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Subject[PATCH 3.4 171/176] s390/3215: fix tty output containing tabs
Date
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

3.4.107-rc1 review patch. If anyone has any objections, please let me know.

------------------


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>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
drivers/s390/char/con3215.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/char/con3215.c b/drivers/s390/char/con3215.c
index 4f9f1dc..fa47d8d 100644
--- a/drivers/s390/char/con3215.c
+++ b/drivers/s390/char/con3215.c
@@ -997,12 +997,26 @@ 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;
}

/*
@@ -1149,7 +1163,7 @@ 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);
--
1.9.1


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