1 files changed, 64 insertions, 2 deletions

diff --git a/sys/kern/subr_sleepqueue.c b/sys/kern/subr_sleepqueue.c
index 8443a7ffeaf2..378fc691eade 100644
--- a/sys/kern/subr_sleepqueue.c
+++ b/sys/kern/subr_sleepqueue.c
@@ -59,11 +59,12 @@
  * variables.
  */
 
-#include "opt_sleepqueue_profiling.h"
-
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include "opt_sleepqueue_profiling.h"
+#include "opt_ddb.h"
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/lock.h>
@@ -77,6 +78,10 @@ __FBSDID("$FreeBSD$");
 #include <sys/sleepqueue.h>
 #include <sys/sysctl.h>
 
+#ifdef DDB
+#include <ddb/ddb.h>
+#endif
+
 /*
  * Constants for the hash table of sleep queue chains.  These constants are
  * the same ones that 4BSD (and possibly earlier versions of BSD) used.
@@ -842,3 +847,60 @@ sleepq_abort(struct thread *td)
 	sleepq_remove(td, wchan);
 	mtx_lock_spin(&sched_lock);
 }
+
+#ifdef DDB
+DB_SHOW_COMMAND(sleepq, db_show_sleepqueue)
+{
+	struct sleepqueue_chain *sc;
+	struct sleepqueue *sq;
+	struct lock_object *lock;
+	struct thread *td;
+	void *wchan;
+	int i;
+
+	if (!have_addr)
+		return;
+
+	/*
+	 * First, see if there is an active sleep queue for the wait channel
+	 * indicated by the address.
+	 */
+	wchan = (void *)addr;
+	sc = SC_LOOKUP(wchan);
+	LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
+		if (sq->sq_wchan == wchan)
+			goto found;
+
+	/*
+	 * Second, see if there is an active sleep queue at the address
+	 * indicated.
+	 */
+	for (i = 0; i < SC_TABLESIZE; i++)
+		LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) {
+			if (sq == (struct sleepqueue *)addr)
+				goto found;
+		}
+
+	db_printf("Unable to locate a sleep queue via %p\n", (void *)addr);
+	return;
+found:
+	db_printf("Wait channel: %p\n", sq->sq_wchan);
+#ifdef INVARIANTS
+	db_printf("Queue type: %d\n", sq->sq_type);
+	if (sq->sq_lock) {
+		lock = &sq->sq_lock->mtx_object;
+		db_printf("Associated Interlock: %p - (%s) %s\n", lock,
+		    LOCK_CLASS(lock)->lc_name, lock->lo_name);
+	}
+#endif
+	db_printf("Blocked threads:\n");
+	if (TAILQ_EMPTY(&sq->sq_blocked))
+		db_printf("\tempty\n");
+	else
+		TAILQ_FOREACH(td, &sq->sq_blocked, td_slpq) {
+			db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td,
+			    td->td_tid, td->td_proc->p_pid,
+			    td->td_proc->p_comm);
+		}	
+}
+#endif