Re: bin/58024: wg-userspace N destroy fails to destroy tun interface created by wg-userspace N create

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

The EEXIST happens because of all this crud in the opencrypto rump
component, used to create the /dev/crypto node in the rump system's
namespace:

https://nxr.netbsd.org/xref/src/sys/rump/dev/lib/libopencrypto/opencrypto_component.c?r=1.6#54

     54 	if ((error = devsw_attach("crypto", NULL, &bmaj,
     55 	    &crypto_cdevsw, &cmaj)) != 0)
     56 		panic("cannot attach crypto: %d", error);
     57 
     58 	if ((error = rump_vfs_makeonedevnode(S_IFCHR, "/dev/crypto",
     59 	    cmaj, 0)) != 0)
     60 		panic("cannot create /dev/crypto: %d", error);
     61 
     62 	/*
     63 	 * Initialize OpenCrypto and its pseudo-devices here
     64 	 */
     65 	crypto_init();
     66 	rump_pdev_add(cryptoattach, 1);
     67 #if 0
     68 	/*
     69 	 * rump defines "_MODULE" in spite of using built-in module
     70 	 * initialization(module_init_class()). So, swcryptoattach_internal()
     71 	 * is called by two functions, one is swcryptoattach() and the other is
     72 	 * swcrypto_modcmd().
     73 	 * That causes "builtin module `swcrypto' failed to init" WARNING message.
     74 	 * To suppress this warning, we let rump use swcrypto_modcmd() call-path
     75 	 * only.
     76 	 *
     77 	 * TODO:
     78 	 * There is still "crypto: unable to register devsw, error 17" message.
     79 	 * it should be suppressed.
     80 	 */
     81 	rump_pdev_add(swcryptoattach, 0);
     82 #endif

This is all very grody and should be done differently, and it's not
clear that just suppressing the warning here is right.