[PATCH] Serial: Adjust serial locking

This patch changes the way serial ports are locked when getting modem
status.  This change is necessary because we will need to atomically
read the modem status and take action depending on the CTS status.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index e9c0178cd202dafa7097e545152afe49a11b6628..ac7eabbf662aaf9d83814debb4f39d0c79043faf 100644 (file)
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -107,8 +107,8 @@ hardware.
        indicate that the signal is permanently active.  If RI is
        not available, the signal should not be indicated as active.
 
-       Locking: none.
-       Interrupts: caller dependent.
+       Locking: port->lock taken.
+       Interrupts: locally disabled.
        This call must not sleep
 
   stop_tx(port,tty_stop)

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 34e75bc8f4cc770cf60973bf87ad3959136f4ec0..b53b53bb1475b7954406d4a4bc5d0c7203a0621e 100644 (file)
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1376,13 +1376,10 @@ static unsigned int serial8250_tx_empty(struct uart_port *port)
 static unsigned int serial8250_get_mctrl(struct uart_port *port)
 {
        struct uart_8250_port *up = (struct uart_8250_port *)port;
-       unsigned long flags;
        unsigned char status;
        unsigned int ret;
 
-       spin_lock_irqsave(&up->port.lock, flags);
        status = serial_in(up, UART_MSR);
-       spin_unlock_irqrestore(&up->port.lock, flags);
 
        ret = 0;
        if (status & UART_MSR_DCD)

diff --git a/drivers/serial/au1x00_uart.c b/drivers/serial/au1x00_uart.c
index 5400dc2c087e59eae61feb19677df7cc32bbbeda..6104aeef12439e156928a16f77267d2215b19d6f 100644 (file)
--- a/drivers/serial/au1x00_uart.c
+++ b/drivers/serial/au1x00_uart.c
@@ -556,13 +556,10 @@ static unsigned int serial8250_tx_empty(struct uart_port *port)
 static unsigned int serial8250_get_mctrl(struct uart_port *port)
 {
        struct uart_8250_port *up = (struct uart_8250_port *)port;
-       unsigned long flags;
        unsigned char status;
        unsigned int ret;
 
-       spin_lock_irqsave(&up->port.lock, flags);
        status = serial_in(up, UART_MSR);
-       spin_unlock_irqrestore(&up->port.lock, flags);
 
        ret = 0;
        if (status & UART_MSR_DCD)

diff --git a/drivers/serial/ip22zilog.c b/drivers/serial/ip22zilog.c
index 3ea46c069f6f1c00ea73858ee83ebd1e5e4e1284..ea5bf4d4daa3016db79933b268ae5240fa63e952 100644 (file)
--- a/drivers/serial/ip22zilog.c
+++ b/drivers/serial/ip22zilog.c
@@ -518,27 +518,28 @@ static irqreturn_t ip22zilog_interrupt(int irq, void *dev_id, struct pt_regs *re
 static __inline__ unsigned char ip22zilog_read_channel_status(struct uart_port *port)
 {
        struct zilog_channel *channel;
-       unsigned long flags;
        unsigned char status;
 
-       spin_lock_irqsave(&port->lock, flags);
-
        channel = ZILOG_CHANNEL_FROM_PORT(port);
        status = readb(&channel->control);
        ZSDELAY();
 
-       spin_unlock_irqrestore(&port->lock, flags);
-
        return status;
 }
 
 /* The port lock is not held.  */
 static unsigned int ip22zilog_tx_empty(struct uart_port *port)
 {
+       unsigned long flags;
        unsigned char status;
        unsigned int ret;
 
+       spin_lock_irqsave(&port->lock, flags);
+
        status = ip22zilog_read_channel_status(port);
+
+       spin_unlock_irqrestore(&port->lock, flags);
+
        if (status & Tx_BUF_EMP)
                ret = TIOCSER_TEMT;
        else
@@ -547,7 +548,7 @@ static unsigned int ip22zilog_tx_empty(struct uart_port *port)
        return ret;
 }
 
-/* The port lock is not held.  */
+/* The port lock is held and interrupts are disabled.  */
 static unsigned int ip22zilog_get_mctrl(struct uart_port *port)
 {
        unsigned char status;

diff --git a/drivers/serial/mpsc.c b/drivers/serial/mpsc.c
index a2a643318002892201db6c0e2b478401e4d93cdc..e43276c6a954d611021745375b5e2344bc85d266 100644 (file)
--- a/drivers/serial/mpsc.c
+++ b/drivers/serial/mpsc.c
@@ -1058,12 +1058,9 @@ mpsc_get_mctrl(struct uart_port *port)
 {
        struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
        u32 mflags, status;
-       ulong iflags;
 
