From 01672f8c3a3fd28ea54576da47af9f0521fd01f3 Mon Sep 17 00:00:00 2001
From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Sun, 1 Jan 2012 15:08:37 -0800
Subject: [PATCH] vkernel - Unbreak 32-bit vkernel builds by fixing broken
 assertion

* [ASSERT_]MP_LOCK_HELD() was not properly handling the new token
  t_count format.

* Rename and document the functions a bit better.  Currently our
  more expansive token test for (shared or exclusive) is not
  a perfect test because we don't want to eat cpu time iterating
  the thread's token array to check for shared tokens.  So we just
  check for a shared count.

  Works well for assertions, wouldn't work very well for conditional
  acquisition (of a shared token).

* Exclusive token tests are perfect.

Reported-by: tuxillo
---
 sys/sys/mplock2.h |    4 ++--
 sys/sys/thread.h  |   10 +++++++---
 sys/sys/thread2.h |   26 +++++++++++++++++++++++---
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/sys/sys/mplock2.h b/sys/sys/mplock2.h
index 7a1a7ad..1e13c15 100644
--- a/sys/sys/mplock2.h
+++ b/sys/sys/mplock2.h
@@ -26,8 +26,8 @@
 
 void cpu_get_initial_mplock(void);
 
-#define MP_LOCK_HELD()		LWKT_TOKEN_HELD(&mp_token)
-#define ASSERT_MP_LOCK_HELD()	ASSERT_LWKT_TOKEN_HELD(&mp_token)
+#define MP_LOCK_HELD()		LWKT_TOKEN_HELD_EXCL(&mp_token)
+#define ASSERT_MP_LOCK_HELD()	ASSERT_LWKT_TOKEN_HELD_EXCL(&mp_token)
 
 #else
 
diff --git a/sys/sys/thread.h b/sys/sys/thread.h
index b4cc199..0d9c444 100644
--- a/sys/sys/thread.h
+++ b/sys/sys/thread.h
@@ -137,10 +137,14 @@ typedef struct lwkt_token {
 /*
  * Assert that a particular token is held
  */
-#define LWKT_TOKEN_HELD(tok)		_lwkt_token_held(tok, curthread)
+#define LWKT_TOKEN_HELD_ANY(tok)	_lwkt_token_held_any(tok, curthread)
+#define LWKT_TOKEN_HELD_EXCL(tok)	_lwkt_token_held_excl(tok, curthread)
 
-#define ASSERT_LWKT_TOKEN_HELD(tok)	\
-	KKASSERT(LWKT_TOKEN_HELD(tok))
+#define ASSERT_LWKT_TOKEN_HELD(tok)		\
+	KKASSERT(LWKT_TOKEN_HELD_ANY(tok))
+
+#define ASSERT_LWKT_TOKEN_HELD_EXCL(tok)	\
+	KKASSERT(LWKT_TOKEN_HELD_EXCL(tok))
 
 #define ASSERT_NO_TOKENS_HELD(td)	\
 	KKASSERT((td)->td_toks_stop == &td->td_toks_array[0])
diff --git a/sys/sys/thread2.h b/sys/sys/thread2.h
index acf848f..13bbff0 100644
--- a/sys/sys/thread2.h
+++ b/sys/sys/thread2.h
@@ -30,13 +30,33 @@
 #include <machine/cpufunc.h>
 
 /*
+ * Is a token held either by the specified thread or held shared?
+ *
+ * We can't inexpensively validate the thread for a shared token
+ * without iterating td->td_toks, so this isn't a perfect test.
+ */
+static __inline int
+_lwkt_token_held_any(lwkt_token_t tok, thread_t td)
+{
+	long count = tok->t_count;
+
+	cpu_ccfence();
+	if (tok->t_ref >= &td->td_toks_base && tok->t_ref < td->td_toks_stop)
+		return TRUE;
+	if ((count & TOK_EXCLUSIVE) == 0 &&
+	    (count & ~(TOK_EXCLUSIVE|TOK_EXCLREQ))) {
+		return TRUE;
+	}
+	return FALSE;
+}
+
+/*
  * Is a token held by the specified thread?
  */
 static __inline int
-_lwkt_token_held(lwkt_token_t tok, thread_t td)
+_lwkt_token_held_excl(lwkt_token_t tok, thread_t td)
 {
-	return ((tok->t_count & ~(TOK_EXCLUSIVE|TOK_EXCLREQ)) ||
-		(tok->t_ref >= &td->td_toks_base &&
+	return ((tok->t_ref >= &td->td_toks_base &&
 		 tok->t_ref < td->td_toks_stop));
 }
 
-- 
1.7.7.2