linux-kernel - [PATCH v2 3/9] serial: fsl_lpuart: don't restore interrupt state in ISR

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Message-Id: <20210512141255.18277-4-michael@walle.cc>
Date:   Wed, 12 May 2021 16:12:49 +0200
From:   Michael Walle <michael@...le.cc>
To:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Angelo Dureghello <angelo.dureghello@...esys.com>,
        Johan Hovold <johan@...nel.org>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Michael Walle <michael@...le.cc>
Subject: [PATCH v2 3/9] serial: fsl_lpuart: don't restore interrupt state in ISR

>From commit 75f4e830fa9c ("serial: do not restore interrupt state in
sysrq helper"):

  Since commit 81e2073c175b ("genirq: Disable interrupts for force
  threaded handlers") interrupt handlers that are not explicitly
  requested as threaded are always called with interrupts disabled and
  there is no need to save the interrupt state when taking the port
  lock.

Apply this also to fsl_lpuart in prepartion for sysrq handling with
uart_unlock_and_check_sysrq().

Signed-off-by: Michael Walle <michael@...le.cc>
---
 drivers/tty/serial/fsl_lpuart.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index b76ddc0d8edc..37e02d992c0b 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -824,21 +824,18 @@ static unsigned int lpuart32_tx_empty(struct uart_port *port)
 
 static void lpuart_txint(struct lpuart_port *sport)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 	lpuart_transmit_buffer(sport);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 }
 
 static void lpuart_rxint(struct lpuart_port *sport)
 {
 	unsigned int flg, ignored = 0, overrun = 0;
 	struct tty_port *port = &sport->port.state->port;
-	unsigned long flags;
 	unsigned char rx, sr;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 
 	while (!(readb(sport->port.membase + UARTSFIFO) & UARTSFIFO_RXEMPT)) {
 		flg = TTY_NORMAL;
@@ -896,28 +893,25 @@ static void lpuart_rxint(struct lpuart_port *sport)
 		writeb(UARTSFIFO_RXOF, sport->port.membase + UARTSFIFO);
 	}
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 
 	tty_flip_buffer_push(port);
 }
 
 static void lpuart32_txint(struct lpuart_port *sport)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 	lpuart32_transmit_buffer(sport);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 }
 
 static void lpuart32_rxint(struct lpuart_port *sport)
 {
 	unsigned int flg, ignored = 0;
 	struct tty_port *port = &sport->port.state->port;
-	unsigned long flags;
 	unsigned long rx, sr;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	spin_lock(&sport->port.lock);
 
 	while (!(lpuart32_read(&sport->port, UARTFIFO) & UARTFIFO_RXEMPT)) {
 		flg = TTY_NORMAL;
@@ -965,7 +959,7 @@ static void lpuart32_rxint(struct lpuart_port *sport)
 	}
 
 out:
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	spin_unlock(&sport->port.lock);
 
 	tty_flip_buffer_push(port);
 }
-- 
2.20.1