riscom8: fix SMP brokenness

After analyzing the elements that save_flags/cli/sti/restore_flags were
protecting, convert their usages to a global spinlock (the easiest and
most obvious next-step).  There were some usages of flags being
intentionally cached, because the code already knew the state of
interrupts.  These have been taken into account.

This allows us to remove CONFIG_BROKEN_ON_SMP.  Completely untested.

[akpm@linux-foundation.org: use DEFINE_SPINLOCK]
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 466629594776fc4af443dec3ca4dc0fa767d0c4e..eb5687beea91482aca8a149661a0f84af7e52d91 100644 (file)
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -276,7 +276,7 @@ config N_HDLC
 
 config RISCOM8
        tristate "SDL RISCom/8 card support"
-       depends on SERIAL_NONSTANDARD && BROKEN_ON_SMP
+       depends on SERIAL_NONSTANDARD
        help
          This is a driver for the SDL Communications RISCom/8 multiport card,
          which gives you many serial ports. You would need something like

diff --git a/drivers/char/riscom8.c b/drivers/char/riscom8.c
index 102ece4c4e0e8050efe26b36745db83e45069e4b..d130b87d8ed793186e63e13dbb7fc139378076b7 100644 (file)
--- a/drivers/char/riscom8.c
+++ b/drivers/char/riscom8.c
@@ -47,6 +47,7 @@
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/tty_flip.h>
+#include <linux/spinlock.h>
 
 #include <asm/uaccess.h>
 
@@ -81,6 +82,8 @@
 
 static struct tty_driver *riscom_driver;
 
+static DEFINE_SPINLOCK(riscom_lock);
+
 static struct riscom_board rc_board[RC_NBOARD] =  {
        {
                .base   = RC_IOBASE1,
@@ -217,13 +220,14 @@ static void __init rc_init_CD180(struct riscom_board const * bp)
 {
        unsigned long flags;
        
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        rc_out(bp, RC_CTOUT, 0);                   /* Clear timeout             */
        rc_wait_CCR(bp);                           /* Wait for CCR ready        */
        rc_out(bp, CD180_CCR, CCR_HARDRESET);      /* Reset CD180 chip          */
-       sti();
+       spin_unlock_irqrestore(&riscom_lock, flags);
        msleep(50);                                /* Delay 0.05 sec            */
-       cli();
+       spin_lock_irqsave(&riscom_lock, flags);
        rc_out(bp, CD180_GIVR, RC_ID);             /* Set ID for this chip      */
        rc_out(bp, CD180_GICR, 0);                 /* Clear all bits            */
        rc_out(bp, CD180_PILR1, RC_ACK_MINT);      /* Prio for modem intr       */
@@ -234,7 +238,7 @@ static void __init rc_init_CD180(struct riscom_board const * bp)
        rc_out(bp, CD180_PPRH, (RC_OSCFREQ/(1000000/RISCOM_TPS)) >> 8);
        rc_out(bp, CD180_PPRL, (RC_OSCFREQ/(1000000/RISCOM_TPS)) & 0xff);
        
-       restore_flags(flags);
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 /* Main probing routine, also sets irq. */
@@ -812,9 +816,9 @@ static int rc_setup_port(struct riscom_board *bp, struct riscom_port *port)
                }
                port->xmit_buf = (unsigned char *) tmp;
        }
-               
-       save_flags(flags); cli();
-               
+
+       spin_lock_irqsave(&riscom_lock, flags);
+
        if (port->tty) 
                clear_bit(TTY_IO_ERROR, &port->tty->flags);
                
@@ -825,7 +829,7 @@ static int rc_setup_port(struct riscom_board *bp, struct riscom_port *port)
        rc_change_speed(bp, port);
        port->flags |= ASYNC_INITIALIZED;
                
-       restore_flags(flags);
+       spin_unlock_irqrestore(&riscom_lock, flags);
        return 0;
 }
 
@@ -901,6 +905,7 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
        int    retval;
        int    do_clocal = 0;
        int    CD;
+       unsigned long flags;
 
        /*
         * If the device is in the middle of being closed, then block
@@ -936,19 +941,26 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
         */
        retval = 0;
        add_wait_queue(&port->open_wait, &wait);
-       cli();
+
+       spin_lock_irqsave(&riscom_lock, flags);
+
        if (!tty_hung_up_p(filp))
                port->count--;
-       sti();
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
+
        port->blocked_open++;
        while (1) {
-               cli();
+               spin_lock_irqsave(&riscom_lock, flags);
+
                rc_out(bp, CD180_CAR, port_No(port));
                CD = rc_in(bp, CD180_MSVR) & MSVR_CD;
                rc_out(bp, CD180_MSVR, MSVR_RTS);
                bp->DTR &= ~(1u << port_No(port));
                rc_out(bp, RC_DTR, bp->DTR);
-               sti();
+
+               spin_unlock_irqrestore(&riscom_lock, flags);
+
                set_current_state(TASK_INTERRUPTIBLE);
                if (tty_hung_up_p(filp) ||
                    !(port->flags & ASYNC_INITIALIZED)) {
@@ -1020,8 +1032,9 @@ static void rc_close(struct tty_struct * tty, struct file * filp)
        
        if (!port || rc_paranoia_check(port, tty->name, "close"))
                return;
-       
-       save_flags(flags); cli();
+
+       spin_lock_irqsave(&riscom_lock, flags);
+
        if (tty_hung_up_p(filp))
                goto out;
        
