Don't release and acquire Giant in mi_switch(). Instead, release and

acquire Giant as needed in functions that call mi_switch().  The releases
need to be done outside of the sched_lock to avoid potential deadlocks
from trying to acquire Giant while interrupts are disabled.

Submitted by:	witness

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/kern/kern_subr.c b/sys/kern/kern_subr.c
index 7c5c94a..429f34b 100644
--- a/sys/kern/kern_subr.c
+++ b/sys/kern/kern_subr.c
@@ -377,11 +377,13 @@ uio_yield()
 
 	p = curproc;
 	s = splhigh();
+	DROP_GIANT_NOSWITCH();
 	mtx_enter(&sched_lock, MTX_SPIN);
 	p->p_priority = p->p_usrpri;
 	setrunqueue(p);
 	p->p_stats->p_ru.ru_nivcsw++;
 	mi_switch();
 	mtx_exit(&sched_lock, MTX_SPIN);
+	PICKUP_GIANT();
 	splx(s);
 }