diff options
| author | David Howells <dhowells@redhat.com> | 2012-12-12 15:36:37 +0000 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2012-12-12 15:46:14 +0000 |
| commit | c98c406eb2c518c7c5bc922fafa1f9fdcb7b76f4 (patch) | |
| tree | a7b5199a61df167bdcc34eb36af97d73bb6b3d0d /arch/mn10300/kernel | |
| parent | 541880d9a2c7871f6370071d55aa6662d329c51e (diff) | |
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/kernel')
| -rw-r--r-- | arch/mn10300/kernel/mn10300-serial.c | 14 |
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)); |