提交 c98c406e 编写于 作者: D David Howells

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: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NMark Salter <msalter@redhat.com>
上级 541880d9
......@@ -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));
......
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