@@ -1088,7 +1101,9 @@ static void rc_close(struct tty_struct * tty, struct file * filp)
        }
        port->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING);
        wake_up_interruptible(&port->close_wait);
-out:   restore_flags(flags);
+
+out:
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static int rc_write(struct tty_struct * tty, 
@@ -1107,34 +1122,33 @@ static int rc_write(struct tty_struct * tty,
        if (!tty || !port->xmit_buf)
                return 0;
 
-       save_flags(flags);
        while (1) {
-               cli();          
+               spin_lock_irqsave(&riscom_lock, flags);
+
                c = min_t(int, count, min(SERIAL_XMIT_SIZE - port->xmit_cnt - 1,
                                          SERIAL_XMIT_SIZE - port->xmit_head));
-               if (c <= 0) {
-                       restore_flags(flags);
-                       break;
-               }
+               if (c <= 0)
+                       break;  /* lock continues to be held */
 
                memcpy(port->xmit_buf + port->xmit_head, buf, c);
                port->xmit_head = (port->xmit_head + c) & (SERIAL_XMIT_SIZE-1);
                port->xmit_cnt += c;
-               restore_flags(flags);
+
+               spin_unlock_irqrestore(&riscom_lock, flags);
 
                buf += c;
                count -= c;
                total += c;
        }
 
-       cli();
        if (port->xmit_cnt && !tty->stopped && !tty->hw_stopped &&
            !(port->IER & IER_TXRDY)) {
                port->IER |= IER_TXRDY;
                rc_out(bp, CD180_CAR, port_No(port));
                rc_out(bp, CD180_IER, port->IER);
        }
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 
        return total;
 }
@@ -1150,7 +1164,7 @@ static void rc_put_char(struct tty_struct * tty, unsigned char ch)
        if (!tty || !port->xmit_buf)
                return;
 
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
        
        if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1)
                goto out;
@@ -1158,7 +1172,9 @@ static void rc_put_char(struct tty_struct * tty, unsigned char ch)
        port->xmit_buf[port->xmit_head++] = ch;
        port->xmit_head &= SERIAL_XMIT_SIZE - 1;
        port->xmit_cnt++;
-out:   restore_flags(flags);
+
+out:
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static void rc_flush_chars(struct tty_struct * tty)
@@ -1173,11 +1189,13 @@ static void rc_flush_chars(struct tty_struct * tty)
            !port->xmit_buf)
                return;
 
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        port->IER |= IER_TXRDY;
        rc_out(port_Board(port), CD180_CAR, port_No(port));
        rc_out(port_Board(port), CD180_IER, port->IER);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static int rc_write_room(struct tty_struct * tty)
@@ -1212,9 +1230,11 @@ static void rc_flush_buffer(struct tty_struct *tty)
        if (rc_paranoia_check(port, tty->name, "rc_flush_buffer"))
                return;
 
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
        
        tty_wakeup(tty);
 }
@@ -1231,11 +1251,15 @@ static int rc_tiocmget(struct tty_struct *tty, struct file *file)
                return -ENODEV;
 
        bp = port_Board(port);
-       save_flags(flags); cli();
+
+       spin_lock_irqsave(&riscom_lock, flags);
+
        rc_out(bp, CD180_CAR, port_No(port));
        status = rc_in(bp, CD180_MSVR);
        result = rc_in(bp, RC_RI) & (1u << port_No(port)) ? 0 : TIOCM_RNG;
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
+
        result |= ((status & MSVR_RTS) ? TIOCM_RTS : 0)
                | ((status & MSVR_DTR) ? TIOCM_DTR : 0)
                | ((status & MSVR_CD)  ? TIOCM_CAR : 0)
@@ -1256,7 +1280,8 @@ static int rc_tiocmset(struct tty_struct *tty, struct file *file,
 
        bp = port_Board(port);
 
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        if (set & TIOCM_RTS)
                port->MSVR |= MSVR_RTS;
        if (set & TIOCM_DTR)
@@ -1270,7 +1295,9 @@ static int rc_tiocmset(struct tty_struct *tty, struct file *file,
        rc_out(bp, CD180_CAR, port_No(port));
        rc_out(bp, CD180_MSVR, port->MSVR);
        rc_out(bp, RC_DTR, bp->DTR);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
+
        return 0;
 }
 
