net>
---
 .../sdl2/0002-fix-busy-loop-in-dlopen.patch   | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 package/sdl2/0002-fix-busy-loop-in-dlopen.patch

diff --git a/package/sdl2/0002-fix-busy-loop-in-dlopen.patch b/package/sdl2/0002-fix-busy-loop-in-dlopen.patch
new file mode 100644
index 0000000000..984a80d9c1
--- /dev/null
+++ b/package/sdl2/0002-fix-busy-loop-in-dlopen.patch
@@ -0,0 +1,37 @@
+
+# HG changeset patch
+# User Paul Cercueil <paul at crapouillou.net>
+# Date 1576820863 28800
+# Node ID 4f5bef55183c677d12a7da8f3392879ed50670a3
+# Parent  01f16d7f36cb9f4fa02016e57fbe915fdea71cc8
+kmsdrm: Fix busy-loop within libc's dlopen()
+For some obscure reason, the order in which the libdrm/libgbm libraries
+are loaded matters.
+
+Without this fix, the first call to check_modesetting() will work and
+load then unload all symbols properly, but the second call to this
+function will lock up as soon as dlopen() is called on libdrm.
+
+Swapping the order in which the libdrm and libgbm libraries are loaded
+is enough to fix (or work around?) this issue.
+
+Fixes #4891:
+https://bugzilla.libsdl.org/show_bug.cgi?id=4891
+
+Signed-off-by: Paul Cercueil <paul at crapouillou.net>
+
+diff -r 01f16d7f36cb -r 4f5bef55183c src/video/kmsdrm/SDL_kmsdrmdyn.c
+--- a/src/video/kmsdrm/SDL_kmsdrmdyn.c	Thu Dec 19 21:45:44 2019 -0800
++++ b/src/video/kmsdrm/SDL_kmsdrmdyn.c	Thu Dec 19 21:47:43 2019 -0800
+@@ -50,8 +50,8 @@
+ #endif
+ 
+ static kmsdrmdynlib kmsdrmlibs[] = {
+-    {NULL, SDL_VIDEO_DRIVER_KMSDRM_DYNAMIC},
+-    {NULL, SDL_VIDEO_DRIVER_KMSDRM_DYNAMIC_GBM}
++    {NULL, SDL_VIDEO_DRIVER_KMSDRM_DYNAMIC_GBM},
++    {NULL, SDL_VIDEO_DRIVER_KMSDRM_DYNAMIC}
+ };
+ 
+ static void *
+
-- 
2.24.0