Char: moxa, rework open/close
authorJiri Slaby <jirislaby@gmail.com>
Wed, 30 Apr 2008 07:53:45 +0000 (00:53 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 30 Apr 2008 15:29:43 +0000 (08:29 -0700)
- add locking to open/close/hangup and ioctl (tiocm)
- add pci hot-un-plug support (hangup on board remove, wait for openers)
- cleanup block_till_ready
- move close code common to close/hangup into separate function to be
  able to call it from open when hangup occurs while block_till_ready
- let ldisc flush on tty layer, it will do it after we return

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Tested-by: Oyvind Aabling <Oyvind.Aabling@uni-c.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/char/moxa.c

index abcc16eba44f3a11aae89684a72bbf98e97224cc..af8077c25cbe09d584be17a580b2cd9476d06f04 100644 (file)
@@ -42,7 +42,6 @@
 #include <linux/pci.h>
 #include <linux/init.h>
 #include <linux/bitops.h>
-#include <linux/completion.h>
 
 #include <asm/system.h>
 #include <asm/io.h>
@@ -134,13 +133,11 @@ struct moxa_port {
 
        int type;
        int close_delay;
-       int count;
-       int blocked_open;
+       unsigned int count;
        int asyncflags;
        int cflag;
        unsigned long statusflags;
        wait_queue_head_t open_wait;
-       struct completion close_wait;
 
        u8 DCDState;
        u8 lineCtrl;
@@ -167,6 +164,7 @@ static int ttymajor = MOXAMAJOR;
 static struct mon_str moxaLog;
 static unsigned int moxaFuncTout = HZ / 2;
 static unsigned int moxaLowWaterChk;
+static DEFINE_MUTEX(moxa_openlock);
 /* Variables for insmod */
 #ifdef MODULE
 static unsigned long baseaddr[MAX_BOARDS];
@@ -209,8 +207,6 @@ static int moxa_tiocmset(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear);
 static void moxa_poll(unsigned long);
 static void moxa_set_tty_param(struct tty_struct *, struct ktermios *);
-static int moxa_block_till_ready(struct tty_struct *, struct file *,
-                           struct moxa_port *);
 static void moxa_setup_empty_event(struct tty_struct *);
 static void moxa_shut_down(struct moxa_port *);
 /*
@@ -280,7 +276,7 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
 {
        struct moxa_port *ch = tty->driver_data;
        void __user *argp = (void __user *)arg;
-       int status;
+       int status, ret = 0;
 
        if (tty->index == MAX_PORTS) {
                if (cmd != MOXA_GETDATACOUNT && cmd != MOXA_GET_IOQUEUE &&
@@ -292,17 +288,19 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
        switch (cmd) {
        case MOXA_GETDATACOUNT:
                moxaLog.tick = jiffies;
-               return copy_to_user(argp, &moxaLog, sizeof(moxaLog)) ?
-                       -EFAULT : 0;
+               if (copy_to_user(argp, &moxaLog, sizeof(moxaLog)))
+                       ret = -EFAULT;
+               break;
        case MOXA_FLUSH_QUEUE:
                MoxaPortFlushData(ch, arg);
-               return 0;
+               break;
        case MOXA_GET_IOQUEUE: {
                struct moxaq_str __user *argm = argp;
                struct moxaq_str tmp;
                struct moxa_port *p;
                unsigned int i, j;
 
+               mutex_lock(&moxa_openlock);
                for (i = 0; i < MAX_BOARDS; i++) {
                        p = moxa_boards[i].ports;
                        for (j = 0; j < MAX_PORTS_PER_BOARD; j++, p++, argm++) {
@@ -311,23 +309,29 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
                                        tmp.inq = MoxaPortRxQueue(p);
                                        tmp.outq = MoxaPortTxQueue(p);
                                }
-                               if (copy_to_user(argm, &tmp, sizeof(tmp)))
+                               if (copy_to_user(argm, &tmp, sizeof(tmp))) {
+                                       mutex_unlock(&moxa_openlock);
                                        return -EFAULT;
+                               }
                        }
                }
-               return 0;
+               mutex_unlock(&moxa_openlock);
+               break;
        } case MOXA_GET_OQUEUE:
                status = MoxaPortTxQueue(ch);
-               return put_user(status, (unsigned long __user *)argp);
+               ret = put_user(status, (unsigned long __user *)argp);
+               break;
        case MOXA_GET_IQUEUE:
                status = MoxaPortRxQueue(ch);
-               return put_user(status, (unsigned long __user *)argp);
+               ret = put_user(status, (unsigned long __user *)argp);
+               break;
        case MOXA_GETMSTATUS: {
                struct mxser_mstatus __user *argm = argp;
                struct mxser_mstatus tmp;
                struct moxa_port *p;
                unsigned int i, j;
 
