tty: rework break handling

Some hardware needs to do break handling itself and may have partial
support only. Make break_ctl return an error code. Add a tty driver flag
so you can indicate driver hardware side break support.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 28 insertions, 43 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d27a08b374d0..d94cd8410c53 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2849,16 +2849,29 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
 
 static int send_break(struct tty_struct *tty, unsigned int duration)
 {
-        if (tty_write_lock(tty, 0) < 0)
-                return -EINTR;
-        tty->ops->break_ctl(tty, -1);
-        if (!signal_pending(current))
-                msleep_interruptible(duration);
-        tty->ops->break_ctl(tty, 0);
-        tty_write_unlock(tty);
-        if (signal_pending(current))
-                return -EINTR;
-        return 0;
+        int retval;
+
+        if (tty->ops->break_ctl == NULL)
+                return 0;
+
+        if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
+                retval = tty->ops->break_ctl(tty, duration);
+        else {
+                /* Do the work ourselves */
+                if (tty_write_lock(tty, 0) < 0)
+                        return -EINTR;
+                retval = tty->ops->break_ctl(tty, -1);
+                if (retval)
+                        goto out;
+                if (!signal_pending(current))
+                        msleep_interruptible(duration);
+                retval = tty->ops->break_ctl(tty, 0);
+out:
+                tty_write_unlock(tty);
+                if (signal_pending(current))
+                        retval = -EINTR;
+        }
+        return retval;
 }
 
 /**
@@ -2949,36 +2962,6 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
             tty->driver->subtype == PTY_TYPE_MASTER)
                 real_tty = tty->link;
 
-        /*
-         * Break handling by driver
-         */
-
-        retval = -EINVAL;
-
-        if (!tty->ops->break_ctl) {
-                switch (cmd) {
-                case TIOCSBRK:
-                case TIOCCBRK:
-                        if (tty->ops->ioctl)
-                                retval = tty->ops->ioctl(tty, file, cmd, arg);
-                        if (retval != -EINVAL && retval != -ENOIOCTLCMD)
-                                printk(KERN_WARNING "tty: driver %s needs updating to use break_ctl\n", tty->driver->name);
-                        return retval;
-
-                /* These two ioctl's always return success; even if */
-                /* the driver doesn't support them. */
-                case TCSBRK:
-                case TCSBRKP:
-                        if (!tty->ops->ioctl)
-                                return 0;
-                        retval = tty->ops->ioctl(tty, file, cmd, arg);
-                        if (retval != -EINVAL && retval != -ENOIOCTLCMD)
-                                printk(KERN_WARNING "tty: driver %s needs updating to use break_ctl\n", tty->driver->name);
-                        if (retval == -ENOIOCTLCMD)
-                                retval = 0;
-                        return retval;
-                }
-        }
 
         /*
          * Factor out some common prep work
@@ -3000,6 +2983,9 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                 break;
         }
 
+        /*
+         *      Now do the stuff.
+         */
         switch (cmd) {
         case TIOCSTI:
                 return tiocsti(tty, p);
@@ -3043,12 +3029,11 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
          */
         case TIOCSBRK:  /* Turn break on, unconditionally */
                 if (tty->ops->break_ctl)
-                        tty->ops->break_ctl(tty, -1);
+                        return tty->ops->break_ctl(tty, -1);
                 return 0;
-
         case TIOCCBRK:  /* Turn break off, unconditionally */
                 if (tty->ops->break_ctl)
-                        tty->ops->break_ctl(tty, 0);
+                        return tty->ops->break_ctl(tty, 0);
                 return 0;
         case TCSBRK:   /* SVID version: non-zero arg --> no break */
                 /* non-zero arg means wait for all output data