Commit a4bd78ed authored by Paul E. McKenney's avatar Paul E. McKenney

mn10300: READ_ONCE() now implies smp_read_barrier_depends()

Given that READ_ONCE() now implies smp_read_barrier_depends(),
there is no need for the open-coded smp_read_barrier_depends() in
mn10300_serial_receive_interrupt() and mn10300_serial_poll_get_char().
This commit therefore removes them, but replaces them with comments
calling out that carrying dependencies through non-pointers is quite
dangerous.  Compilers simply know too much about integers.
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: <linux-am33-list@redhat.com>
parent 40555946
......@@ -550,7 +550,7 @@ static void mn10300_serial_receive_interrupt(struct mn10300_serial_port *port)
return;
}
smp_read_barrier_depends();
/* READ_ONCE() enforces dependency, but dangerous through integer!!! */
ch = port->rx_buffer[ix++];
st = port->rx_buffer[ix++];
smp_mb();
......@@ -1728,7 +1728,10 @@ static int mn10300_serial_poll_get_char(struct uart_port *_port)
if (CIRC_CNT(port->rx_inp, ix, MNSC_BUFFER_SIZE) == 0)
return NO_POLL_CHAR;
smp_read_barrier_depends();
/*
* READ_ONCE() enforces dependency, but dangerous
* through integer!!!
*/
ch = port->rx_buffer[ix++];
st = port->rx_buffer[ix++];
smp_mb();
......
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