@@ -1279,7 +1306,8 @@ static inline void rc_send_break(struct riscom_port * port, unsigned long length
        struct riscom_board *bp = port_Board(port);
        unsigned long flags;
        
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        port->break_length = RISCOM_TPS / HZ * length;
        port->COR2 |= COR2_ETC;
        port->IER  |= IER_TXRDY;
@@ -1289,7 +1317,8 @@ static inline void rc_send_break(struct riscom_port * port, unsigned long length
        rc_wait_CCR(bp);
        rc_out(bp, CD180_CCR, CCR_CORCHG2);
        rc_wait_CCR(bp);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static inline int rc_set_serial_info(struct riscom_port * port,
@@ -1298,7 +1327,6 @@ static inline int rc_set_serial_info(struct riscom_port * port,
        struct serial_struct tmp;
        struct riscom_board *bp = port_Board(port);
        int change_speed;
-       unsigned long flags;
        
        if (copy_from_user(&tmp, newinfo, sizeof(tmp)))
                return -EFAULT;
@@ -1332,9 +1360,11 @@ static inline int rc_set_serial_info(struct riscom_port * port,
                port->closing_wait = tmp.closing_wait;
        }
        if (change_speed)  {
-               save_flags(flags); cli();
+               unsigned long flags;
+
+               spin_lock_irqsave(&riscom_lock, flags);
                rc_change_speed(bp, port);
-               restore_flags(flags);
+               spin_unlock_irqrestore(&riscom_lock, flags);
        }
        return 0;
 }
@@ -1414,17 +1444,19 @@ static void rc_throttle(struct tty_struct * tty)
                return;
        
        bp = port_Board(port);
-       
-       save_flags(flags); cli();
+
+       spin_lock_irqsave(&riscom_lock, flags);
+
        port->MSVR &= ~MSVR_RTS;
        rc_out(bp, CD180_CAR, port_No(port));
-       if (I_IXOFF(tty))  {
+       if (I_IXOFF(tty)) {
                rc_wait_CCR(bp);
                rc_out(bp, CD180_CCR, CCR_SSCH2);
                rc_wait_CCR(bp);
        }
        rc_out(bp, CD180_MSVR, port->MSVR);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static void rc_unthrottle(struct tty_struct * tty)
@@ -1438,7 +1470,8 @@ static void rc_unthrottle(struct tty_struct * tty)
        
        bp = port_Board(port);
        
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        port->MSVR |= MSVR_RTS;
        rc_out(bp, CD180_CAR, port_No(port));
        if (I_IXOFF(tty))  {
@@ -1447,7 +1480,8 @@ static void rc_unthrottle(struct tty_struct * tty)
                rc_wait_CCR(bp);
        }
        rc_out(bp, CD180_MSVR, port->MSVR);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static void rc_stop(struct tty_struct * tty)
@@ -1461,11 +1495,13 @@ static void rc_stop(struct tty_struct * tty)
        
        bp = port_Board(port);
        
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        port->IER &= ~IER_TXRDY;
        rc_out(bp, CD180_CAR, port_No(port));
        rc_out(bp, CD180_IER, port->IER);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 static void rc_start(struct tty_struct * tty)
@@ -1479,13 +1515,15 @@ static void rc_start(struct tty_struct * tty)
        
        bp = port_Board(port);
        
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        if (port->xmit_cnt && port->xmit_buf && !(port->IER & IER_TXRDY))  {
                port->IER |= IER_TXRDY;
                rc_out(bp, CD180_CAR, port_No(port));
                rc_out(bp, CD180_IER, port->IER);
        }
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 /*
@@ -1537,9 +1575,9 @@ static void rc_set_termios(struct tty_struct * tty, struct ktermios * old_termio
            tty->termios->c_iflag == old_termios->c_iflag)
                return;
 
-       save_flags(flags); cli();
+       spin_lock_irqsave(&riscom_lock, flags);
        rc_change_speed(port_Board(port), port);
-       restore_flags(flags);
+       spin_unlock_irqrestore(&riscom_lock, flags);
 
        if ((old_termios->c_cflag & CRTSCTS) &&
            !(tty->termios->c_cflag & CRTSCTS)) {
@@ -1627,11 +1665,12 @@ static void rc_release_drivers(void)
 {
        unsigned long flags;
 
-       save_flags(flags);
-       cli();
+       spin_lock_irqsave(&riscom_lock, flags);
+
        tty_unregister_driver(riscom_driver);
        put_tty_driver(riscom_driver);
-       restore_flags(flags);
+
+       spin_unlock_irqrestore(&riscom_lock, flags);
 }
 
 #ifndef MODULE