Add a new per-thread private flag: TDP_GEOM.

This flag gets set whenever the thread posts an event on the GEOM
event queue, and if the flag is set when the thread is prepared
to return to userland from the kernel, g_waitidle() will be called
to make sure that the posted events have completed.

This can replace an insufficient number of g_waitidle() calls in
various other places, and has the advantage of being failsafe:  Any
system call which does a VOP_OPEN()/VOP_CLOSE will now correctly
wait for any geom events it posted as part of spoils or tastes.

Assert that topology and Giant is not held in g_waitidle().

1 files changed, 7 insertions, 0 deletions

diff --git a/sys/kern/subr_trap.c b/sys/kern/subr_trap.c
index 86026a4..89fab49 100644
--- a/sys/kern/subr_trap.c
+++ b/sys/kern/subr_trap.c
@@ -95,6 +95,13 @@ userret(td, frame, oticks)
 #endif
 
 	/*
+	 * If this thread tickled GEOM, we need to wait for the giggling to
+	 * stop before we return to userland
+	 */
+	if (td->td_pflags & TDP_GEOM)
+		g_waitidle();
+
+	/*
 	 * Let the scheduler adjust our priority etc.
 	 */
 	sched_userret(td);