From: Jan Glauber <jang@linux.vnet.ibm.com>
Date: Wed, 23 Mar 2011 09:16:01 +0000 (+0100)
Subject: [S390] qdio: prevent handling of buffers if count is zero
X-Git-Tag: v2.6.39-rc1~67^2~5
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9a26513eb67ec4b2cb1744834076afad21b68aac;p=karo-tx-linux.git

[S390] qdio: prevent handling of buffers if count is zero

Exit do_QDIO early if the buffer count is zero to prevent side effects
in the following functions.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 5640c89cd9de..479c665e9e7c 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -1508,7 +1508,8 @@ int do_QDIO(struct ccw_device *cdev, unsigned int callflags,
 
 	if (irq_ptr->state != QDIO_IRQ_STATE_ACTIVE)
 		return -EBUSY;
-
+	if (!count)
+		return 0;
 	if (callflags & QDIO_FLAG_SYNC_INPUT)
 		return handle_inbound(irq_ptr->input_qs[q_nr],
 				      callflags, bufnr, count);