diff options
| author |   Peter Hurley <peter@hurleysoftware.com> | 2014-07-06 11:29:52 -0400 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-10 16:31:34 -0700 |
| commit | c557d392fbf5badd693ea1946a4317c87a26a716 (patch) | |
| tree | 10b1369df578934fa8d43fbef7c69fb523ac5ab9 /drivers/tty/serial/m32r_sio.c | |
| parent | Linux 3.16-rc4 (diff) | |
| download | linux-dev-c557d392fbf5badd693ea1946a4317c87a26a716.tar.xz linux-dev-c557d392fbf5badd693ea1946a4317c87a26a716.zip | |
serial: Test for no tx data on tx restart
Commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c,
'serial_core: Fix conditional start_tx on ring buffer not empty'
exposes an incorrect assumption in several drivers' start_tx methods;
the tx ring buffer can, in fact, be empty when restarting tx while
performing flow control.
Affected drivers:
sunsab.c
ip22zilog.c
pmac_zilog.c
sunzilog.c
m32r_sio.c
imx.c
Other in-tree serial drivers either are not affected or already
test for empty tx ring buffer before transmitting.
Test for empty tx ring buffer in start_tx() method, after transmitting
x_char (if applicable).
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Seth Bollinger <sethb@digi.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Cc: stable <stable@vger.kernel.org> # 3.15
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/m32r_sio.c')
| -rw-r--r-- | drivers/tty/serial/m32r_sio.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/tty/serial/m32r_sio.c b/drivers/tty/serial/m32r_sio.c index 68f2c53e0b54..5702828fb62e 100644 --- a/drivers/tty/serial/m32r_sio.c +++ b/drivers/tty/serial/m32r_sio.c @@ -266,9 +266,11 @@ static void m32r_sio_start_tx(struct uart_port *port) if (!(up->ier & UART_IER_THRI)) { up->ier |= UART_IER_THRI; serial_out(up, UART_IER, up->ier); - serial_out(up, UART_TX, xmit->buf[xmit->tail]); - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); - up->port.icount.tx++; + if (!uart_circ_empty(xmit)) { + serial_out(up, UART_TX, xmit->buf[xmit->tail]); + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); + up->port.icount.tx++; + } } while((serial_in(up, UART_LSR) & UART_EMPTY) != UART_EMPTY); #else |