From fcc8ac1825d3d0fb81f73bc1a80ebc863168bb56 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Thu, 11 Jun 2009 12:24:17 +0100 Subject: tty: Add carrier processing on close to the tty_port core Some drivers implement this internally, others miss it out. Push the behaviour into the core code as that way everyone will do it consistently. Update the dtr rts method to raise or lower depending upon flags. Having a single method in this style fits most of the implementations more cleanly than two funtions. We need this in place before we tackle the USB side Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index fc39db95499f..98694364c96f 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -185,7 +185,7 @@ struct tty_port; struct tty_port_operations { /* Return 1 if the carrier is raised */ int (*carrier_raised)(struct tty_port *port); - void (*raise_dtr_rts)(struct tty_port *port); + void (*dtr_rts)(struct tty_port *port, int raise); }; struct tty_port { @@ -438,6 +438,7 @@ extern struct tty_struct *tty_port_tty_get(struct tty_port *port); extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty); extern int tty_port_carrier_raised(struct tty_port *port); extern void tty_port_raise_dtr_rts(struct tty_port *port); +extern void tty_port_lower_dtr_rts(struct tty_port *port); extern void tty_port_hangup(struct tty_port *port); extern int tty_port_block_til_ready(struct tty_port *port, struct tty_struct *tty, struct file *filp); -- cgit v1.2.3 From 1ec739be75a6cb961a46ba0b1982d0edb7f27558 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Thu, 11 Jun 2009 12:25:25 +0100 Subject: tty: Implement a drain delay in the tty port We need this for devices that cannot flush and wait, but which do not order data and modem events. Without it we will hang up before all the data clears the hardware. Needed for the USB changes. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index 98694364c96f..bed5a3d40307 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -201,6 +201,9 @@ struct tty_port { unsigned char *xmit_buf; /* Optional buffer */ int close_delay; /* Close port delay */ int closing_wait; /* Delay for output */ + int drain_delay; /* Set to zero if no pure time + based drain is needed else + set to size of fifo */ }; /* -- cgit v1.2.3 From e8b70e7d3e86319a8b2aaabde3866833d92cd80f Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Thu, 11 Jun 2009 12:48:02 +0100 Subject: tty: Extract various bits of ldisc code Before trying to tackle the ldisc bugs the code needs to be a good deal more readable, so do the simple extractions of routines first. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index bed5a3d40307..f9c13c83790c 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -428,6 +428,9 @@ extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, extern void tty_release_dev(struct file *filp); extern int tty_init_termios(struct tty_struct *tty); +extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty); +extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty); + extern struct mutex tty_mutex; extern void tty_write_unlock(struct tty_struct *tty); -- cgit v1.2.3 From c65c9bc3efa5589f691276bb9db689119a711222 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Thu, 11 Jun 2009 12:50:12 +0100 Subject: tty: rewrite the ldisc locking There are several pretty much unfixable races in the old ldisc code, especially with respect to pty behaviour and also to hangup. It's easier to rewrite the code than simply try and patch it up. This patch - splits the ldisc from the tty (so we will be able to refcount it more cleanly later) - introduces a mutex lock for ldisc changing on an active device - fixes the complete mess that hangup caused - implements hopefully correct setldisc/close/hangup locking There are still some problems around pty pairs that have always been there but at least it is now possible to understand the code and fix further problems. This fixes the following known bugs - hang up can leak ldisc references - hang up may not call open/close on ldisc in a matched way - pty/tty pairs can deadlock during an ldisc change - reading the ldisc proc files can cause every ldisc to be loaded and probably a few other of the mysterious ldisc race reports. I'm sure it also adds the odd new one. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index f9c13c83790c..1488d8c81aac 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -226,8 +226,11 @@ struct tty_struct { struct tty_driver *driver; const struct tty_operations *ops; int index; - /* The ldisc objects are protected by tty_ldisc_lock at the moment */ - struct tty_ldisc ldisc; + + /* Protects ldisc changes: Lock tty not pty */ + struct mutex ldisc_mutex; + struct tty_ldisc *ldisc; + struct mutex termios_mutex; spinlock_t ctrl_lock; /* Termios values are protected by the termios mutex */ @@ -314,6 +317,7 @@ struct tty_struct { #define TTY_CLOSING 7 /* ->close() in progress */ #define TTY_LDISC 9 /* Line discipline attached */ #define TTY_LDISC_CHANGING 10 /* Line discipline changing */ +#define TTY_LDISC_OPEN 11 /* Line discipline is open */ #define TTY_HW_COOK_OUT 14 /* Hardware can do output cooking */ #define TTY_HW_COOK_IN 15 /* Hardware can do input cooking */ #define TTY_PTY_LOCK 16 /* pty private */ @@ -406,6 +410,7 @@ extern int tty_termios_hw_change(struct ktermios *a, struct ktermios *b); extern struct tty_ldisc *tty_ldisc_ref(struct tty_struct *); extern void tty_ldisc_deref(struct tty_ldisc *); extern struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *); +extern void tty_ldisc_hangup(struct tty_struct *tty); extern const struct file_operations tty_ldiscs_proc_fops; extern void tty_wakeup(struct tty_struct *tty); -- cgit v1.2.3