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Commit e4d38f33 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 97ef38b8

include/linux/tty.h

+15 −1
Original line number Diff line number Diff line
@@ -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

include/uapi/linux/tty_flags.h

+8 −1
Original line number Diff line number Diff line
@@ -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 * WARNING: These flags are no longer used and have been superceded by the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)