On Wed, Apr 28, 2021 at 09:30:40AM +0200, Christophe JAILLET wrote:
> 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.
I checked the implementation of the macros vs. this usage and below seems legit.
However it indeed needs more test coverage because it's sensitive piece of code.
FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
(with the above caveat)
> 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
>
--
With Best Regards,
Andy Shevchenko
