[src/trunk]: src/external/cddl/osnet/dev/dtrace When loading the module, if d...

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

details:   https://anonhg.NetBSD.org/src/rev/96ddfc1c4f9f
branches:  trunk
changeset: 812054:96ddfc1c4f9f
user:      pgoyette <pgoyette%NetBSD.org@localhost>
date:      Sat Nov 28 22:41:36 2015 +0000

description:
When loading the module, if devsw_attach() fails, call dtrace_unload()
to undo the effects of dtrace_load().  And if dtrace_unload() fails,
panic (since we can't get the system back to its earlier stable state).

When unloading the module, call devsw_detach() first, to lock out any
new access.  Then call dtrace_unload().  If dgtrace_unload() fails,
reattach the devsw, and if that fails, panic.

Implements fixes described in PR kern/43032

diffstat:

 external/cddl/osnet/dev/dtrace/dtrace_modevent.c |  21 +++++++++++++++++----
 1 files changed, 17 insertions(+), 4 deletions(-)

diffs (39 lines):

diff -r f07374d25c5e -r 96ddfc1c4f9f external/cddl/osnet/dev/dtrace/dtrace_modevent.c
--- a/external/cddl/osnet/dev/dtrace/dtrace_modevent.c  Sat Nov 28 21:06:30 2015 +0000
+++ b/external/cddl/osnet/dev/dtrace/dtrace_modevent.c  Sat Nov 28 22:41:36 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dtrace_modevent.c,v 1.4 2015/02/26 09:10:52 ozaki-r Exp $      */
+/*     $NetBSD: dtrace_modevent.c,v 1.5 2015/11/28 22:41:36 pgoyette Exp $     */
 
 /*
  * CDDL HEADER START
@@ -34,13 +34,26 @@
        switch (cmd) {
        case MODULE_CMD_INIT:
                dtrace_load(NULL);
-               return devsw_attach("dtrace", NULL, &bmajor,
+               error = devsw_attach("dtrace", NULL, &bmajor,
                    &dtrace_cdevsw, &cmajor);
+               if (error != 0)
+                       if (dtrace_unload() != 0)
+                               panic("failed to unload dtrace");
+               return error;
+
        case MODULE_CMD_FINI:
-               error = dtrace_unload();
+               error = devsw_detach(NULL, &dtrace_cdevsw);
                if (error != 0)
                        return error;
-               return devsw_detach(NULL, &dtrace_cdevsw);
+
+               error = dtrace_unload();
+               if (error != 0) {
+                       if (devsw_attach("dtrace", NULL, &bmajor,
+                                        &dtrace_cdevsw, &cmajor) != 0)
+                               panic("failed to reattach dtrace_devsw");
+               }
+               return error;
+
        case MODULE_CMD_AUTOUNLOAD:
                return EBUSY;
        default: