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Sam Lantinga 063f752e0d Fixed bug 3328 - Race condition in Wayland_VideoInit
Robert Folland

When running this little test program with SDL2 on Wayland it often crashes in SDL_Init.

From a backtrace it is apparent that there is a race condition in creating a xkb_context_ref. Sometimes it is 0x0.

By moving the relevant lines higher up in Wayland_VideoInit (in SDL2-2.0.4/src/video/wayland/SDL_waylandvideo.c:302) this seems to get fixed.

I moved the call to WAYLAND_xkb_context_new() up to before the call to WAYLAND_wl_display_connect().

Here is the test program (just a loop of init and quit), and a backtrace from gdb:

#include <cstdio>
#include <stdlib.h>
#include <SDL2/SDL.h>
#include <unistd.h>
#include <iostream>

int main(int argc, char **argv)
{
    int count = atoi(argv[1]);

    for (int i = 0; i < count; i++) {
        std::cout << "Init " << i << std::endl;
        if (SDL_Init(SDL_INIT_VIDEO) < 0) {
            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
                         "Couldn't initialize SDL: %s\n",
                         SDL_GetError());
            return 1;
        }
        std::cout << "Quit" << std::endl;
        SDL_Quit();
    }
    return 0;
}


Init 12
Quit
Init 13

Program received signal SIGSEGV, Segmentation fault.
xkb_context_ref (ctx=ctx@entry=0x0) at src/context.c:156
156         ctx->refcnt++;
(gdb) bt
#0  xkb_context_ref (ctx=ctx@entry=0x0) at src/context.c:156
#1  0x00007ffff5e1cd4c in xkb_keymap_new (ctx=0x0, format=XKB_KEYMAP_FORMAT_TEXT_V1, flags=flags@entry=XKB_KEYMAP_COMPILE_NO_FLAGS) at src/keymap-priv.c:65
#2  0x00007ffff5e1c6cc in xkb_keymap_new_from_buffer (ctx=<optimized out>,
    buffer=0x7ffff7fd5000 "xkb_keymap {\nxkb_keycodes \"(unnamed)\" {\n\tminimum = 8;\n\tmaximum = 255;\n\t<ESC>", ' ' <repeats 16 times>, "= 9;\n\t<AE01>", ' ' <re
peats 15 times>, "= 10;\n\t<AE02>", ' ' <repeats 15 times>, "= 11;\n\t<AE03>", ' ' <repeats 15 times>, "= 12;\n\t<AE04>", ' ' <repeats 12 times>..., length=48090,
    format=<optimized out>, flags=<optimized out>) at src/keymap.c:191
#3  0x00007ffff7b8ea4e in keyboard_handle_keymap (data=0x6169b0, keyboard=<optimized out>, format=<optimized out>, fd=5, size=48091)
    at /home/vlab/abs/sdl2/src/SDL2-2.0.4/src/video/wayland/SDL_waylandevents.c:269
#4  0x00007ffff64501f0 in ffi_call_unix64 () from /usr/lib/libffi.so.6
#5  0x00007ffff644fc58 in ffi_call () from /usr/lib/libffi.so.6
#6  0x00007ffff665be3e in wl_closure_invoke (closure=closure@entry=0x61f000, flags=flags@entry=1, target=<optimized out>, target@entry=0x616d20,
    opcode=opcode@entry=0, data=<optimized out>) at src/connection.c:949
#7  0x00007ffff6658be0 in dispatch_event (display=<optimized out>, queue=<optimized out>) at src/wayland-client.c:1274
#8  0x00007ffff6659db4 in dispatch_queue (queue=0x617398, display=0x6172d0) at src/wayland-client.c:1420
#9  wl_display_dispatch_queue_pending (display=0x6172d0, queue=0x617398) at src/wayland-client.c:1662
#10 0x00007ffff665a0cf in wl_display_roundtrip_queue (display=0x6172d0, queue=0x617398) at src/wayland-client.c:1085
#11 0x00007ffff7b8faa0 in Wayland_VideoInit (_this=<optimized out>) at /home/vlab/abs/sdl2/src/SDL2-2.0.4/src/video/wayland/SDL_waylandvideo.c:302
#12 0x00007ffff7b7aed6 in SDL_VideoInit_REAL (driver_name=<optimized out>, driver_name@entry=0x0) at /home/vlab/abs/sdl2/src/SDL2-2.0.4/src/video/SDL_video.c:513
#13 0x00007ffff7ae0ee7 in SDL_InitSubSystem_REAL (flags=16416) at /home/vlab/abs/sdl2/src/SDL2-2.0.4/src/SDL.c:173
#14 0x0000000000400b24 in main (argc=2, argv=0x7fffffffebb8) at vplay-init.cpp:13
(gdb)
2016-10-13 04:54:43 -07:00
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VisualC-WinRT Merge audio capture work back into the mainline. 2016-08-28 13:36:13 -04:00
