serial: do not restore interrupt state in sysrq helper

The uart_unlock_and_check_sysrq() helper can be used to defer processing
of sysrq until the interrupt handler has released the port lock and is
about to return.

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.

Instead of adding another sysrq helper for when the interrupt state has
not needlessly been saved, drop the state parameter from
uart_unlock_and_check_sysrq() and update its callers to no longer
explicitly disable interrupts in their interrupt handlers.

Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210416140557.25177-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c b/drivers/tty/serial/8250/8250_aspeed_vuart.c
index 3c239d98747f4f33d8034825aa2cfa998c53590f..61550f24a2d377e45e0a2a718c659b43eab9384c 100644 (file)
--- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
+++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
@@ -320,7 +320,6 @@ static int aspeed_vuart_handle_irq(struct uart_port *port)
 {
        struct uart_8250_port *up = up_to_u8250p(port);
        unsigned int iir, lsr;
-       unsigned long flags;
        int space, count;
 
        iir = serial_port_in(port, UART_IIR);
@@ -328,7 +327,7 @@ static int aspeed_vuart_handle_irq(struct uart_port *port)
        if (iir & UART_IIR_NO_INT)
                return 0;
 
-       spin_lock_irqsave(&port->lock, flags);
+       spin_lock(&port->lock);
 
        lsr = serial_port_in(port, UART_LSR);
 
@@ -364,7 +363,7 @@ static int aspeed_vuart_handle_irq(struct uart_port *port)
        if (lsr & UART_LSR_THRE)
                serial8250_tx_chars(up);
 
-       uart_unlock_and_check_sysrq(port, flags);
+       uart_unlock_and_check_sysrq(port);
 
        return 1;
 }

diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c
index cd19400b65ae924f23466201692e0adb39351674..4e75d2e4f87cb8108ad8ded99b14f2df19cc578e 100644 (file)
--- a/drivers/tty/serial/8250/8250_fsl.c
+++ b/drivers/tty/serial/8250/8250_fsl.c
@@ -30,15 +30,14 @@ struct fsl8250_data {
 int fsl8250_handle_irq(struct uart_port *port)
 {
        unsigned char lsr, orig_lsr;
-       unsigned long flags;
        unsigned int iir;
        struct uart_8250_port *up = up_to_u8250p(port);
 
-       spin_lock_irqsave(&up->port.lock, flags);
+       spin_lock(&up->port.lock);
 
        iir = port->serial_in(port, UART_IIR);
        if (iir & UART_IIR_NO_INT) {
-               spin_unlock_irqrestore(&up->port.lock, flags);
+               spin_unlock(&up->port.lock);
                return 0;
        }
 
@@ -46,7 +45,7 @@ int fsl8250_handle_irq(struct uart_port *port)
        if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) {
                up->lsr_saved_flags &= ~UART_LSR_BI;
                port->serial_in(port, UART_RX);
-               spin_unlock_irqrestore(&up->port.lock, flags);
+               spin_unlock(&up->port.lock);
                return 1;
        }
 
@@ -82,7 +81,9 @@ int fsl8250_handle_irq(struct uart_port *port)
                serial8250_tx_chars(up);
 
        up->lsr_saved_flags = orig_lsr;
-       uart_unlock_and_check_sysrq(&up->port, flags);
+
+       uart_unlock_and_check_sysrq(&up->port);
+
        return 1;
 }
 EXPORT_SYMBOL_GPL(fsl8250_handle_irq);

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 23e0decde33eb40e42cceb508cad9c4e93fc0700..8ac11eaeca51bdfb048aff9d79a0aa7651de9479 100644 (file)
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -1143,7 +1143,6 @@ static int omap_8250_dma_handle_irq(struct uart_port *port)
        struct uart_8250_port *up = up_to_u8250p(port);
        struct omap8250_priv *priv = up->port.private_data;
        unsigned char status;
-       unsigned long flags;
        u8 iir;
 
        serial8250_rpm_get(up);
@@ -1154,7 +1153,7 @@ static int omap_8250_dma_handle_irq(struct uart_port *port)
                return IRQ_HANDLED;
        }
 