-       spin_lock_irqsave(&pi->port.lock, iflags);
        status = (pi->mirror_regs) ? pi->MPSC_CHR_10_m :
                readl(pi->mpsc_base + MPSC_CHR_10);
-       spin_unlock_irqrestore(&pi->port.lock, iflags);
 
        mflags = 0;
        if (status & 0x1)

diff --git a/drivers/serial/pmac_zilog.c b/drivers/serial/pmac_zilog.c
index 85abd8a045e088cf2c6414aa52cf91fa1c22dba6..1c9f71617123ad4ecf80674f9a737e22feddabf1 100644 (file)
--- a/drivers/serial/pmac_zilog.c
+++ b/drivers/serial/pmac_zilog.c
@@ -604,7 +604,7 @@ static void pmz_set_mctrl(struct uart_port *port, unsigned int mctrl)
 /* 
  * Get Modem Control bits (only the input ones, the core will
  * or that with a cached value of the control ones)
- * The port lock is not held.
+ * The port lock is held and interrupts are disabled.
  */
 static unsigned int pmz_get_mctrl(struct uart_port *port)
 {
@@ -615,7 +615,7 @@ static unsigned int pmz_get_mctrl(struct uart_port *port)
        if (ZS_IS_ASLEEP(uap) || uap->node == NULL)
                return 0;
 
-       status = pmz_peek_status(to_pmz(port));
+       status = read_zsreg(uap, R0);
 
        ret = 0;
        if (status & DCD)

diff --git a/drivers/serial/pxa.c b/drivers/serial/pxa.c
index 08b08d6ae904dd42f45884387d9968bef7a07445..461c81c93207809381c0f2bc9afe5ecfa23d8d9e 100644 (file)
--- a/drivers/serial/pxa.c
+++ b/drivers/serial/pxa.c
@@ -274,14 +274,11 @@ static unsigned int serial_pxa_tx_empty(struct uart_port *port)
 static unsigned int serial_pxa_get_mctrl(struct uart_port *port)
 {
        struct uart_pxa_port *up = (struct uart_pxa_port *)port;
-       unsigned long flags;
        unsigned char status;
        unsigned int ret;
 
 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
-       spin_lock_irqsave(&up->port.lock, flags);
        status = serial_in(up, UART_MSR);
-       spin_unlock_irqrestore(&up->port.lock, flags);
 
        ret = 0;
        if (status & UART_MSR_DCD)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 36b1ae083fb7b1574d4b8951fdf1efcfec2a68df..f5ce58d0514d35a9e83ef21693bc5fe7feec648a 100644 (file)
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -828,7 +828,10 @@ static int uart_tiocmget(struct tty_struct *tty, struct file *file)
        if ((!file || !tty_hung_up_p(file)) &&
            !(tty->flags & (1 << TTY_IO_ERROR))) {
                result = port->mctrl;
+
+               spin_lock_irq(&port->lock);
                result |= port->ops->get_mctrl(port);
+               spin_unlock_irq(&port->lock);
        }
        up(&state->sem);
 
@@ -1369,6 +1372,7 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
        DECLARE_WAITQUEUE(wait, current);
        struct uart_info *info = state->info;
        struct uart_port *port = state->port;
+       unsigned int mctrl;
 
        info->blocked_open++;
        state->count--;
@@ -1416,7 +1420,10 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
                 * and wait for the carrier to indicate that the
                 * modem is ready for us.
                 */
-               if (port->ops->get_mctrl(port) & TIOCM_CAR)
+               spin_lock_irq(&port->lock);
+               mctrl = port->ops->get_mctrl(port);
+               spin_unlock_irq(&port->lock);
+               if (mctrl & TIOCM_CAR)
                        break;
 
                up(&state->sem);
@@ -1618,7 +1625,9 @@ static int uart_line_info(char *buf, struct uart_driver *drv, int i)
 
        if(capable(CAP_SYS_ADMIN))
        {
+               spin_lock_irq(&port->lock);
                status = port->ops->get_mctrl(port);
+               spin_unlock_irq(&port->lock);
 
                ret += sprintf(buf + ret, " tx:%d rx:%d",
                                port->icount.tx, port->icount.rx);

diff --git a/drivers/serial/serial_txx9.c b/drivers/serial/serial_txx9.c
index 3f1051a4a13f8f51cab2efa2783f287e734c8ecb..d085030df70ba5bd321a0fd5716df8ab31af39e1 100644 (file)
--- a/drivers/serial/serial_txx9.c
+++ b/drivers/serial/serial_txx9.c
@@ -442,13 +442,10 @@ static unsigned int serial_txx9_tx_empty(struct uart_port *port)
 static unsigned int serial_txx9_get_mctrl(struct uart_port *port)
 {
        struct uart_txx9_port *up = (struct uart_txx9_port *)port;
-       unsigned long flags;
        unsigned int ret;
 
