kfifo: fix warn_unused_result

Fix the "ignoring return value of '...', declared with attribute
warn_unused_result" compiler warning in several users of the new kfifo
API.

It removes the __must_check attribute from kfifo_in() and
kfifo_in_locked() which must not necessary performed.

Fix the allocation bug in the nozomi driver file, by moving out the
kfifo_alloc from the interrupt handler into the probe function.

Fix the kfifo_out() and kfifo_out_locked() users to handle a unexpected
end of fifo.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/nozomi.c b/drivers/char/nozomi.c
index 9ef2434..7d73cd4 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -685,8 +685,6 @@
 		dump_table(dc);
 
 		for (i = PORT_MDM; i < MAX_PORT; i++) {
-			kfifo_alloc(&dc->port[i].fifo_ul,
-				FIFO_BUFFER_SIZE_UL, GFP_ATOMIC);
 			memset(&dc->port[i].ctrl_dl, 0, sizeof(struct ctrl_dl));
 			memset(&dc->port[i].ctrl_ul, 0, sizeof(struct ctrl_ul));
 		}
@@ -1433,6 +1431,16 @@
 		goto err_free_sbuf;
 	}
 
+	for (i = PORT_MDM; i < MAX_PORT; i++) {
+		if (kfifo_alloc(&dc->port[i].fifo_ul,
+		      FIFO_BUFFER_SIZE_UL, GFP_ATOMIC)) {
+			dev_err(&pdev->dev,
+					"Could not allocate kfifo buffer\n");
+			ret = -ENOMEM;
+			goto err_free_kfifo;
+		}
+	}
+
 	spin_lock_init(&dc->spin_mutex);
 
 	nozomi_setup_private_data(dc);
@@ -1445,7 +1453,7 @@
 			NOZOMI_NAME, dc);
 	if (unlikely(ret)) {
 		dev_err(&pdev->dev, "can't request irq %d\n", pdev->irq);
-		goto err_free_sbuf;
+		goto err_free_kfifo;
 	}
 
 	DBG1("base_addr: %p", dc->base_addr);
@@ -1464,13 +1472,28 @@
 	dc->state = NOZOMI_STATE_ENABLED;
 
 	for (i = 0; i < MAX_PORT; i++) {
+		struct device *tty_dev;
+
 		mutex_init(&dc->port[i].tty_sem);
 		tty_port_init(&dc->port[i].port);
-		tty_register_device(ntty_driver, dc->index_start + i,
+		tty_dev = tty_register_device(ntty_driver, dc->index_start + i,
 							&pdev->dev);
+
+		if (IS_ERR(tty_dev)) {
+			ret = PTR_ERR(tty_dev);
+			dev_err(&pdev->dev, "Could not allocate tty?\n");
+			goto err_free_tty;
+		}
 	}
+
 	return 0;
 
+err_free_tty:
+	for (i = dc->index_start; i < dc->index_start + MAX_PORT; ++i)
+		tty_unregister_device(ntty_driver, i);
+err_free_kfifo:
+	for (i = 0; i < MAX_PORT; i++)
+		kfifo_free(&dc->port[i].fifo_ul);
 err_free_sbuf:
 	kfree(dc->send_buf);
 	iounmap(dc->base_addr);