hvsi: don't panic on tty_register_driver failure

[ Upstream commit 7ccbdcc ]

The alloc_tty_driver failure is handled gracefully in hvsi_init. But
tty_register_driver is not. panic is called if that one fails.

So handle the failure of tty_register_driver gracefully too. This will
keep at least the console functional as it was enabled earlier by
console_initcall in hvsi_console_init. Instead of shooting down the
whole system.

This means, we disable interrupts and restore hvsi_wait back to
poll_for_state().

Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210723074317.32690-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/tty/hvc/hvsi.c

@@ -1038,7 +1038,7 @@ static const struct tty_operations hvsi_ops = {
 
 static int __init hvsi_init(void)
 {
-	int i;
+	int i, ret;
 
 	hvsi_driver = alloc_tty_driver(hvsi_count);
 	if (!hvsi_driver)
@@ -1069,12 +1069,25 @@ static int __init hvsi_init(void)
 	}
 	hvsi_wait = wait_for_state; /* irqs active now */
 
-	if (tty_register_driver(hvsi_driver))
-		panic("Couldn't register hvsi console driver\n");
+	ret = tty_register_driver(hvsi_driver);
+	if (ret) {
+		pr_err("Couldn't register hvsi console driver\n");
+		goto err_free_irq;
+	}
 
 	printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
 
 	return 0;
+err_free_irq:
+	hvsi_wait = poll_for_state;
+	for (i = 0; i < hvsi_count; i++) {
+		struct hvsi_struct *hp = &hvsi_ports[i];
+
+		free_irq(hp->virq, hp);
+	}
+	tty_driver_kref_put(hvsi_driver);
+
+	return ret;
 }
 device_initcall(hvsi_init);