WT-2698 Change flag into atomically manipulated field to avoid deadlock. (#2796)

3 files changed, 24 insertions, 16 deletions

diff --git a/src/conn/conn_dhandle.c b/src/conn/conn_dhandle.c
index 9c376d1c320..08fb2b24468 100644
--- a/src/conn/conn_dhandle.c
+++ b/src/conn/conn_dhandle.c
@@ -544,6 +544,7 @@ __wt_conn_dhandle_discard_single(
 	WT_DATA_HANDLE *dhandle;
 	WT_DECL_RET;
 	int tret;
+	bool set_pass_intr;
 
 	dhandle = session->dhandle;
 
@@ -562,13 +563,17 @@ __wt_conn_dhandle_discard_single(
 	 * Kludge: interrupt the eviction server in case it is holding the
 	 * handle list lock.
 	 */
-	if (!F_ISSET(session, WT_SESSION_LOCKED_HANDLE_LIST))
-		F_SET(S2C(session)->cache, WT_CACHE_PASS_INTERRUPT);
+	set_pass_intr = false;
+	if (!F_ISSET(session, WT_SESSION_LOCKED_HANDLE_LIST)) {
+		set_pass_intr = true;
+		(void)__wt_atomic_add32(&S2C(session)->cache->pass_intr, 1);
+	}
 
 	/* Try to remove the handle, protected by the data handle lock. */
 	WT_WITH_HANDLE_LIST_LOCK(session,
 	    tret = __conn_dhandle_remove(session, final));
-	F_CLR(S2C(session)->cache, WT_CACHE_PASS_INTERRUPT);
+	if (set_pass_intr)
+		(void)__wt_atomic_sub32(&S2C(session)->cache->pass_intr, 1);
 	WT_TRET(tret);
 
 	/*
diff --git a/src/evict/evict_lru.c b/src/evict/evict_lru.c
index 382d6ee1653..b6a3d114380 100644
--- a/src/evict/evict_lru.c
+++ b/src/evict/evict_lru.c
@@ -273,7 +273,7 @@ __evict_server(WT_SESSION_IMPL *session, bool *did_work)
 	if (!F_ISSET(cache, WT_CACHE_STUCK)) {
 		for (spins = 0; (ret = __wt_spin_trylock(
 		    session, &conn->dhandle_lock)) == EBUSY &&
-		    !F_ISSET(cache, WT_CACHE_PASS_INTERRUPT); spins++) {
+		    cache->pass_intr == 0; spins++) {
 			if (spins < WT_THOUSAND)
 				__wt_yield();
 			else
@@ -610,7 +610,7 @@ __evict_pass(WT_SESSION_IMPL *session)
 		 * If there is a request to clear eviction walks, do that now,
 		 * before checking if the cache is full.
 		 */
-		if (F_ISSET(cache, WT_CACHE_PASS_INTERRUPT))
+		if (cache->pass_intr != 0)
 			break;
 
 		/*
@@ -797,13 +797,13 @@ __wt_evict_file_exclusive_on(WT_SESSION_IMPL *session)
 	 * this point.
 	 */
 	F_SET(btree, WT_BTREE_NO_EVICTION);
-	F_SET(cache, WT_CACHE_PASS_INTERRUPT);
+	(void)__wt_atomic_add32(&cache->pass_intr, 1);
 	WT_FULL_BARRIER();
 
 	/* Clear any existing LRU eviction walk for the file. */
 	WT_WITH_PASS_LOCK(session, ret,
 	    ret = __evict_clear_walk(session));
-	F_CLR(cache, WT_CACHE_PASS_INTERRUPT);
+	(void)__wt_atomic_sub32(&cache->pass_intr, 1);
 	WT_ERR(ret);
 
 	/*
@@ -1087,7 +1087,7 @@ retry:	while (slot < max_entries && ret == 0) {
 		 * If another thread is waiting on the eviction server to clear
 		 * the walk point in a tree, give up.
 		 */
-		if (F_ISSET(cache, WT_CACHE_PASS_INTERRUPT))
+		if (cache->pass_intr != 0)
 			break;
 
 		/*
@@ -1097,7 +1097,7 @@ retry:	while (slot < max_entries && ret == 0) {
 		if (!dhandle_locked) {
 			for (spins = 0; (ret = __wt_spin_trylock(
 			    session, &conn->dhandle_lock)) == EBUSY &&
-			    !F_ISSET(cache, WT_CACHE_PASS_INTERRUPT);
+			    cache->pass_intr == 0;
 			    spins++) {
 				if (spins < WT_THOUSAND)
 					__wt_yield();
@@ -1223,7 +1223,7 @@ retry:	while (slot < max_entries && ret == 0) {
 	 * Try two passes through all the files, give up when we have some
 	 * candidates and we aren't finding more.
 	 */
-	if (!F_ISSET(cache, WT_CACHE_PASS_INTERRUPT) && ret == 0 &&
+	if (cache->pass_intr == 0 && ret == 0 &&
 	    slot < max_entries && (retries < 2 ||
 	    (retries < 10 &&
 	    !FLD_ISSET(cache->state, WT_EVICT_PASS_WOULD_BLOCK) &&
diff --git a/src/include/cache.h b/src/include/cache.h
index 411aebacad7..24e12f5af63 100644
--- a/src/include/cache.h
+++ b/src/include/cache.h
@@ -149,16 +149,19 @@ struct __wt_cache {
 #define	WT_EVICT_PASS_DIRTY		0x04
 #define	WT_EVICT_PASS_WOULD_BLOCK	0x08
 	uint32_t state;
+	/*
+	 * Pass interrupt counter.
+	 */
+	uint32_t pass_intr;		/* Interrupt eviction pass. */
 
 	/*
 	 * Flags.
 	 */
-#define	WT_CACHE_PASS_INTERRUPT	0x01	/* Stop eviction walks */
-#define	WT_CACHE_POOL_MANAGER	0x02	/* The active cache pool manager */
-#define	WT_CACHE_POOL_RUN	0x04	/* Cache pool thread running */
-#define	WT_CACHE_STUCK		0x08	/* Eviction server is stuck */
-#define	WT_CACHE_WALK_REVERSE	0x10	/* Scan backwards for candidates */
-#define	WT_CACHE_WOULD_BLOCK	0x20	/* Pages that would block apps */
+#define	WT_CACHE_POOL_MANAGER	0x01	/* The active cache pool manager */
+#define	WT_CACHE_POOL_RUN	0x02	/* Cache pool thread running */
+#define	WT_CACHE_STUCK		0x04	/* Eviction server is stuck */
+#define	WT_CACHE_WALK_REVERSE	0x08	/* Scan backwards for candidates */
+#define	WT_CACHE_WOULD_BLOCK	0x10	/* Pages that would block apps */
 	uint32_t flags;
 };