dmaengine: idxd: sysfs input of wq incorrect wq type should return error

Currently when inputing an unrecognized wq type, we set the wq type to
"none". It really should return error and not change the existing wq type
that's in the kernel.

Fixes: c52ca478 ("dmaengine: idxd: add configuration component of driver")
Reported-by: Yixin Zhang <yixin.zhang@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/158213304803.2290.13336343633425868211.stgit@djiang5-desk3.ch.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/idxd/sysfs.c

@@ -1002,12 +1002,14 @@ static ssize_t wq_type_store(struct device *dev,
 		return -EPERM;
 
 	old_type = wq->type;
-	if (sysfs_streq(buf, idxd_wq_type_names[IDXD_WQT_KERNEL]))
+	if (sysfs_streq(buf, idxd_wq_type_names[IDXD_WQT_NONE]))
+		wq->type = IDXD_WQT_NONE;
+	else if (sysfs_streq(buf, idxd_wq_type_names[IDXD_WQT_KERNEL]))
 		wq->type = IDXD_WQT_KERNEL;
 	else if (sysfs_streq(buf, idxd_wq_type_names[IDXD_WQT_USER]))
 		wq->type = IDXD_WQT_USER;
 	else
-		wq->type = IDXD_WQT_NONE;
+		return -EINVAL;
 
 	/* If we are changing queue type, clear the name */
 	if (wq->type != old_type)