openwrt-packages-dist/libs/db47/patches/003-dead_lock.patch

diff -urN db-4.7.25.NC/lock/lock_deadlock.c db-4.7.25.NC.new/lock/lock_deadlock.c
--- db-4.7.25.NC/lock/lock_deadlock.c	2008-03-10 14:31:33.000000000 +0100
+++ db-4.7.25.NC.new/lock/lock_deadlock.c	2009-11-08 12:53:25.000000000 +0100
@@ -121,7 +121,7 @@
 	DB_LOCKTAB *lt;
 	db_timespec now;
 	locker_info *idmap;
-	u_int32_t *bitmap, *copymap, **deadp, **free_me, *tmpmap;
+	u_int32_t *bitmap, *copymap, **deadp, **deadlist, *tmpmap;
 	u_int32_t i, cid, keeper, killid, limit, nalloc, nlockers;
 	u_int32_t lock_max, txn_max;
 	int ret, status;
@@ -133,7 +133,8 @@
 	if (IS_REP_CLIENT(env))
 		atype = DB_LOCK_MINWRITE;
 
-	free_me = NULL;
+	copymap = tmpmap = NULL;
+	deadlist = NULL;
 
 	lt = env->lk_handle;
 	if (rejectp != NULL)
@@ -179,11 +180,11 @@
 	memcpy(copymap, bitmap, nlockers * sizeof(u_int32_t) * nalloc);
 
 	if ((ret = __os_calloc(env, sizeof(u_int32_t), nalloc, &tmpmap)) != 0)
-		goto err1;
+		goto err;
 
 	/* Find a deadlock. */
 	if ((ret =
-	    __dd_find(env, bitmap, idmap, nlockers, nalloc, &deadp)) != 0)
+	    __dd_find(env, bitmap, idmap, nlockers, nalloc, &deadlist)) != 0)
 		return (ret);
 
 	/*
@@ -204,8 +205,7 @@
 		txn_max = TXN_MAXIMUM;
 
 	killid = BAD_KILLID;
-	free_me = deadp;
-	for (; *deadp != NULL; deadp++) {
+	for (deadp = deadlist; *deadp != NULL; deadp++) {
 		if (rejectp != NULL)
 			++*rejectp;
 		killid = (u_int32_t)(*deadp - bitmap) / nalloc;
@@ -342,11 +342,12 @@
 			__db_msg(env,
 			    "Aborting locker %lx", (u_long)idmap[killid].id);
 	}
-	__os_free(env, tmpmap);
-err1:	__os_free(env, copymap);
-
-err:	if (free_me != NULL)
-		__os_free(env, free_me);
+err:	if(copymap != NULL)
+		__os_free(env, copymap);
+	if (deadlist != NULL)
+		__os_free(env, deadlist);
+	if(tmpmap != NULL)
+		__os_free(env, tmpmap);
 	__os_free(env, bitmap);
 	__os_free(env, idmap);
 
@@ -360,6 +361,17 @@
 
 #define	DD_INVALID_ID	((u_int32_t) -1)
 
+/*
+ * __dd_build --
+ *	Build the lock dependency bit maps.
+ * Notes on syncronization:  
+ *	LOCK_SYSTEM_LOCK is used to hold objects locked when we have
+ *		a single partition.
+ *	LOCK_LOCKERS is held while we are walking the lockers list and
+ *		to single thread the use of lockerp->dd_id.
+ *	LOCK_DD protects the DD list of objects.
+ */
+
 static int
 __dd_build(env, atype, bmp, nlockers, allocp, idmap, rejectp)
 	ENV *env;
@@ -393,6 +405,7 @@
 	 * In particular we do not build the conflict array and our caller
 	 * needs to expect this.
 	 */
+	LOCK_SYSTEM_LOCK(lt, region);
 	if (atype == DB_LOCK_EXPIRE) {
 skip:		LOCK_DD(env, region);
 		op = SH_TAILQ_FIRST(&region->dd_objs, __db_lockobj);
@@ -430,17 +443,18 @@
 			OBJECT_UNLOCK(lt, region, indx);
 		}
 		UNLOCK_DD(env, region);
+		LOCK_SYSTEM_UNLOCK(lt, region);
 		goto done;
 	}
 