+               mutex_lock(&moxa_openlock);
                for (i = 0; i < MAX_BOARDS; i++) {
                        p = moxa_boards[i].ports;
                        for (j = 0; j < MAX_PORTS_PER_BOARD; j++, p++, argm++) {
@@ -348,18 +352,29 @@ static int moxa_ioctl(struct tty_struct *tty, struct file *file,
                                else
                                        tmp.cflag = p->tty->termios->c_cflag;
 copy:
-                               if (copy_to_user(argm, &tmp, sizeof(tmp)))
+                               if (copy_to_user(argm, &tmp, sizeof(tmp))) {
+                                       mutex_unlock(&moxa_openlock);
                                        return -EFAULT;
+                               }
                        }
                }
-               return 0;
+               mutex_unlock(&moxa_openlock);
+               break;
        }
        case TIOCGSERIAL:
-               return moxa_get_serial_info(ch, argp);
+               mutex_lock(&moxa_openlock);
+               ret = moxa_get_serial_info(ch, argp);
+               mutex_unlock(&moxa_openlock);
+               break;
        case TIOCSSERIAL:
-               return moxa_set_serial_info(ch, argp);
+               mutex_lock(&moxa_openlock);
+               ret = moxa_set_serial_info(ch, argp);
+               mutex_unlock(&moxa_openlock);
+               break;
+       default:
+               ret = -ENOIOCTLCMD;
        }
-       return -ENOIOCTLCMD;
+       return ret;
 }
 
 static void moxa_break_ctl(struct tty_struct *tty, int state)
@@ -817,7 +832,6 @@ static int moxa_init_board(struct moxa_board_conf *brd, struct device *dev)
                p->close_delay = 5 * HZ / 10;
                p->cflag = B9600 | CS8 | CREAD | CLOCAL | HUPCL;
                init_waitqueue_head(&p->open_wait);
-               init_completion(&p->close_wait);
        }
 
        switch (brd->boardType) {
@@ -861,9 +875,29 @@ err:
 
 static void moxa_board_deinit(struct moxa_board_conf *brd)
 {
+       unsigned int a, opened;
+
+       mutex_lock(&moxa_openlock);
        spin_lock_bh(&moxa_lock);
        brd->ready = 0;
        spin_unlock_bh(&moxa_lock);
+
+       /* pci hot-un-plug support */
+       for (a = 0; a < brd->numPorts; a++)
+               if (brd->ports[a].asyncflags & ASYNC_INITIALIZED)
+                       tty_hangup(brd->ports[a].tty);
+       while (1) {
+               opened = 0;
+               for (a = 0; a < brd->numPorts; a++)
+                       if (brd->ports[a].asyncflags & ASYNC_INITIALIZED)
+                               opened++;
+               mutex_unlock(&moxa_openlock);
+               if (!opened)
+                       break;
+               msleep(50);
+               mutex_lock(&moxa_openlock);
+       }
+
        iounmap(brd->basemem);
        brd->basemem = NULL;
        kfree(brd->ports);
@@ -1061,6 +1095,49 @@ static void __exit moxa_exit(void)
 module_init(moxa_init);
 module_exit(moxa_exit);
 
