[PATCH 32/33] serial: 8250: use hashtable

Jiri Slaby (SUSE)
2025-06-11T10:04:19Z

Instead of open-coding the hash table, use the one provided by
hashtable.h. The semantics is the same, except the code needs not to
compute the hash bucket on its own.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
---
drivers/tty/serial/8250/8250_core.c | 24 ++++++++----------------
1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 10f25bae9f46..a6ecb8575da4 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -13,6 +13,7 @@
*/

#include <linux/acpi.h>
+#include <linux/hashtable.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ioport.h>
@@ -47,8 +48,8 @@ struct irq_info {
struct list_head *head;
};

-#define NR_IRQ_HASH 32 /* Can be adjusted later */
-static struct hlist_head irq_lists[NR_IRQ_HASH];
+#define IRQ_HASH_BITS 5 /* Can be adjusted later */
+static DEFINE_HASHTABLE(irq_lists, IRQ_HASH_BITS);
static DEFINE_MUTEX(hash_mutex); /* Used to walk the hash */

/*
@@ -75,11 +76,8 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id)

l = i->head;
do {
- struct uart_8250_port *up;
- struct uart_port *port;
-
- up = list_entry(l, struct uart_8250_port, list);
- port = &up->port;
+ struct uart_8250_port *up = list_entry(l, struct uart_8250_port, list);
+ struct uart_port *port = &up->port;

if (port->handle_irq(port)) {
handled = 1;
@@ -132,14 +130,11 @@ static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up)
*/
static struct irq_info *serial_get_or_create_irq_info(const struct uart_8250_port *up)
{
- struct hlist_head *h;
struct irq_info *i;

mutex_lock(&hash_mutex);

- h = &irq_lists[up->port.irq % NR_IRQ_HASH];
-
- hlist_for_each_entry(i, h, node)
+ hash_for_each_possible(irq_lists, i, node, up->port.irq)
if (i->irq == up->port.irq)
goto unlock;

@@ -150,7 +145,7 @@ static struct irq_info *serial_get_or_create_irq_info(const struct uart_8250_por
}
spin_lock_init(&i->lock);
i->irq = up->port.irq;
- hlist_add_head(&i->node, h);
+ hash_add(irq_lists, &i->node, i->irq);
unlock:
mutex_unlock(&hash_mutex);

@@ -189,13 +184,10 @@ static int serial_link_irq_chain(struct uart_8250_port *up)
static void serial_unlink_irq_chain(struct uart_8250_port *up)
{
struct irq_info *i;
- struct hlist_head *h;

mutex_lock(&hash_mutex);

- h = &irq_lists[up->port.irq % NR_IRQ_HASH];
-
- hlist_for_each_entry(i, h, node)
+ hash_for_each_possible(irq_lists, i, node, up->port.irq)
if (i->irq == up->port.irq)
break;

--
2.49.0