3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Johan Hovold johan@kernel.org
commit 1cee38f0363a88db374e50b232ca17b9a4c12fa0 upstream.
When the termios CIBAUD bits are left unset (i.e. B0), we use the same output and input speed and should leave CIBAUD unchanged.
When the user requests a rate using BOTHER and c_ospeed which the driver cannot set exactly, the driver can report back the actual baud rate using tty_termios_encode_baud_rate(). If this rate is close enough to a standard rate however, we could end up setting CIBAUD to a Bfoo value despite the user having left it unset.
This in turn could lead to an unexpected input rate being set on subsequent termios updates.
Fix this by using a zero tolerance value also for the input rate when CIBAUD is clear so that the matching logic works as expected.
Fixes: 78137e3b34e1 ("[PATCH] tty: improve encode_baud_rate logic") Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/tty/tty_ioctl.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/tty/tty_ioctl.c +++ b/drivers/tty/tty_ioctl.c @@ -407,16 +407,20 @@ void tty_termios_encode_baud_rate(struct termios->c_ospeed = obaud;
#ifdef BOTHER + if ((termios->c_cflag >> IBSHIFT) & CBAUD) + ibinput = 1; /* An input speed was specified */ + /* If the user asked for a precise weird speed give a precise weird answer. If they asked for a Bfoo speed they may have problems digesting non-exact replies so fuzz a bit */
- if ((termios->c_cflag & CBAUD) == BOTHER) + if ((termios->c_cflag & CBAUD) == BOTHER) { oclose = 0; + if (!ibinput) + iclose = 0; + } if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) iclose = 0; - if ((termios->c_cflag >> IBSHIFT) & CBAUD) - ibinput = 1; /* An input speed was specified */ #endif termios->c_cflag &= ~CBAUD; #ifdef IBSHIFT