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 <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index c3c606c52722e14ba98b27ff55a98cff3ac5e0c9..39cae611fe59808e1f05594bf54495f5f65fbdfa 100644 (file)
--- 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 1c8fef0e3ff65755936ac5833a1c5c59711293ff..1d5bacca3652495f14d3356ade6795de1112c487 100644 (file)
--- 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 */