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/pmac_zilog.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/pmac_zilog.c')
| -rw-r--r-- | drivers/tty/serial/pmac_zilog.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c index 8193635103ee..f7ad5b903055 100644 --- a/drivers/tty/serial/pmac_zilog.c +++ b/drivers/tty/serial/pmac_zilog.c @@ -653,6 +653,8 @@ static void pmz_start_tx(struct uart_port *port) } else { struct circ_buf *xmit = &port->state->xmit; + if (uart_circ_empty(xmit)) + goto out; write_zsdata(uap, xmit->buf[xmit->tail]); zssync(uap); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); @@ -661,6 +663,7 @@ static void pmz_start_tx(struct uart_port *port) if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(&uap->port); } + out: pmz_debug("pmz: start_tx() done.\n"); } |