| Message ID | 20170620211112.1490310-2-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 2da05fa37aec..6a8563633d4b 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -375,10 +375,11 @@ int __tty_insert_flip_char(struct tty_port *port, unsigned char ch, char flag) struct tty_buffer *tb = port->buf.tail; int flags = (flag == TTY_NORMAL) ? TTYB_NORMAL : 0; - if (!tty_buffer_request_room(port, 1)) + if (!__tty_buffer_request_room(port, 1, flags)) return 0; - *flag_buf_ptr(tb, tb->used) = flag; + if (~tb->flags & TTYB_NORMAL) + *flag_buf_ptr(tb, tb->used) = flag; *char_buf_ptr(tb, tb->used++) = ch; return 1;
While working on improving the fast path of tty_insert_flip_char(), I noticed that by calling tty_buffer_request_room(), we needlessly move to the separate flag buffer mode for the tty, even when all characters use TTY_NORMAL as the flag. This changes the code to call __tty_buffer_request_room() with the correct flag, which will then allocate a regular buffer when it rounds out of space but no special flags have been used. I'm guessing that this is the behavior that Peter Hurley intended when he introduced the compacted flip buffers. Fixes: acc0f67f307f ("tty: Halve flip buffer GFP_ATOMIC memory consumption") Cc: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- This patch is just based on my reading of the source code, it's possible that I missed something and the previous behavior was intentional, so please review carefully. --- drivers/tty/tty_buffer.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)