+static void moxa_close_port(struct moxa_port *ch)
+{
+       moxa_shut_down(ch);
+       MoxaPortFlushData(ch, 2);
+       ch->asyncflags &= ~ASYNC_NORMAL_ACTIVE;
+       ch->tty->driver_data = NULL;
+       ch->tty = NULL;
+}
+
+static int moxa_block_till_ready(struct tty_struct *tty, struct file *filp,
+                           struct moxa_port *ch)
+{
+       DEFINE_WAIT(wait);
+       int retval = 0;
+       u8 dcd;
+
+       while (1) {
+               prepare_to_wait(&ch->open_wait, &wait, TASK_INTERRUPTIBLE);
+               if (tty_hung_up_p(filp)) {
+#ifdef SERIAL_DO_RESTART
+                       retval = -ERESTARTSYS;
+#else
+                       retval = -EAGAIN;
+#endif
+                       break;
+               }
+               spin_lock_bh(&moxa_lock);
+               dcd = ch->DCDState;
+               spin_unlock_bh(&moxa_lock);
+               if (dcd)
+                       break;
+
+               if (signal_pending(current)) {
+                       retval = -ERESTARTSYS;
+                       break;
+               }
+               schedule();
+       }
+       finish_wait(&ch->open_wait, &wait);
+
+       return retval;
+}
+
 static int moxa_open(struct tty_struct *tty, struct file *filp)
 {
        struct moxa_board_conf *brd;
@@ -1072,9 +1149,13 @@ static int moxa_open(struct tty_struct *tty, struct file *filp)
        if (port == MAX_PORTS) {
                return capable(CAP_SYS_ADMIN) ? 0 : -EPERM;
        }
+       if (mutex_lock_interruptible(&moxa_openlock))
+               return -ERESTARTSYS;
        brd = &moxa_boards[port / MAX_PORTS_PER_BOARD];
-       if (!brd->ready)
+       if (!brd->ready) {
+               mutex_unlock(&moxa_openlock);
                return -ENODEV;
+       }
 
        ch = &brd->ports[port % MAX_PORTS_PER_BOARD];
        ch->count++;
@@ -1085,19 +1166,24 @@ static int moxa_open(struct tty_struct *tty, struct file *filp)
                moxa_set_tty_param(tty, tty->termios);
                MoxaPortLineCtrl(ch, 1, 1);
                MoxaPortEnable(ch);
+               MoxaSetFifo(ch, ch->type == PORT_16550A);
                ch->asyncflags |= ASYNC_INITIALIZED;
        }
-       retval = moxa_block_till_ready(tty, filp, ch);
+       mutex_unlock(&moxa_openlock);
 
-       moxa_unthrottle(tty);
-
-       if (ch->type == PORT_16550A) {
-               MoxaSetFifo(ch, 1);
-       } else {
-               MoxaSetFifo(ch, 0);
-       }
+       retval = 0;
+       if (!(filp->f_flags & O_NONBLOCK) && !C_CLOCAL(tty))
+               retval = moxa_block_till_ready(tty, filp, ch);
+       mutex_lock(&moxa_openlock);
+       if (retval) {
+               if (ch->count) /* 0 means already hung up... */
+                       if (--ch->count == 0)
+                               moxa_close_port(ch);
+       } else
+               ch->asyncflags |= ASYNC_NORMAL_ACTIVE;
+       mutex_unlock(&moxa_openlock);
 
-       return (retval);
+       return retval;
 }
 
 static void moxa_close(struct tty_struct *tty, struct file *filp)
@@ -1106,18 +1192,14 @@ static void moxa_close(struct tty_struct *tty, struct file *filp)
        int port;
 
        port = tty->index;
-       if (port == MAX_PORTS) {
-               return;
-       }
-       if (tty->driver_data == NULL) {
+       if (port == MAX_PORTS || tty_hung_up_p(filp))
                return;
-       }
-       if (tty_hung_up_p(filp)) {
-               return;
-       }
-       ch = (struct moxa_port *) tty->driver_data;
 
-       if ((tty->count == 1) && (ch->count != 1)) {
+       mutex_lock(&moxa_openlock);
+       ch = tty->driver_data;
+       if (ch == NULL)
+               goto unlock;
+       if (tty->count == 1 && ch->count != 1) {
                printk(KERN_WARNING "moxa_close: bad serial port count; "
                        "tty->count is 1, ch->count is %d\n", ch->count);
                ch->count = 1;
@@ -1127,33 +1209,18 @@ static void moxa_close(struct tty_struct *tty, struct file *filp)
                        "device=%s\n", tty->name);
                ch->count = 0;
        }
-       if (ch->count) {
-               return;
-       }
-       ch->asyncflags |= ASYNC_CLOSING;
+       if (ch->count)
+               goto unlock;
 
        ch->cflag = tty->termios->c_cflag;
        if (ch->asyncflags & ASYNC_INITIALIZED) {
                moxa_setup_empty_event(tty);
                tty_wait_until_sent(tty, 30 * HZ);      /* 30 seconds timeout */
        }
-       moxa_shut_down(ch);
-       MoxaPortFlushData(ch, 2);
 
