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

[firefly-linux-kernel-4.4.55.git] / drivers / s390 / cio / qdio_main.c

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index e9fff2b9bce23e3d905968488d72138165e268fc..479c665e9e7c25f91996eeb287770384009c9b7a 100644 (file)
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -476,7 +476,7 @@ static inline void inbound_primed(struct qdio_q *q, int count)
 static int get_inbound_buffer_frontier(struct qdio_q *q)
 {
        int count, stop;
-       unsigned char state;
+       unsigned char state = 0;
 
        /*
         * Don't check 128 buffers, as otherwise qdio_inbound_q_moved
@@ -643,7 +643,7 @@ void qdio_inbound_processing(unsigned long data)
 static int get_outbound_buffer_frontier(struct qdio_q *q)
 {
        int count, stop;
-       unsigned char state;
+       unsigned char state = 0;
 
        if (need_siga_sync(q))
                if (((queue_type(q) != QDIO_IQDIO_QFMT) &&
@@ -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);