-       spin_lock_irqsave(&port->lock, flags);
+       spin_lock(&port->lock);
 
        status = serial_port_in(port, UART_LSR);
 
@@ -1179,7 +1178,8 @@ static int omap_8250_dma_handle_irq(struct uart_port *port)
                }
        }
 
-       uart_unlock_and_check_sysrq(port, flags);
+       uart_unlock_and_check_sysrq(port);
+
        serial8250_rpm_put(up);
        return 1;
 }

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 9019f8f626bb255abdb3fa208a976beec8946aa8..d45dab1ab316473d9e9af8138db33a4ec02b2316 100644 (file)
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1879,14 +1879,13 @@ static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
 int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
 {
        unsigned char status;
-       unsigned long flags;
        struct uart_8250_port *up = up_to_u8250p(port);
        bool skip_rx = false;
 
        if (iir & UART_IIR_NO_INT)
                return 0;
 
-       spin_lock_irqsave(&port->lock, flags);
+       spin_lock(&port->lock);
 
        status = serial_port_in(port, UART_LSR);
 
@@ -1912,7 +1911,8 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
                (up->ier & UART_IER_THRI))
                serial8250_tx_chars(up);
 
-       uart_unlock_and_check_sysrq(port, flags);
+       uart_unlock_and_check_sysrq(port);
+
        return 1;
 }
 EXPORT_SYMBOL_GPL(serial8250_handle_irq);

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 0d85b55ea8233a2761551d6535c436628bcf60f7..00bb88a71606ea15339e655ae3379b3db2762980 100644 (file)
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -818,7 +818,6 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev)
        u32 s_irq_status;
        u32 geni_status;
        struct uart_port *uport = dev;
-       unsigned long flags;
        bool drop_rx = false;
        struct tty_port *tport = &uport->state->port;
        struct qcom_geni_serial_port *port = to_dev_port(uport, uport);
@@ -826,7 +825,8 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev)
        if (uport->suspended)
                return IRQ_NONE;
 
-       spin_lock_irqsave(&uport->lock, flags);
+       spin_lock(&uport->lock);
+
        m_irq_status = readl(uport->membase + SE_GENI_M_IRQ_STATUS);
        s_irq_status = readl(uport->membase + SE_GENI_S_IRQ_STATUS);
        geni_status = readl(uport->membase + SE_GENI_STATUS);
@@ -861,7 +861,7 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev)
                qcom_geni_serial_handle_rx(uport, drop_rx);
 
 out_unlock:
-       uart_unlock_and_check_sysrq(uport, flags);
+       uart_unlock_and_check_sysrq(uport);
 
        return IRQ_HANDLED;
 }

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index e1b684e3384178f963dbd04f5a34d5a393d52d18..d7ed00f1594ef660f9070c164fa61b03002f9be8 100644 (file)
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -500,19 +500,19 @@ static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int c
        return 0;
 }
 
-static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
+static inline void uart_unlock_and_check_sysrq(struct uart_port *port)
 {
        int sysrq_ch;
 
        if (!port->has_sysrq) {
-               spin_unlock_irqrestore(&port->lock, irqflags);
+               spin_unlock(&port->lock);
                return;
        }
 
        sysrq_ch = port->sysrq_ch;
        port->sysrq_ch = 0;
 
-       spin_unlock_irqrestore(&port->lock, irqflags);
+       spin_unlock(&port->lock);
 
        if (sysrq_ch)
                handle_sysrq(sysrq_ch);
@@ -526,9 +526,9 @@ static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int c
 {
        return 0;
 }
-static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
+static inline void uart_unlock_and_check_sysrq(struct uart_port *port)
 {
-       spin_unlock_irqrestore(&port->lock, irqflags);
+       spin_unlock(&port->lock);
 }
 #endif /* CONFIG_MAGIC_SYSRQ_SERIAL */