tty: Define ASYNC_ replacement bits
Prepare for relocating kernel private state bits out of tty_port::flags
field; tty_port::flags field is not atomic and can become corrupted
by concurrent updates. It also suffers from the complication of sharing
in a userspace-visible field which must be masked.
Define new tty_port::iflags field and new, substitute bit definitions
for the former ASYNC_* flags.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 89f9c91..4e0dbda0 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -228,7 +228,8 @@
int count; /* Usage count */
wait_queue_head_t open_wait; /* Open waiters */
wait_queue_head_t delta_msr_wait; /* Modem status change */
- unsigned long flags; /* TTY flags ASY_*/
+ unsigned long flags; /* User TTY flags ASYNC_ */
+ unsigned long iflags; /* Internal flags TTY_PORT_ */
unsigned char console:1, /* port is a console */
low_latency:1; /* optional: tune for latency */
struct mutex mutex; /* Locking */
@@ -242,6 +243,19 @@
struct kref kref; /* Ref counter */
};
+/* tty_port::iflags bits -- use atomic bit ops */
+#define TTY_PORT_INITIALIZED 0 /* device is initialized */
+#define TTY_PORT_SUSPENDED 1 /* device is suspended */
+#define TTY_PORT_ACTIVE 2 /* device is open */
+
+/*
+ * uart drivers: use the uart_port::status field and the UPSTAT_* defines
+ * for s/w-based flow control steering and carrier detection status
+ */
+#define TTY_PORT_CTS_FLOW 3 /* h/w flow control enabled */
+#define TTY_PORT_CHECK_CD 4 /* carrier detect enabled */
+
+
/*
* Where all of the state associated with a tty is kept while the tty
* is open. Since the termios state should be kept even if the tty