From: Linus Torvalds Date: Sat, 5 Sep 2009 19:46:07 +0000 (-0700) Subject: n_tty: do O_ONLCR translation as a single write X-Git-Tag: firefly_0821_release~13052 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=37f81fa1f63ad38e16125526bb2769ae0ea8d332;p=firefly-linux-kernel-4.4.55.git n_tty: do O_ONLCR translation as a single write When translating CR to CRNL in the n_tty line discipline, we did it as two tty_put_char() calls. Which works, but is stupid, and has caused problems before too with bad interactions with the write_room() logic. The generic USB serial driver had that problem, for example. Now the pty layer had similar issues after being moved to the generic tty buffering code (in commit d945cb9cce20ac7143c2de8d88b187f62db99bdc: "pty: Rework the pty layer to use the normal buffering logic"). So stop doing the silly separate two writes, and do it as a single write instead. That's what the n_tty layer already does for the space expansion of tabs (XTABS), and it means that we'll now always have just a single write for the CRNL to match the single 'tty_write_room()' test, which hopefully means that the next time somebody screws up buffering, it won't cause weeks of debugging. Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c index 973be2f44195..4e28b35024ec 100644 --- a/drivers/char/n_tty.c +++ b/drivers/char/n_tty.c @@ -300,8 +300,7 @@ static int do_output_char(unsigned char c, struct tty_struct *tty, int space) if (space < 2) return -1; tty->canon_column = tty->column = 0; - tty_put_char(tty, '\r'); - tty_put_char(tty, c); + tty->ops->write(tty, "\r\n", 2); return 2; } tty->canon_column = tty->column;