serial: 8250: extract serial_get_or_create_irq_info()

This find-or-create-irq part of the serial_link_irq_chain()'s code is
logically bounded and self-standing. For easier-to-follow code flow,
extract the code to a separate function:
serial_get_or_create_irq_info().

This allows for an easier found-an-irq handling -- simple jump to the
'unlock' label and return. That results in one less 'if' levels.

Note when using guard()s in the upcoming patchset, the label can dropped
altogether.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250611100319.186924-28-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 7a6050f1c094b3947415ee83fb053614b990fa75..d42ceb6ffdc2676f1cb85d99e17f31f9ebbadf6f 100644 (file)
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -129,11 +129,15 @@ static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
        }
 }
 
-static int serial_link_irq_chain(struct uart_8250_port *up)
+/*
+ * Either:
+ * - find the corresponding info in the hashtable and return it, or
+ * - allocate a new one, add it to the hashtable and return it.
+ */
+static struct irq_info *serial_get_or_create_irq_info(const struct uart_8250_port *up)
 {
        struct hlist_head *h;
        struct irq_info *i;
-       int ret;
 
        mutex_lock(&hash_mutex);
 
@@ -141,20 +145,31 @@ static int serial_link_irq_chain(struct uart_8250_port *up)
 
        hlist_for_each_entry(i, h, node)
                if (i->irq == up->port.irq)
-                       break;
+                       goto unlock;
 
+       i = kzalloc(sizeof(*i), GFP_KERNEL);
        if (i == NULL) {
-               i = kzalloc(sizeof(struct irq_info), GFP_KERNEL);
-               if (i == NULL) {
-                       mutex_unlock(&hash_mutex);
-                       return -ENOMEM;
-               }
-               spin_lock_init(&i->lock);
-               i->irq = up->port.irq;
-               hlist_add_head(&i->node, h);
+               i = ERR_PTR(-ENOMEM);
+               goto unlock;
        }
+       spin_lock_init(&i->lock);
+       i->irq = up->port.irq;
+       hlist_add_head(&i->node, h);
+unlock:
        mutex_unlock(&hash_mutex);
 
+       return i;
+}
+
+static int serial_link_irq_chain(struct uart_8250_port *up)
+{
+       struct irq_info *i;
+       int ret;
+
+       i = serial_get_or_create_irq_info(up);
+       if (IS_ERR(i))
+               return PTR_ERR(i);
+
        spin_lock_irq(&i->lock);
 
        if (i->head) {