[src/trunk]: src/sys/opencrypto Implement in-module ref-counting, and do not ...

[pgoyette <pgoyette%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/92996573e5f8
branches:  trunk
changeset: 326180:92996573e5f8
user:      pgoyette <pgoyette%NetBSD.org@localhost>
date:      Tue Jan 21 20:33:01 2014 +0000

description:
Implement in-module ref-counting, and do not allow auto-unload if there
are existing references.

Note that manual unloading is not prevented.

OK christos@

XXX Also note that there is still a small window where the ref-count can
XXX be decremented, and then the process/thread preempted.  If auto-unload
XXX happens before that thread can return from the module's code, bad
XXX things (tm) could happen.

diffstat:

 sys/opencrypto/cryptodev.c |  20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)

diffs (79 lines):

diff -r 1acf90df58f8 -r 92996573e5f8 sys/opencrypto/cryptodev.c
--- a/sys/opencrypto/cryptodev.c        Tue Jan 21 20:24:29 2014 +0000
+++ b/sys/opencrypto/cryptodev.c        Tue Jan 21 20:33:01 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cryptodev.c,v 1.73 2014/01/21 18:54:28 pgoyette Exp $ */
+/*     $NetBSD: cryptodev.c,v 1.74 2014/01/21 20:33:01 pgoyette Exp $ */
 /*     $FreeBSD: src/sys/opencrypto/cryptodev.c,v 1.4.2.4 2003/06/03 00:09:02 sam Exp $        */
 /*     $OpenBSD: cryptodev.c,v 1.53 2002/07/10 22:21:30 mickey Exp $   */
 
@@ -64,7 +64,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cryptodev.c,v 1.73 2014/01/21 18:54:28 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cryptodev.c,v 1.74 2014/01/21 20:33:01 pgoyette Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -143,6 +143,8 @@
 static int     cryptowrite(dev_t dev, struct uio *uio, int ioflag);
 static int     cryptoselect(dev_t dev, int rw, struct lwp *l);
 
+static int     crypto_refcount = 0;    /* Prevent detaching while in use */
+
 /* Declaration of cloned-device (per-ctxt) entrypoints */
 static int     cryptof_read(struct file *, off_t *, struct uio *,
     kauth_cred_t, int);
@@ -262,6 +264,7 @@
                  */
                criofcr->sesn = 1;
                criofcr->requestid = 1;
+               crypto_refcount++;
                mutex_exit(&crypto_mtx);
                (void)fd_clone(criofp, criofd, (FREAD|FWRITE),
                              &cryptofops, criofcr);
@@ -951,6 +954,7 @@
        }
        seldestroy(&fcr->sinfo);
        fp->f_data = NULL;
+       crypto_refcount--;
        mutex_exit(&crypto_mtx);
 
        pool_put(&fcrpl, fcr);
@@ -1080,6 +1084,7 @@
         */
        fcr->sesn = 1;
        fcr->requestid = 1;
+       crypto_refcount++;
        mutex_exit(&crypto_mtx);
        return fd_clone(fp, fd, flag, &cryptofops, fcr);
 }
@@ -2206,8 +2211,6 @@
                return error;
        case MODULE_CMD_FINI:
 #ifdef _MODULE
-#ifdef notyet
-               /* We need to keep track of open instances before we do this */
                error = config_cfdata_detach(crypto_cfdata);
                if (error) {
                        return error;
@@ -2216,12 +2219,15 @@
                config_cfattach_detach(crypto_cd.cd_name, &crypto_ca);
                config_cfdriver_detach(&crypto_cd);
                devsw_detach(NULL, &crypto_cdevsw);
-#else
-               return EOPNOTSUPP;
-#endif
 #endif
 
                return error;
+#ifdef _MODULE
+       case MODULE_CMD_AUTOUNLOAD:
+               if (crypto_refcount != 0)
+                       return EBUSY;
+       /* FALLTHROUGH */
+#endif
        default:
                return ENOTTY;
        }