1 files changed, 5 insertions, 2 deletions

diff --git a/sys/kern/subr_sleepqueue.c b/sys/kern/subr_sleepqueue.c
index ac53fce06989..5e99d2218480 100644
--- a/sys/kern/subr_sleepqueue.c
+++ b/sys/kern/subr_sleepqueue.c
@@ -403,12 +403,15 @@ sleepq_catch_signals(void *wchan)
 		mtx_unlock(&ps->ps_mtx);
 	}
 	/*
-	 * Lock sleepq chain before unlocking proc
-	 * without this, we could lose a race.
+	 * Lock the per-process spinlock prior to dropping the PROC_LOCK
+	 * to avoid a signal delivery race.  PROC_LOCK, PROC_SLOCK, and
+	 * thread_lock() are currently held in tdsignal().
 	 */
+	PROC_SLOCK(p);
 	mtx_lock_spin(&sc->sc_lock);
 	PROC_UNLOCK(p);
 	thread_lock(td);
+	PROC_SUNLOCK(p);
 	if (ret == 0) {
 		if (!(td->td_flags & TDF_INTERRUPT)) {
 			sleepq_switch(wchan);