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tty: Use non-atomic state to signal flip buffer flush pending

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Atomic bit ops are no longer required to indicate a flip buffer
flush is pending, as the flush_mutex is sufficient barrier.

Remove the unnecessary port .iflags field and localize flip buffer
state to struct tty_bufhead.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2013-06-15 09:36:13 -04:00 committed by Greg Kroah-Hartman
parent 8c1fb49ba1
commit 0f56bd2f6a
2 changed files with 5 additions and 5 deletions
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7
drivers/tty/tty_buffer.c
View file

@ -189,11 +189,11 @@ void tty_buffer_flush(struct tty_struct *tty)
struct tty_port *port = tty->port;
struct tty_bufhead *buf = &port->buf;
set_bit(TTYP_FLUSHPENDING, &port->iflags);
buf->flushpending = 1;
mutex_lock(&buf->flush_mutex);
__tty_buffer_flush(port);
clear_bit(TTYP_FLUSHPENDING, &port->iflags);
buf->flushpending = 0;
mutex_unlock(&buf->flush_mutex);
}
@ -426,7 +426,7 @@ static void flush_to_ldisc(struct work_struct *work)
int count;
/* Ldisc or user is trying to flush the buffers. */
if (test_bit(TTYP_FLUSHPENDING, &port->iflags))
if (buf->flushpending)
break;
count = head->commit - head->read;
@ -505,6 +505,7 @@ void tty_buffer_init(struct tty_port *port)
buf->tail = &buf->sentinel;
init_llist_head(&buf->free);
atomic_set(&buf->memory_used, 0);
buf->flushpending = 0;
INIT_WORK(&buf->work, flush_to_ldisc);
}

3
include/linux/tty.h
View file

@ -68,6 +68,7 @@ struct tty_bufhead {
struct tty_buffer *head; /* Queue head */
struct work_struct work;
struct mutex flush_mutex;
unsigned int flushpending:1;
struct tty_buffer sentinel;
struct llist_head free; /* Free queue head */
atomic_t memory_used; /* In-use buffers excluding free list */
@ -212,8 +213,6 @@ struct tty_port {
wait_queue_head_t close_wait; /* Close waiters */
wait_queue_head_t delta_msr_wait; /* Modem status change */
unsigned long flags; /* TTY flags ASY_*/
unsigned long iflags; /* TTYP_ internal flags */
#define TTYP_FLUSHPENDING 2 /* Queued buffer flush pending */
unsigned char console:1, /* port is a console */
low_latency:1; /* direct buffer flush */
struct mutex mutex; /* Locking */