linux-kernel - [PATCH v2 22/35] tty: nozomi: optimize interrupt

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Message-Id: <20231203193307.542794-21-yury.norov@gmail.com>
Date:   Sun,  3 Dec 2023 11:32:54 -0800
From:   Yury Norov <yury.norov@...il.com>
To:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, linux-serial@...r.kernel.org
Cc:     Yury Norov <yury.norov@...il.com>, Jan Kara <jack@...e.cz>,
        Mirsad Todorovac <mirsad.todorovac@....unizg.hr>,
        Matthew Wilcox <willy@...radead.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
        Alexey Klimov <klimov.linux@...il.com>,
        Bart Van Assche <bvanassche@....org>,
        Sergey Shtylyov <s.shtylyov@....ru>
Subject: [PATCH v2 22/35] tty: nozomi: optimize interrupt_handler()

In exit path of interrupt_handler(), dc->flip map is traversed bit by
bit to find and clear set bits and call tty_flip_buffer_push() for
corresponding ports.

We can do it better by using for_each_test_and_clear_bit(), because it
skips already clear bits.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 drivers/tty/nozomi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
index 02cd40147b3a..de0503247391 100644
--- a/drivers/tty/nozomi.c
+++ b/drivers/tty/nozomi.c
@@ -1220,9 +1220,8 @@ static irqreturn_t interrupt_handler(int irq, void *dev_id)
 exit_handler:
 	spin_unlock(&dc->spin_mutex);
 
-	for (a = 0; a < NOZOMI_MAX_PORTS; a++)
-		if (test_and_clear_bit(a, &dc->flip))
-			tty_flip_buffer_push(&dc->port[a].port);
+	for_each_test_and_clear_bit(a, &dc->flip, NOZOMI_MAX_PORTS)
+		tty_flip_buffer_push(&dc->port[a].port);
 
 	return IRQ_HANDLED;
 none:
-- 
2.40.1