-       spin_lock_irqsave(&up->port.lock, flags);
        ret =  ((sio_in(up, TXX9_SIFLCR) & TXX9_SIFLCR_RTSSC) ? 0 : TIOCM_RTS)
                | ((sio_in(up, TXX9_SICISR) & TXX9_SICISR_CTSS) ? 0 : TIOCM_CTS);
-       spin_unlock_irqrestore(&up->port.lock, flags);
 
        return ret;
 }

diff --git a/drivers/serial/sunsab.c b/drivers/serial/sunsab.c
index 10e2990a40d42a2453780c5e045642c28866411e..8d198880756a6a3aef034eb55ca6ca7ea5a212e5 100644 (file)
--- a/drivers/serial/sunsab.c
+++ b/drivers/serial/sunsab.c
@@ -426,18 +426,15 @@ static void sunsab_set_mctrl(struct uart_port *port, unsigned int mctrl)
                sunsab_tx_idle(up);
 }
 
-/* port->lock is not held.  */
+/* port->lock is held by caller and interrupts are disabled.  */
 static unsigned int sunsab_get_mctrl(struct uart_port *port)
 {
        struct uart_sunsab_port *up = (struct uart_sunsab_port *) port;
-       unsigned long flags;
        unsigned char val;
        unsigned int result;
 
        result = 0;
 
-       spin_lock_irqsave(&up->port.lock, flags);
-
        val = readb(&up->regs->r.pvr);
        result |= (val & up->pvr_dsr_bit) ? 0 : TIOCM_DSR;
 
@@ -447,8 +444,6 @@ static unsigned int sunsab_get_mctrl(struct uart_port *port)
        val = readb(&up->regs->r.star);
        result |= (val & SAB82532_STAR_CTS) ? TIOCM_CTS : 0;
 
-       spin_unlock_irqrestore(&up->port.lock, flags);
-
        return result;
 }
 

diff --git a/drivers/serial/sunsu.c b/drivers/serial/sunsu.c
index ddc97c905e14cc7a158a22f339379d0129e81551..d57a3553aea359ac7a3123ae62261f2ed9abbb0d 100644 (file)
--- a/drivers/serial/sunsu.c
+++ b/drivers/serial/sunsu.c
@@ -572,13 +572,10 @@ static unsigned int sunsu_tx_empty(struct uart_port *port)
 static unsigned int sunsu_get_mctrl(struct uart_port *port)
 {
        struct uart_sunsu_port *up = (struct uart_sunsu_port *) port;
-       unsigned long flags;
        unsigned char status;
        unsigned int ret;
 
-       spin_lock_irqsave(&up->port.lock, flags);
        status = serial_in(up, UART_MSR);
-       spin_unlock_irqrestore(&up->port.lock, flags);
 
        ret = 0;
        if (status & UART_MSR_DCD)

diff --git a/drivers/serial/sunzilog.c b/drivers/serial/sunzilog.c
index 8e65206d3d760c0542f8ee6bceb60bc235004f22..bff42a7b89d0ec6e02862fcd656a12500ccc144b 100644 (file)
--- a/drivers/serial/sunzilog.c
+++ b/drivers/serial/sunzilog.c
@@ -610,27 +610,28 @@ static irqreturn_t sunzilog_interrupt(int irq, void *dev_id, struct pt_regs *reg
 static __inline__ unsigned char sunzilog_read_channel_status(struct uart_port *port)
 {
        struct zilog_channel __iomem *channel;
-       unsigned long flags;
        unsigned char status;
 
-       spin_lock_irqsave(&port->lock, flags);
-
        channel = ZILOG_CHANNEL_FROM_PORT(port);
        status = sbus_readb(&channel->control);
        ZSDELAY();
 
-       spin_unlock_irqrestore(&port->lock, flags);
-
        return status;
 }
 
 /* The port lock is not held.  */
 static unsigned int sunzilog_tx_empty(struct uart_port *port)
 {
+       unsigned long flags;
        unsigned char status;
        unsigned int ret;
 
+       spin_lock_irqsave(&port->lock, flags);
+
        status = sunzilog_read_channel_status(port);
+
+       spin_unlock_irqrestore(&port->lock, flags);
+
        if (status & Tx_BUF_EMP)
                ret = TIOCSER_TEMT;
        else
@@ -639,7 +640,7 @@ static unsigned int sunzilog_tx_empty(struct uart_port *port)
        return ret;
 }
 
-/* The port lock is not held.  */
+/* The port lock is held and interrupts are disabled.  */
 static unsigned int sunzilog_get_mctrl(struct uart_port *port)
 {
        unsigned char status;