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authorPeter Hurley <peter@hurleysoftware.com>2014-07-06 11:29:52 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-10 16:31:34 -0700
commitc557d392fbf5badd693ea1946a4317c87a26a716 (patch)
tree10b1369df578934fa8d43fbef7c69fb523ac5ab9
parentcd3de83f147601356395b57a8673e9c5ff1e59d1 (diff)
downloadlinux-c557d392fbf5badd693ea1946a4317c87a26a716.tar.gz
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>
-rw-r--r--drivers/tty/serial/imx.c3
-rw-r--r--drivers/tty/serial/ip22zilog.c2
-rw-r--r--drivers/tty/serial/m32r_sio.c8
-rw-r--r--drivers/tty/serial/pmac_zilog.c3
-rw-r--r--drivers/tty/serial/sunsab.c3
-rw-r--r--drivers/tty/serial/sunzilog.c2
6 files changed, 18 insertions, 3 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index e2f93874989..56bd9aa5615 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -567,6 +567,9 @@ static void imx_start_tx(struct uart_port *port)
struct imx_port *sport = (struct imx_port *)port;
unsigned long temp;
+ if (uart_circ_empty(&port.state->xmit))
+ return;
+
if (USE_IRDA(sport)) {
/* half duplex in IrDA mode; have to disable receive mode */
temp = readl(sport->port.membase + UCR4);
diff --git a/drivers/tty/serial/ip22zilog.c b/drivers/tty/serial/ip22zilog.c
index 1efd4c36ba0..99b7b869786 100644
--- a/drivers/tty/serial/ip22zilog.c
+++ b/drivers/tty/serial/ip22zilog.c
@@ -603,6 +603,8 @@ static void ip22zilog_start_tx(struct uart_port *port)
} else {
struct circ_buf *xmit = &port->state->xmit;
+ if (uart_circ_empty(xmit))
+ return;
writeb(xmit->buf[xmit->tail], &channel->data);
ZSDELAY();
ZS_WSYNC(channel);
diff --git a/drivers/tty/serial/m32r_sio.c b/drivers/tty/serial/m32r_sio.c
index 68f2c53e0b5..5702828fb62 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
diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c
index 8193635103e..f7ad5b90305 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");
}
diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c
index 80a58eca785..2f57df9a71d 100644
--- a/drivers/tty/serial/sunsab.c
+++ b/drivers/tty/serial/sunsab.c
@@ -427,6 +427,9 @@ static void sunsab_start_tx(struct uart_port *port)
struct circ_buf *xmit = &up->port.state->xmit;
int i;
+ if (uart_circ_empty(xmit))
+ return;
+
up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);
writeb(up->interrupt_mask1, &up->regs->w.imr1);
diff --git a/drivers/tty/serial/sunzilog.c b/drivers/tty/serial/sunzilog.c
index a85db8b8715..02df3940b95 100644
--- a/drivers/tty/serial/sunzilog.c
+++ b/drivers/tty/serial/sunzilog.c
@@ -703,6 +703,8 @@ static void sunzilog_start_tx(struct uart_port *port)
} else {
struct circ_buf *xmit = &port->state->xmit;
+ if (uart_circ_empty(xmit))
+ return;
writeb(xmit->buf[xmit->tail], &channel->data);
ZSDELAY();
ZS_WSYNC(channel);