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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-10-09 09:17:49 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-12-04 10:52:52 -0800 |
| commit | a4bd78ed215873a68869e41fd59543be8ca38e7f (patch) | |
| tree | 9689b1715c8d03a51a718081235ad60385a5fdcd /arch/mn10300/kernel | |
| parent | 40555946447a394889243e4393e312f65d847e1e (diff) | |
| download | linux-a4bd78ed215873a68869e41fd59543be8ca38e7f.tar.bz2 | |
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: Paul 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>
Diffstat (limited to 'arch/mn10300/kernel')
| -rw-r--r-- | arch/mn10300/kernel/mn10300-serial.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/mn10300/kernel/mn10300-serial.c b/arch/mn10300/kernel/mn10300-serial.c index d7ef1232a82a..4994b570dfd9 100644 --- a/arch/mn10300/kernel/mn10300-serial.c +++ b/arch/mn10300/kernel/mn10300-serial.c @@ -550,7 +550,7 @@ try_again: 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(); |