From: Venkatesh Srinivas <me@endeavour.zapto.org>
Date: Thu, 21 Apr 2011 20:46:39 +0000 (-0700)
Subject: kernel -- Slight changes to refcount_wait/_wakeup.
X-Git-Tag: v2.12.0~774
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/ed2fb120da2038d13bb9f0aebfba177ee57b1e4d?ds=sidebyside

kernel -- Slight changes to refcount_wait/_wakeup.

* Pass waitstring into refcount_wait.

* Record long waits in kernel log.
---

diff --git a/sys/kern/kern_refcount.c b/sys/kern/kern_refcount.c
index a34c8eced4..86ba884c45 100644
--- a/sys/kern/kern_refcount.c
+++ b/sys/kern/kern_refcount.c
@@ -62,18 +62,25 @@
  * up waiters.
  */
 void
-_refcount_wait(volatile u_int *countp)
+_refcount_wait(volatile u_int *countp, const char *wstr)
 {
 	u_int n;
+	int loops = 0;
+	int threshold = 5;
 
 	for (;;) {
 		n = *countp;
 		if (n == 0)
 			break;
+		if (loops > threshold) {
+			kprintf("refcount_wait %s long wait\n", wstr);
+			loops = 0;
+		}
 		KKASSERT(n != REFCNTF_WAITING);	/* impossible state */
 		tsleep_interlock(countp, 0);
 		if (atomic_cmpset_int(countp, n, n | REFCNTF_WAITING))
-			tsleep(countp, PINTERLOCKED, "refwait", 0);
+			tsleep(countp, PINTERLOCKED, wstr, hz*10);
+		loops++;
 	}
 }
 
diff --git a/sys/sys/refcount.h b/sys/sys/refcount.h
index 6065327695..c12ab67aad 100644
--- a/sys/sys/refcount.h
+++ b/sys/sys/refcount.h
@@ -37,7 +37,7 @@
 
 #define REFCNTF_WAITING	0x40000000
 
-void _refcount_wait(volatile u_int *countp);
+void _refcount_wait(volatile u_int *countp, const char *wstr);
 int _refcount_release_wakeup(volatile u_int *countp);
 
 static __inline void
@@ -83,10 +83,10 @@ refcount_release_wakeup(volatile u_int *countp)
  *	     use refcount_release_wakeup() instead of refcount_release().
  */
 static __inline void
-refcount_wait(volatile u_int *countp)
+refcount_wait(volatile u_int *countp, const char *wstr)
 {
 	if (*countp)
-		_refcount_wait(countp);
+		_refcount_wait(countp, wstr);
 }
 
 #endif	/* ! __SYS_REFCOUNT_H__ */