stable/11 debugging kernel unable to produce crashdump again

[Mark Johnston]

On Tue, Jul 25, 2017 at 12:03:05AM +0700, Eugene Grosbein wrote:
> Thanks, this helped:
> 
> $ addr2line -f -e kernel.debug 0xffffffff80919c00
> g_raid_shutdown_post_sync
> /home/src/sys/geom/raid/g_raid.c:2458
> 
> That is GEOM_RAID's g_raid_shutdown_post_sync() that hangs if called just before
> crashdump generation but works just fine during normal system shutdown.

I think graid probably needs a treatment similar to r301173/r316032.
g_raid_shutdown_post_sync() appears to be quite similar to the
corresponding gmirror handler. In particular, it just attempts to mark
the individual components as clean and destroy the GEOM, which is not
really safe after a panic.

diff --git a/sys/geom/raid/g_raid.c b/sys/geom/raid/g_raid.c
index 7a1fd8c5ce2e..aa2529d5466a 100644
--- a/sys/geom/raid/g_raid.c
+++ b/sys/geom/raid/g_raid.c
@@ -2461,6 +2461,9 @@ g_raid_shutdown_post_sync(void *arg, int howto)
 	struct g_raid_softc *sc;
 	struct g_raid_volume *vol;
 
+	if (panicstr != NULL)
+		return;
+
 	mp = arg;
 	g_topology_lock();
 	g_raid_shutdown = 1;