 	/*
-	 * We'll check how many lockers there are, add a few more in for
-	 * good measure and then allocate all the structures.  Then we'll
-	 * verify that we have enough room when we go back in and get the
-	 * mutex the second time.
+	 * Allocate after locking the region
+	 * to make sure the structures are large enough.
 	 */
-retry:	count = region->stat.st_nlockers;
+	LOCK_LOCKERS(env, region);
+	count = region->stat.st_nlockers;
 	if (count == 0) {
+		UNLOCK_LOCKERS(env, region);
 		*nlockers = 0;
 		return (0);
 	}
@@ -448,50 +462,37 @@
 	if (FLD_ISSET(env->dbenv->verbose, DB_VERB_DEADLOCK))
 		__db_msg(env, "%lu lockers", (u_long)count);
 
-	count += 20;
 	nentries = (u_int32_t)DB_ALIGN(count, 32) / 32;
 
-	/*
-	 * Allocate enough space for a count by count bitmap matrix.
-	 *
-	 * XXX
-	 * We can probably save the malloc's between iterations just
-	 * reallocing if necessary because count grew by too much.
-	 */
+	/* Allocate enough space for a count by count bitmap matrix. */
 	if ((ret = __os_calloc(env, (size_t)count,
-	    sizeof(u_int32_t) * nentries, &bitmap)) != 0)
+	    sizeof(u_int32_t) * nentries, &bitmap)) != 0) {
+		UNLOCK_LOCKERS(env, region);
 		return (ret);
+	}
 
 	if ((ret = __os_calloc(env,
 	    sizeof(u_int32_t), nentries, &tmpmap)) != 0) {
+		UNLOCK_LOCKERS(env, region);
 		__os_free(env, bitmap);
 		return (ret);
 	}
 
 	if ((ret = __os_calloc(env,
 	    (size_t)count, sizeof(locker_info), &id_array)) != 0) {
+		UNLOCK_LOCKERS(env, region);
 		__os_free(env, bitmap);
 		__os_free(env, tmpmap);
 		return (ret);
 	}
 
 	/*
-	 * Now go back in and actually fill in the matrix.
-	 */
-	if (region->stat.st_nlockers > count) {
-		__os_free(env, bitmap);
-		__os_free(env, tmpmap);
-		__os_free(env, id_array);
-		goto retry;
-	}
-
-	/*
 	 * First we go through and assign each locker a deadlock detector id.
 	 */
 	id = 0;
-	LOCK_LOCKERS(env, region);
 	SH_TAILQ_FOREACH(lip, &region->lockers, ulinks, __db_locker) {
 		if (lip->master_locker == INVALID_ROFF) {
+			DB_ASSERT(env, id < count);
 			lip->dd_id = id++;
 			id_array[lip->dd_id].id = lip->id;
 			switch (atype) {
@@ -510,7 +511,6 @@
 			lip->dd_id = DD_INVALID_ID;
 
 	}
-	UNLOCK_LOCKERS(env, region);
 
 	/*
 	 * We only need consider objects that have waiters, so we use
@@ -669,7 +669,6 @@
 	 * status after building the bit maps so that we will not detect
 	 * a blocked transaction without noting that it is already aborting.
 	 */
-	LOCK_LOCKERS(env, region);
 	for (id = 0; id < count; id++) {
 		if (!id_array[id].valid)
 			continue;
@@ -738,6 +737,7 @@
 			id_array[id].in_abort = 1;
 	}
 	UNLOCK_LOCKERS(env, region);
+	LOCK_SYSTEM_UNLOCK(lt, region);
 
 	/*
 	 * Now we can release everything except the bitmap matrix that we
@@ -839,6 +839,7 @@
 	ret = 0;
 
 	/* We must lock so this locker cannot go away while we abort it. */
+	LOCK_SYSTEM_LOCK(lt, region);
 	LOCK_LOCKERS(env, region);
 
 	/*
@@ -895,6 +896,7 @@
 done:	OBJECT_UNLOCK(lt, region, info->last_ndx);
 err:
 out:	UNLOCK_LOCKERS(env, region);
+	LOCK_SYSTEM_UNLOCK(lt, region);
 	return (ret);
 }