r10492: work around a bug in solaris which cases lock upgrades to fail with

EDEADLK even when progress can be made. This is not a good solution,
but I can't find anything better.
(This used to be commit 980dd17f7d0a622cd772afc9ba15e50007ad9c6e)

3 files changed, 28 insertions, 1 deletions

diff --git a/source4/lib/tdb/common/lock.c b/source4/lib/tdb/common/lock.c
index 703cfe9dc5..04135a2274 100644
--- a/source4/lib/tdb/common/lock.c
+++ b/source4/lib/tdb/common/lock.c
@@ -81,6 +81,32 @@ int tdb_brlock_len(struct tdb_context *tdb, tdb_off_t offset,
 }
 
 
+/*
+  upgrade a read lock to a write lock. This needs to be handled in a
+  special way as some OSes (such as solaris) have too conservative
+  deadlock detection and claim a deadlock when progress can be
+  made. For those OSes we may loop for a while.  
+*/
+int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len)
+{
+	int count = 1000;
+	while (count--) {
+		struct timeval tv;
+		if (tdb_brlock_len(tdb, offset, F_WRLCK, F_SETLKW, 1, len) == 0) {
+			return 0;
+		}
+		if (errno != EDEADLK) {
+			break;
+		}
+		/* sleep for as short a time as we can - more portable than usleep() */
+		tv.tv_sec = 0;
+		tv.tv_usec = 1;
+		select(0, NULL, NULL, NULL, &tv);
+	}
+	return -1;
+}
+
+
 /* a byte range locking function - return 0 on success
    this functions locks/unlocks 1 byte at the specified offset.
 
diff --git a/source4/lib/tdb/common/tdb_private.h b/source4/lib/tdb/common/tdb_private.h
index d7471537d8..ce105a2a56 100644
--- a/source4/lib/tdb/common/tdb_private.h
+++ b/source4/lib/tdb/common/tdb_private.h
@@ -216,6 +216,7 @@ void tdb_mmap(struct tdb_context *tdb);
 int tdb_lock(struct tdb_context *tdb, int list, int ltype);
 int tdb_unlock(struct tdb_context *tdb, int list, int ltype);
 int tdb_brlock(struct tdb_context *tdb, tdb_off_t offset, int rw_type, int lck_type, int probe);
+int tdb_brlock_upgrade(struct tdb_context *tdb, tdb_off_t offset, size_t len);
 int tdb_brlock_len(struct tdb_context *tdb, tdb_off_t offset, 
 		   int rw_type, int lck_type, int probe, size_t len);
 int tdb_write_lock_record(struct tdb_context *tdb, tdb_off_t off);
diff --git a/source4/lib/tdb/common/transaction.c b/source4/lib/tdb/common/transaction.c
index cf0f378dce..9d37046116 100644
--- a/source4/lib/tdb/common/transaction.c
+++ b/source4/lib/tdb/common/transaction.c
@@ -772,7 +772,7 @@ int tdb_transaction_commit(struct tdb_context *tdb)
 	}
 
 	/* upgrade the main transaction lock region to a write lock */
-	if (tdb_brlock_len(tdb, FREELIST_TOP, F_WRLCK, F_SETLKW, 0, 0) == -1) {
+	if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
 		TDB_LOG((tdb, 0, "tdb_transaction_start: failed to upgrade hash locks\n"));
 		tdb->ecode = TDB_ERR_LOCK;
 		tdb_transaction_cancel(tdb);