From 53f7a1a6a92772a333704dde2cbd1fa0fd958066 Mon Sep 17 00:00:00 2001
From: marko <Unknown>
Date: Wed, 13 Jan 2010 20:38:53 +0000
Subject: [PATCH] branches/zip: lock_rec_validate_page(): Only validate the
 record queues when the thread is not holding a space->latch.

When UNIV_DEBUG is defined while UNIV_SYNC_DEBUG is not,
latching order violations will still occur and deadlocks will be possible.

sync_thread_levels_nonempty_gen(): Renamed from
sync_thread_levels_empty_gen().  Return the violating latch or NULL
instead of FALSE or TRUE, except that there will be a ut_error before
the non-NULL return.

sync_thread_levels_empty_gen(): A macro that negates the return value of
sync_thread_levels_nonempty_gen().

sync_thread_levels_contains(): New function, based on
sync_thread_levels_nonempty_gen().

This should fix Issue #441.
---
 include/sync0sync.h | 21 ++++++++++----
 lock/lock0lock.c    |  7 +++++
 sync/sync0sync.c    | 68 +++++++++++++++++++++++++++++++++++++++------
 3 files changed, 82 insertions(+), 14 deletions(-)

diff --git a/include/sync0sync.h b/include/sync0sync.h
index df990823cc4..f8d86eb1c84 100644
--- a/include/sync0sync.h
+++ b/include/sync0sync.h
@@ -238,16 +238,27 @@ ibool
 sync_thread_levels_empty(void);
 /*==========================*/
 /******************************************************************//**
-Checks that the level array for the current thread is empty.
-@return	TRUE if empty except the exceptions specified below */
+Checks if the level array for the current thread contains a
+mutex or rw-latch at the specified level.
+@return	a matching latch, or NULL if not found */
 UNIV_INTERN
-ibool
-sync_thread_levels_empty_gen(
-/*=========================*/
+void*
+sync_thread_levels_contains(
+/*========================*/
+	ulint	level);			/*!< in: latching order level
+					(SYNC_DICT, ...)*/
+/******************************************************************//**
+Checks if the level array for the current thread is empty.
+@return	a latch, or NULL if empty except the exceptions specified below */
+UNIV_INTERN
+void*
+sync_thread_levels_nonempty_gen(
+/*============================*/
 	ibool	dict_mutex_allowed);	/*!< in: TRUE if dictionary mutex is
 					allowed to be owned by the thread,
 					also purge_is_running mutex is
 					allowed */
+#define sync_thread_levels_empty_gen(d) (!sync_thread_levels_nonempty_gen(d))
 /******************************************************************//**
 Gets the debug information for a reserved mutex. */
 UNIV_INTERN
diff --git a/lock/lock0lock.c b/lock/lock0lock.c
index 3db7c2b36bc..0fa67d31716 100644
--- a/lock/lock0lock.c
+++ b/lock/lock0lock.c
@@ -4766,6 +4766,13 @@ loop:
 	     || lock->trx->conc_state == TRX_PREPARED
 	     || lock->trx->conc_state == TRX_COMMITTED_IN_MEMORY);
 
+# ifdef UNIV_SYNC_DEBUG
+	/* Only validate the record queues when this thread is not
+	holding a space->latch.  Deadlocks are possible due to
+	latching order violation when UNIV_DEBUG is defined while
+	UNIV_SYNC_DEBUG is not. */
+	if (!sync_thread_levels_contains(SYNC_FSP))
+# endif /* UNIV_SYNC_DEBUG */
 	for (i = nth_bit; i < lock_rec_get_n_bits(lock); i++) {
 
 		if (i == 1 || lock_rec_get_nth_bit(lock, i)) {
diff --git a/sync/sync0sync.c b/sync/sync0sync.c
index f1527907ef6..669e0667485 100644
--- a/sync/sync0sync.c
+++ b/sync/sync0sync.c
@@ -958,12 +958,62 @@ sync_thread_levels_contain(
 }
 
 /******************************************************************//**
-Checks that the level array for the current thread is empty.
-@return	TRUE if empty except the exceptions specified below */
+Checks if the level array for the current thread contains a
+mutex or rw-latch at the specified level.
+@return	a matching latch, or NULL if not found */
 UNIV_INTERN
-ibool
-sync_thread_levels_empty_gen(
-/*=========================*/
+void*
+sync_thread_levels_contains(
+/*========================*/
+	ulint	level)			/*!< in: latching order level
+					(SYNC_DICT, ...)*/
+{
+	sync_level_t*	arr;
+	sync_thread_t*	thread_slot;
+	sync_level_t*	slot;
+	ulint		i;
+
+	if (!sync_order_checks_on) {
+
+		return(NULL);
+	}
+
+	mutex_enter(&sync_thread_mutex);
+
+	thread_slot = sync_thread_level_arrays_find_slot();
+
+	if (thread_slot == NULL) {
+
+		mutex_exit(&sync_thread_mutex);
+
+		return(NULL);
+	}
+
+	arr = thread_slot->levels;
+
+	for (i = 0; i < SYNC_THREAD_N_LEVELS; i++) {
+
+		slot = sync_thread_levels_get_nth(arr, i);
+
+		if (slot->latch != NULL && slot->level == level) {
+
+			mutex_exit(&sync_thread_mutex);
+			return(slot->latch);
+		}
+	}
+
+	mutex_exit(&sync_thread_mutex);
+
+	return(NULL);
+}
+
+/******************************************************************//**
+Checks that the level array for the current thread is empty.
+@return	a latch, or NULL if empty except the exceptions specified below */
+UNIV_INTERN
+void*
+sync_thread_levels_nonempty_gen(
+/*============================*/
 	ibool	dict_mutex_allowed)	/*!< in: TRUE if dictionary mutex is
 					allowed to be owned by the thread,
 					also purge_is_running mutex is
@@ -976,7 +1026,7 @@ sync_thread_levels_empty_gen(
 
 	if (!sync_order_checks_on) {
 
-		return(TRUE);
+		return(NULL);
 	}
 
 	mutex_enter(&sync_thread_mutex);
@@ -987,7 +1037,7 @@ sync_thread_levels_empty_gen(
 
 		mutex_exit(&sync_thread_mutex);
 
-		return(TRUE);
+		return(NULL);
 	}
 
 	arr = thread_slot->levels;
@@ -1004,13 +1054,13 @@ sync_thread_levels_empty_gen(
 			mutex_exit(&sync_thread_mutex);
 			ut_error;
 
-			return(FALSE);
+			return(slot->latch);
 		}
 	}
 
 	mutex_exit(&sync_thread_mutex);
 
-	return(TRUE);
+	return(NULL);
 }
 
 /******************************************************************//**