s390/3215: fix tty output containing tabs

commit e512d56c799517f33b301d81e9a5e0ebf30c2d1e upstream.

git commit 37f81fa1f63ad38e16125526bb2769ae0ea8d332
"n_tty: do O_ONLCR translation as a single write"
surfaced a bug in the 3215 device driver. In combination this
broke tab expansion for tty ouput.

The cause is an asymmetry in the behaviour of tty3215_ops->write
vs tty3215_ops->put_char. The put_char function scans for '\t'
but the write function does not.

As the driver has logic for the '\t' expansion remove XTABS
from c_oflag of the initial termios as well.

Reported-by: Stephen Powell <zlinuxman@wowway.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 934458a..2c8d79c 100644 (file)
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -993,12 +993,26 @@ static int tty3215_write(struct tty_struct * tty,
                         const unsigned char *buf, int count)
 {
        struct raw3215_info *raw;
+       int i, written;
 
        if (!tty)
                return 0;
        raw = (struct raw3215_info *) tty->driver_data;
-       raw3215_write(raw, buf, count);
-       return count;
+       written = count;
+       while (count > 0) {
+               for (i = 0; i < count; i++)
+                       if (buf[i] == '\t' || buf[i] == '\n')
+                               break;
+               raw3215_write(raw, buf, i);
+               count -= i;
+               buf += i;
+               if (count > 0) {
+                       raw3215_putchar(raw, *buf);
+                       count--;
+                       buf++;
+               }
+       }
+       return written;
 }
 
 /*
@@ -1146,7 +1160,7 @@ static int __init tty3215_init(void)
        driver->subtype = SYSTEM_TYPE_TTY;
        driver->init_termios = tty_std_termios;
        driver->init_termios.c_iflag = IGNBRK | IGNPAR;
-       driver->init_termios.c_oflag = ONLCR | XTABS;
+       driver->init_termios.c_oflag = ONLCR;
        driver->init_termios.c_lflag = ISIG;
        driver->flags = TTY_DRIVER_REAL_RAW;
        tty_set_operations(driver, &tty3215_ops);