-       if (tty->driver->flush_buffer)
-               tty->driver->flush_buffer(tty);
-       tty_ldisc_flush(tty);
-                       
-       tty->closing = 0;
-       ch->tty = NULL;
-       if (ch->blocked_open) {
-               if (ch->close_delay) {
-                       msleep_interruptible(jiffies_to_msecs(ch->close_delay));
-               }
-               wake_up_interruptible(&ch->open_wait);
-       }
-       ch->asyncflags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING);
-       complete_all(&ch->close_wait);
+       moxa_close_port(ch);
+unlock:
+       mutex_unlock(&moxa_openlock);
 }
 
 static int moxa_write(struct tty_struct *tty,
@@ -1249,11 +1316,15 @@ static void moxa_put_char(struct tty_struct *tty, unsigned char c)
 
 static int moxa_tiocmget(struct tty_struct *tty, struct file *file)
 {
-       struct moxa_port *ch = tty->driver_data;
+       struct moxa_port *ch;
        int flag = 0, dtr, rts;
 
-       if (!ch)
+       mutex_lock(&moxa_openlock);
+       ch = tty->driver_data;
+       if (!ch) {
+               mutex_unlock(&moxa_openlock);
                return -EINVAL;
+       }
 
        MoxaPortGetLineOut(ch, &dtr, &rts);
        if (dtr)
@@ -1267,19 +1338,24 @@ static int moxa_tiocmget(struct tty_struct *tty, struct file *file)
                flag |= TIOCM_DSR;
        if (dtr & 4)
                flag |= TIOCM_CD;
+       mutex_unlock(&moxa_openlock);
        return flag;
 }
 
 static int moxa_tiocmset(struct tty_struct *tty, struct file *file,
                         unsigned int set, unsigned int clear)
 {
-       struct moxa_port *ch = tty->driver_data;
+       struct moxa_port *ch;
        int port;
        int dtr, rts;
 
        port = tty->index;
-       if (!ch)
+       mutex_lock(&moxa_openlock);
+       ch = tty->driver_data;
+       if (!ch) {
+               mutex_unlock(&moxa_openlock);
                return -EINVAL;
+       }
 
        MoxaPortGetLineOut(ch, &dtr, &rts);
        if (set & TIOCM_RTS)
@@ -1291,6 +1367,7 @@ static int moxa_tiocmset(struct tty_struct *tty, struct file *file,
        if (clear & TIOCM_DTR)
                dtr = 0;
        MoxaPortLineCtrl(ch, dtr, rts);
+       mutex_unlock(&moxa_openlock);
        return 0;
 }
 
@@ -1348,13 +1425,18 @@ static void moxa_start(struct tty_struct *tty)
 
 static void moxa_hangup(struct tty_struct *tty)
 {
-       struct moxa_port *ch = (struct moxa_port *) tty->driver_data;
+       struct moxa_port *ch;
 
-       moxa_flush_buffer(tty);
-       moxa_shut_down(ch);
+       mutex_lock(&moxa_openlock);
+       ch = tty->driver_data;
+       if (ch == NULL) {
+               mutex_unlock(&moxa_openlock);
+               return;
+       }
        ch->count = 0;
-       ch->asyncflags &= ~ASYNC_NORMAL_ACTIVE;
-       ch->tty = NULL;
+       moxa_close_port(ch);
+       mutex_unlock(&moxa_openlock);
+
        wake_up_interruptible(&ch->open_wait);
 }
 
@@ -1363,11 +1445,8 @@ static void moxa_new_dcdstate(struct moxa_port *p, u8 dcd)
        dcd = !!dcd;
 
        if ((dcd != p->DCDState) && p->tty && C_CLOCAL(p->tty)) {
-               if (!dcd) {
+               if (!dcd)
                        tty_hangup(p->tty);
-                       p->asyncflags &= ~ASYNC_NORMAL_ACTIVE;
-               }
-               wake_up_interruptible(&p->open_wait);
        }
        p->DCDState = dcd;
 }
@@ -1499,91 +1578,6 @@ static void moxa_set_tty_param(struct tty_struct *tty, struct ktermios *old_term
        tty_encode_baud_rate(tty, baud, baud);
 }
 
