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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2012-10-19 12:04:50 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2012-10-19 12:04:50 +0100 |
| commit | 5041b462d084de8552336275914d30c23bf5dd35 (patch) | |
| tree | 51e0950541326d1ffc19aa35a64ea98d613d2869 | |
| parent | d5f9c694b9145f0464c8bd58d844bddedcb77d5e (diff) | |
| download | cairo-5041b462d084de8552336275914d30c23bf5dd35.tar.gz | |
xlib/shm: Sync the XShmAttach before removing the ShmSegment id
Whilst reading through other users of XShm, it became apparent that
IPC_RMID behaves differently across the platforms. Linux allows
processes to attach to an existing ShmSegment id after a IPC_RMID, but
for others the IPC_RMID takes immediate effect. On those platforms
without a "deferred" IPC_RMID, we then need to perform the XShmAttach
synchronously before perfomring the IPC_RMID.
Reported-by: Thomas Klausner <wiz@NetBSD.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
| -rw-r--r-- | configure.ac | 32 | ||||
| -rw-r--r-- | src/cairo-xlib-surface-shm.c | 3 |
2 files changed, 35 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 67b68e2d6..017e81af5 100644 --- a/configure.ac +++ b/configure.ac @@ -74,6 +74,38 @@ CAIRO_ENABLE_SURFACE_BACKEND(xlib, Xlib, auto, [ xlib_NONPKGCONFIG_LIBS="$X_PRE_LIBS $X_LIBS -lX11 -lXext $X_EXTRA_LIBS" xlib_NONPKGCONFIG_CFLAGS=$X_CFLAGS fi]) + + AC_CHECK_HEADER(sys/ipc.h) + AC_CHECK_HEADER(sys/shm.h) + + if test "$ac_cv_header_sys_ipc_h" = "yes" -a "$ac_cv_header_sys_shm_h" = "yes"; then + AC_MSG_CHECKING(whether shmctl IPC_RMID allowes subsequent attaches) + AC_TRY_RUN([ + #include <sys/types.h> + #include <sys/ipc.h> + #include <sys/shm.h> + int main() + { + char *shmaddr; + int id = shmget (IPC_PRIVATE, 4, IPC_CREAT | 0600); + if (id == -1) return 2; + shmaddr = shmat (id, 0, 0); + shmctl (id, IPC_RMID, 0); + if ((char*) shmat (id, 0, 0) == (char*) -1) { + shmdt (shmaddr); + return 1; + } + shmdt (shmaddr); + shmdt (shmaddr); + return 0; + } + ], + AC_DEFINE(IPC_RMID_DEFERRED_RELEASE, 1, + [Define to 1 if shared memory segments are released deferred.]) + AC_MSG_RESULT(yes), + AC_MSG_RESULT(no), + AC_MSG_RESULT(assuming no)) + fi ]) CAIRO_ENABLE_SURFACE_BACKEND(xlib_xrender, Xlib Xrender, auto, [ diff --git a/src/cairo-xlib-surface-shm.c b/src/cairo-xlib-surface-shm.c index ec8a6e1dd..ec0d334ef 100644 --- a/src/cairo-xlib-surface-shm.c +++ b/src/cairo-xlib-surface-shm.c @@ -449,6 +449,9 @@ _cairo_xlib_shm_pool_create(cairo_xlib_display_t *display, pool->attached = NextRequest (dpy); success = XShmAttach (dpy, &pool->shm); +#if !IPC_RMID_DEFERRED_RELEASE + XSync (dpy, FALSE); +#endif shmctl (pool->shm.shmid, IPC_RMID, NULL); if (! success) |