aboutsummaryrefslogtreecommitdiff
path: root/arch/mn10300
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2012-12-12 15:36:37 +0000
committerDavid Howells <dhowells@redhat.com>2012-12-12 15:46:14 +0000
commitc98c406eb2c518c7c5bc922fafa1f9fdcb7b76f4 (patch)
treea7b5199a61df167bdcc34eb36af97d73bb6b3d0d /arch/mn10300
parent541880d9a2c7871f6370071d55aa6662d329c51e (diff)
downloadlinux-linaro-stable-c98c406eb2c518c7c5bc922fafa1f9fdcb7b76f4.tar.gz
MN10300: ttySM: Use memory barriers correctly in circular buffer logic
Use memory barriers correctly in the circular buffer logic used in the driver, as documented in Documentation/circular-buffers.txt. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Mark Salter <msalter@redhat.com>
Diffstat (limited to 'arch/mn10300')
-rw-r--r--arch/mn10300/kernel/mn10300-serial.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/mn10300/kernel/mn10300-serial.c b/arch/mn10300/kernel/mn10300-serial.c
index 339cef4c8256..131b81f9d6c8 100644
--- a/arch/mn10300/kernel/mn10300-serial.c
+++ b/arch/mn10300/kernel/mn10300-serial.c
@@ -487,16 +487,17 @@ static void mn10300_serial_receive_interrupt(struct mn10300_serial_port *port)
try_again:
/* pull chars out of the hat */
- ix = port->rx_outp;
- if (ix == port->rx_inp) {
+ ix = ACCESS_ONCE(port->rx_outp);
+ if (CIRC_CNT(port->rx_inp, ix, MNSC_BUFFER_SIZE) == 0) {
if (push && !tty->low_latency)
tty_flip_buffer_push(tty);
return;
}
+ smp_read_barrier_depends();
ch = port->rx_buffer[ix++];
st = port->rx_buffer[ix++];
- smp_rmb();
+ smp_mb();
port->rx_outp = ix & (MNSC_BUFFER_SIZE - 1);
port->uart.icount.rx++;
@@ -1657,13 +1658,14 @@ static int mn10300_serial_poll_get_char(struct uart_port *_port)
do {
/* pull chars out of the hat */
- ix = port->rx_outp;
- if (ix == port->rx_inp)
+ ix = ACCESS_ONCE(port->rx_outp);
+ if (CIRC_CNT(port->rx_inp, ix, MNSC_BUFFER_SIZE) == 0)
return NO_POLL_CHAR;
+ smp_read_barrier_depends();
ch = port->rx_buffer[ix++];
st = port->rx_buffer[ix++];
- smp_rmb();
+ smp_mb();
port->rx_outp = ix & (MNSC_BUFFER_SIZE - 1);
} while (st & (SC01STR_FEF | SC01STR_PEF | SC01STR_OEF));