From d7a68be4f265be10e24be931c257af30ca55566b Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sat, 15 Jun 2013 09:36:11 -0400 Subject: [PATCH] tty: Only perform flip buffer flush from tty_buffer_flush() Now that dropping the buffer lock is not necessary (as result of converting the spin lock to a mutex), the flip buffer flush no longer needs to be handled by the buffer work. Simply signal a flush is required; the buffer work will exit the i/o loop, which allows tty_buffer_flush() to proceed. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_buffer.c | 63 ++++++++++++++-------------------------- include/linux/tty.h | 1 - 2 files changed, 21 insertions(+), 43 deletions(-) diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index c3c606c52722..39cae611fe59 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -189,19 +189,11 @@ void tty_buffer_flush(struct tty_struct *tty) struct tty_port *port = tty->port; struct tty_bufhead *buf = &port->buf; - mutex_lock(&buf->flush_mutex); - /* If the data is being pushed to the tty layer then we can't - process it here. Instead set a flag and the flush_to_ldisc - path will process the flush request before it exits */ - if (test_bit(TTYP_FLUSHING, &port->iflags)) { - set_bit(TTYP_FLUSHPENDING, &port->iflags); - mutex_unlock(&buf->flush_mutex); - wait_event(tty->read_wait, - test_bit(TTYP_FLUSHPENDING, &port->iflags) == 0); - return; - } + set_bit(TTYP_FLUSHPENDING, &port->iflags); + mutex_lock(&buf->flush_mutex); __tty_buffer_flush(port); + clear_bit(TTYP_FLUSHPENDING, &port->iflags); mutex_unlock(&buf->flush_mutex); } @@ -429,39 +421,26 @@ static void flush_to_ldisc(struct work_struct *work) mutex_lock(&buf->flush_mutex); - if (!test_and_set_bit(TTYP_FLUSHING, &port->iflags)) { - while (1) { - struct tty_buffer *head = buf->head; - int count; - - count = head->commit - head->read; - if (!count) { - if (head->next == NULL) - break; - buf->head = head->next; - tty_buffer_free(port, head); - continue; - } - - mutex_unlock(&buf->flush_mutex); - - count = receive_buf(tty, head, count); - - mutex_lock(&buf->flush_mutex); - - /* Ldisc or user is trying to flush the buffers. - We may have a deferred request to flush the - input buffer, if so pull the chain under the lock - and empty the queue */ - if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) { - __tty_buffer_flush(port); - clear_bit(TTYP_FLUSHPENDING, &port->iflags); - wake_up(&tty->read_wait); - break; - } else if (!count) + while (1) { + struct tty_buffer *head = buf->head; + int count; + + /* Ldisc or user is trying to flush the buffers. */ + if (test_bit(TTYP_FLUSHPENDING, &port->iflags)) + break; + + count = head->commit - head->read; + if (!count) { + if (head->next == NULL) break; + buf->head = head->next; + tty_buffer_free(port, head); + continue; } - clear_bit(TTYP_FLUSHING, &port->iflags); + + count = receive_buf(tty, head, count); + if (!count) + break; } mutex_unlock(&buf->flush_mutex); diff --git a/include/linux/tty.h b/include/linux/tty.h index 1c8fef0e3ff6..1d5bacca3652 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -213,7 +213,6 @@ struct tty_port { wait_queue_head_t delta_msr_wait; /* Modem status change */ unsigned long flags; /* TTY flags ASY_*/ unsigned long iflags; /* TTYP_ internal flags */ -#define TTYP_FLUSHING 1 /* Flushing to ldisc in progress */ #define TTYP_FLUSHPENDING 2 /* Queued buffer flush pending */ unsigned char console:1, /* port is a console */ low_latency:1; /* direct buffer flush */ -- 2.20.1