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 89f9c91b40f54bedbfdd862580bcbd0c3fa43827..4e0dbda051807d9ceef174102678308d750b092a 100644 (file)
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -228,7 +228,8 @@ struct tty_port {
        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 tty_port {
        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

diff --git a/include/uapi/linux/tty_flags.h b/include/uapi/linux/tty_flags.h
index 072e41e45ee220f6ce4692d3325927c5f877e0f8..8e1a4365259fb6e7366501a8be5cfde66935a367 100644 (file)
--- a/include/uapi/linux/tty_flags.h
+++ b/include/uapi/linux/tty_flags.h
@@ -32,7 +32,12 @@
 #define ASYNCB_MAGIC_MULTIPLIER        16 /* Use special CLK or divisor */
 #define ASYNCB_LAST_USER       16
 
-/* Internal flags used only by kernel */
+/*
+ * Internal flags used only by kernel (read-only)
+ *
+ * WARNING: These flags are no longer used and have been superceded by the
+ *         TTY_PORT_ flags in the iflags field (and not userspace-visible)
+ */
 #define ASYNCB_INITIALIZED     31 /* Serial port was initialized */
 #define ASYNCB_SUSPENDED       30 /* Serial port is suspended */
 #define ASYNCB_NORMAL_ACTIVE   29 /* Normal device is active */
@@ -44,6 +49,7 @@
 #define ASYNCB_CONS_FLOW       23 /* flow control for console  */
 #define ASYNCB_FIRST_KERNEL    22
 
+/* Masks */
 #define ASYNC_HUP_NOTIFY       (1U << ASYNCB_HUP_NOTIFY)
 #define ASYNC_SUSPENDED                (1U << ASYNCB_SUSPENDED)
 #define ASYNC_FOURPORT         (1U << ASYNCB_FOURPORT)
@@ -72,6 +78,7 @@
 #define ASYNC_SPD_WARP         (ASYNC_SPD_HI|ASYNC_SPD_SHI)
 #define ASYNC_SPD_MASK         (ASYNC_SPD_HI|ASYNC_SPD_VHI|ASYNC_SPD_SHI)
 
+/* These flags are no longer used (and were always masked from userspace) */
 #define ASYNC_INITIALIZED      (1U << ASYNCB_INITIALIZED)
 #define ASYNC_NORMAL_ACTIVE    (1U << ASYNCB_NORMAL_ACTIVE)
 #define ASYNC_BOOT_AUTOCONF    (1U << ASYNCB_BOOT_AUTOCONF)