Fixup r218424: uio_yield() was scaling directly to userland priority.

When kern_yield() was introduced with the possibility to specify
a new priority, the behaviour changed by not lowering priority at all
in the consumers, making the yielding mechanism highly ineffective for
high priority kthreads like bufdaemon, syncer, vlrudaemon, etc.
There are no evidences that consumers could bear with such change in
semantic and this situation could finally lead to bugs similar to the
ones fixed in r244240.
Re-specify userland pri for kthreads involved.

Tested by:	pho
Reviewed by:	kib, mdf
MFC after:	1 week

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
index 55f9468..4ee16ab 100644
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -1569,7 +1569,7 @@ softdep_process_worklist(mp, full)
 		 */
 		if (should_yield()) {
 			FREE_LOCK(&lk);
-			kern_yield(PRI_UNCHANGED);
+			kern_yield(PRI_USER);
 			bwillwrite();
 			ACQUIRE_LOCK(&lk);
 		}