-static int moxa_block_till_ready(struct tty_struct *tty, struct file *filp,
-                           struct moxa_port *ch)
-{
-       DECLARE_WAITQUEUE(wait,current);
-       int retval;
-       int do_clocal = C_CLOCAL(tty);
-
-       /*
-        * If the device is in the middle of being closed, then block
-        * until it's done, and then try again.
-        */
-       if (tty_hung_up_p(filp) || (ch->asyncflags & ASYNC_CLOSING)) {
-               if (ch->asyncflags & ASYNC_CLOSING)
-                       wait_for_completion_interruptible(&ch->close_wait);
-#ifdef SERIAL_DO_RESTART
-               if (ch->asyncflags & ASYNC_HUP_NOTIFY)
-                       return (-EAGAIN);
-               else
-                       return (-ERESTARTSYS);
-#else
-               return (-EAGAIN);
-#endif
-       }
-       /*
-        * If non-blocking mode is set, then make the check up front
-        * and then exit.
-        */
-       if (filp->f_flags & O_NONBLOCK) {
-               ch->asyncflags |= ASYNC_NORMAL_ACTIVE;
-               return (0);
-       }
-       /*
-        * Block waiting for the carrier detect and the line to become free
-        */
-       retval = 0;
-       add_wait_queue(&ch->open_wait, &wait);
-       pr_debug("block_til_ready before block: ttys%d, count = %d\n",
-               tty->index, ch->count);
-       spin_lock_bh(&moxa_lock);
-       if (!tty_hung_up_p(filp))
-               ch->count--;
-       ch->blocked_open++;
-       spin_unlock_bh(&moxa_lock);
-
-       while (1) {
-               set_current_state(TASK_INTERRUPTIBLE);
-               if (tty_hung_up_p(filp) ||
-                   !(ch->asyncflags & ASYNC_INITIALIZED)) {
-#ifdef SERIAL_DO_RESTART
-                       if (ch->asyncflags & ASYNC_HUP_NOTIFY)
-                               retval = -EAGAIN;
-                       else
-                               retval = -ERESTARTSYS;
-#else
-                       retval = -EAGAIN;
-#endif
-                       break;
-               }
-               if (!(ch->asyncflags & ASYNC_CLOSING) && (do_clocal ||
-                               ch->DCDState))
-                       break;
-
-               if (signal_pending(current)) {
-                       retval = -ERESTARTSYS;
-                       break;
-               }
-               schedule();
-       }
-       set_current_state(TASK_RUNNING);
-       remove_wait_queue(&ch->open_wait, &wait);
-
-       spin_lock_bh(&moxa_lock);
-       if (!tty_hung_up_p(filp))
-               ch->count++;
-       ch->blocked_open--;
-       spin_unlock_bh(&moxa_lock);
-       pr_debug("block_til_ready after blocking: ttys%d, count = %d\n",
-               tty->index, ch->count);
-       if (retval)
-               return (retval);
-       /* FIXME: review to see if we need to use set_bit on these */
-       ch->asyncflags |= ASYNC_NORMAL_ACTIVE;
-       return 0;
-}
-
 static void moxa_setup_empty_event(struct tty_struct *tty)
 {
        struct moxa_port *ch = tty->driver_data;
@@ -1595,22 +1589,22 @@ static void moxa_setup_empty_event(struct tty_struct *tty)
 
 static void moxa_shut_down(struct moxa_port *ch)
 {
-       struct tty_struct *tp;
+       struct tty_struct *tp = ch->tty;
 
        if (!(ch->asyncflags & ASYNC_INITIALIZED))
                return;
 
-       tp = ch->tty;
-
        MoxaPortDisable(ch);
 
        /*
         * If we're a modem control device and HUPCL is on, drop RTS & DTR.
         */
-       if (tp->termios->c_cflag & HUPCL)
+       if (C_HUPCL(tp))
                MoxaPortLineCtrl(ch, 0, 0);
 
+       spin_lock_bh(&moxa_lock);
        ch->asyncflags &= ~ASYNC_INITIALIZED;
+       spin_unlock_bh(&moxa_lock);
 }
 
 /*****************************************************************************
@@ -2029,7 +2023,9 @@ static int MoxaPortLineStatus(struct moxa_port *port)
        val &= 0x0B;
        if (val & 8)
                val |= 4;
+       spin_lock_bh(&moxa_lock);
        moxa_new_dcdstate(port, val & 8);
+       spin_unlock_bh(&moxa_lock);
        val &= 7;
        return val;
 }