Xcode Build SDL as universal binary 2016-10-12 18:46:17 -07:00
Xcode-iOS iOS: Updated demo README. 2016-10-09 20:30:49 +02:00
acinclude Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
android-project Android: Fixed compile error. 2016-10-02 22:32:50 +02:00
build-scripts Fixed bug 3276 - build-scripts/showrev.sh prints the tip, which isn't useful if you're on a different -# branch, or just not sync'd to the tip. 2016-10-01 12:52:55 -07:00
cmake cmake: Now generates Wayland protocol source bits like the configure script. 2016-10-11 16:36:40 -04:00
debian Replaced SDL_qsort with public domain code from PDCLib: http://pdclib.e43.eu/ 2016-02-15 03:16:46 -05:00
docs Fixed building and using fcitx IME support on Linux 2016-10-08 11:30:07 -07:00
include Fixed comment for new pixel formats 2016-10-11 23:21:41 -07:00
premake Fixed bug 3262 - Premake scripts are not compatible with "Genie" (premake fork) 2016-10-01 12:56:28 -07:00
src Fixed bug 3328 - Race condition in Wayland_VideoInit 2016-10-13 04:54:43 -07:00
test Fixed black screen on Steam Link 2016-10-13 04:01:25 -07:00
visualtest Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
.hgignore audio: Initial bits to enable audio capture support. 2016-08-01 00:18:56 -04:00
Android.mk Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
BUGS.txt BUGS.txt: Bugzilla supports SSL; changed link to https:// ... 2016-08-01 13:36:43 -04:00
CMakeLists.txt Fixed setting the version info in the shared library when using CMake 2016-10-03 03:42:10 -07:00
COPYING.txt Updated copyright to 2016 2016-01-02 10:10:34 -08:00
CREDITS.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
INSTALL.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
Makefile.in wayland: Build own version of core protocol 2016-06-23 18:39:05 +08:00
Makefile.minimal Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
Makefile.pandora Pandora: Fixed referring to no more existing atomic source file in Makefile. 2016-07-19 21:01:13 +02:00
Makefile.psp PSP: Added missing object for generic TLS to Makefile. 2016-02-13 17:34:14 +01:00
Makefile.wiz Pandora: Updated SDL version in Makefile. 2016-07-19 21:01:30 +02:00
README-SDL.txt Another commit to test revision control. 2016-03-08 20:26:26 -05:00
README.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
SDL2.spec.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
TODO.txt Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
VisualC.html Fixed two typos in documentation. 2016-01-12 22:23:53 +01:00
WhatsNew.txt Added note for David Carlier's work on OpenBSD 2016-10-12 18:57:12 -07:00
autogen.sh Fix running autogen.sh out-of-tree 2016-10-01 10:39:03 -07:00
cmake_uninstall.cmake.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
configure Fixed bug 2824 - Add Fcitx Input Method Support 2016-10-07 18:57:40 -07:00
configure.in Fixed bug 2824 - Add Fcitx Input Method Support 2016-10-07 18:57:40 -07:00
sdl2-config.cmake.in Applied Ubuntu patch bug_822210_fix_sdl2-config.cmake_whitespace.patch 2016-10-07 15:08:37 -07:00
sdl2-config.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00
sdl2.m4 Fixed bug 3429 - Update AM_PATH_SDL2() to also check for SDL2.framework 2016-09-29 16:37:08 -07:00
sdl2.pc.in Fixed crash if initialization of EGL failed but was tried again later. 2015-06-21 17:33:46 +02:00

README.txt

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                         Simple DirectMedia Layer

                                  (SDL)

                                Version 2.0

---
http://www.libsdl.org/

Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.

More extensive documentation is available in the docs directory, starting
with README.md

Enjoy!
	Sam Lantinga				(slouken@libsdl.org)