destroyed shm segments in 2.2

[Christoph Rohland]

Hi Alan,

We just stumbled over the Linux 2.2 behaviour that you cannot create a
shm segment with a key of a destroyed segment. This breaks some
applications.

Could we change the behaviour in 2.2 like we did it in 2.3 and make it
more compatible with other UN*Xes? The attached (untested) patch
should implement the 2.4 behaviour.

Greetings
                Christoph


--- linux/ipc/shm.c.orig        Wed Oct  4 14:23:08 2000
+++ linux/ipc/shm.c     Wed Oct  4 14:25:24 2000
@@ -161,9 +161,7 @@
                err = -EEXIST;
        } else {
                shp = shm_segs[id];
-               if (shp->u.shm_perm.mode & SHM_DEST)
-                       err = -EIDRM;
-               else if (size > shp->u.shm_segsz)
+               if (size > shp->u.shm_segsz)
                        err = -EINVAL;
                else if (ipcperms (&shp->u.shm_perm, shmflg))
                        err = -EACCES;
@@ -341,6 +339,7 @@
                    current->euid == shp->u.shm_perm.cuid || 
                    capable(CAP_SYS_ADMIN)) {
                        shp->u.shm_perm.mode |= SHM_DEST;
+                       shp->u.shm_perm.key = IPC_PRIVATE;
                        if (shp->u.shm_nattch <= 0)
                                killseg (id);
                        break;