- Add an assertion to panic if one tries to call mtx_trylock() on a spin

  mutex.
- Don't panic if a spin lock is held too long inside _mtx_lock_spin() if
  panicstr is set (meaning that we are already in a panic).  Just keep
  spinning forever instead.

1 files changed, 4 insertions, 1 deletions

diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c
index c659fed..a0127e7 100644
--- a/sys/kern/kern_mutex.c
+++ b/sys/kern/kern_mutex.c
@@ -407,6 +407,9 @@ _mtx_trylock(struct mtx *m, int opts, const char *file, int line)
 	int rval;
 
 	MPASS(curthread != NULL);
+	KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
+	    ("mtx_trylock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
+	    file, line));
 
 	if (mtx_owned(m) && (m->mtx_object.lo_flags & LO_RECURSABLE) != 0) {
 		m->mtx_recurse++;
@@ -594,7 +597,7 @@ _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file,
 			}
 			if (i < 60000000)
 				DELAY(1);
-			else if (!kdb_active) {
+			else if (!kdb_active && !panicstr) {
 				printf("spin lock %s held by %p for > 5 seconds\n",
 				    m->mtx_object.lo_name, (void *)m->mtx_lock);
 #ifdef WITNESS