[PATCH 1/2] serial: 8250: Use 'hlist_for_each_entry' to simplify code

From: Christophe JAILLET
Date: Wed Apr 28 2021 - 03:30:48 EST


Use 'hlist_for_each_entry' instead of hand writing it.
This saves a few lines of code.

The comment about warning generated by some gcc version is also removed.
The way 'hlist_for_each_entry' is written should prevent such a warning to
be emitted.

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
Compile tested only
---
drivers/tty/serial/8250/8250_core.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index cae61d1ebec5..081b773a54c9 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -172,7 +172,6 @@ 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)
{
struct hlist_head *h;
- struct hlist_node *n;
struct irq_info *i;
int ret;

@@ -180,13 +179,11 @@ static int serial_link_irq_chain(struct uart_8250_port *up)

h = &irq_lists[up->port.irq % NR_IRQ_HASH];

- hlist_for_each(n, h) {
- i = hlist_entry(n, struct irq_info, node);
+ hlist_for_each_entry(i, h, node)
if (i->irq == up->port.irq)
break;
- }

- if (n == NULL) {
+ if (i == NULL) {
i = kzalloc(sizeof(struct irq_info), GFP_KERNEL);
if (i == NULL) {
mutex_unlock(&hash_mutex);
@@ -220,25 +217,18 @@ static int serial_link_irq_chain(struct uart_8250_port *up)

static void serial_unlink_irq_chain(struct uart_8250_port *up)
{
- /*
- * yes, some broken gcc emit "warning: 'i' may be used uninitialized"
- * but no, we are not going to take a patch that assigns NULL below.
- */
struct irq_info *i;
- struct hlist_node *n;
struct hlist_head *h;

mutex_lock(&hash_mutex);

h = &irq_lists[up->port.irq % NR_IRQ_HASH];

- hlist_for_each(n, h) {
- i = hlist_entry(n, struct irq_info, node);
+ hlist_for_each_entry(i, h, node)
if (i->irq == up->port.irq)
break;
- }

- BUG_ON(n == NULL);
+ BUG_ON(i == NULL);
BUG_ON(i->head == NULL);

if (list_empty(i->head))
--
2.30.2