From a88a69c91256418c5907c2f1f8a0ec0a36f9e6cc Mon Sep 17 00:00:00 2001 From: Joe Peterson Date: Fri, 2 Jan 2009 13:40:53 +0000 Subject: n_tty: Fix loss of echoed characters and remove bkl from n_tty Fixes the loss of echoed (and other ldisc-generated characters) when the tty is stopped or when the driver output buffer is full (happens frequently for input during continuous program output, such as ^C) and removes the Big Kernel Lock from the N_TTY line discipline. Adds an "echo buffer" to the N_TTY line discipline that handles all ldisc-generated output (including echoed characters). Along with the loss of characters, this also fixes the associated loss of sync between tty output and the ldisc state when characters cannot be immediately written to the tty driver. The echo buffer stores (in addition to characters) state operations that need to be done at the time of character output (like management of the column position). This allows echo to cooperate correctly with program output, since the ldisc state remains consistent with actual characters written. Since the echo buffer code now isolates the tty column state code to the process_out* and process_echoes functions, we can remove the Big Kernel Lock (BKL) and replace it with mutex locks. Highlights are: * Handles echo (and other ldisc output) when tty driver buffer is full - continuous program output can block echo * Saves echo when tty is in stopped state (e.g. ^S) - (e.g.: ^Q will correctly cause held characters to be released for output) * Control character pairs (e.g. "^C") are treated atomically and not split up by interleaved program output * Line discipline state is kept consistent with characters sent to the tty driver * Remove the big kernel lock (BKL) from N_TTY line discipline Signed-off-by: Joe Peterson Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index 3f4954c55e53..dfc77ded198a 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -253,6 +253,7 @@ struct tty_struct { unsigned int column; unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1; unsigned char closing:1; + unsigned char echo_overrun:1; unsigned short minimum_to_wake; unsigned long overrun_time; int num_overrun; @@ -262,11 +263,16 @@ struct tty_struct { int read_tail; int read_cnt; unsigned long read_flags[N_TTY_BUF_SIZE/(8*sizeof(unsigned long))]; + unsigned char *echo_buf; + unsigned int echo_pos; + unsigned int echo_cnt; int canon_data; unsigned long canon_head; unsigned int canon_column; struct mutex atomic_read_lock; struct mutex atomic_write_lock; + struct mutex output_lock; + struct mutex echo_lock; unsigned char *write_buf; int write_cnt; spinlock_t read_lock; -- cgit v1.2.2 From fc6f6238226e6d1248e1967eae2bf556eaf3ac17 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:43:17 +0000 Subject: pty: simplify resize We have special case logic for resizing pty/tty pairs. We also have a per driver resize method so for the pty case we should use it. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index dfc77ded198a..f88169787a5f 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -360,8 +360,7 @@ extern int tty_write_room(struct tty_struct *tty); extern void tty_driver_flush_buffer(struct tty_struct *tty); extern void tty_throttle(struct tty_struct *tty); extern void tty_unthrottle(struct tty_struct *tty); -extern int tty_do_resize(struct tty_struct *tty, struct tty_struct *real_tty, - struct winsize *ws); +extern int tty_do_resize(struct tty_struct *tty, struct winsize *ws); extern void tty_shutdown(struct tty_struct *tty); extern void tty_free_termios(struct tty_struct *tty); extern int is_current_pgrp_orphaned(void); -- cgit v1.2.2 From c9b3976e3fec266be25c5001a70aa0a890b6c476 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:44:56 +0000 Subject: tty: Fix PPP hang under load Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index f88169787a5f..bbbeaef99626 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -301,6 +301,7 @@ struct tty_struct { #define TTY_PUSH 6 /* n_tty private */ #define TTY_CLOSING 7 /* ->close() in progress */ #define TTY_LDISC 9 /* Line discipline attached */ +#define TTY_LDISC_CHANGING 10 /* Line discipline changing */ #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 */ -- cgit v1.2.2 From 31f35939d1d9bcfb3099b32c67b896d2792603f9 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:45:05 +0000 Subject: tty_port: Add a port level carrier detect operation This is the first step to generalising the various pieces of waiting logic duplicated in all sorts of serial drivers. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index bbbeaef99626..bc7bae78e22f 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -180,8 +180,16 @@ struct signal_struct; * until a hangup so don't use the wrong path. */ +struct tty_port; + +struct tty_port_operations { + /* Return 1 if the carrier is raised */ + int (*carrier_raised)(struct tty_port *port); +}; + struct tty_port { struct tty_struct *tty; /* Back pointer */ + const struct tty_port_operations *ops; /* Port operations */ spinlock_t lock; /* Lock protecting tty field */ int blocked_open; /* Waiting to open */ int count; /* Usage count */ @@ -427,6 +435,7 @@ extern int tty_port_alloc_xmit_buf(struct tty_port *port); extern void tty_port_free_xmit_buf(struct tty_port *port); 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 int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc); extern int tty_unregister_ldisc(int disc); -- cgit v1.2.2 From 5d951fb458f847e5485b5251597fbf326000bb3b Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:45:19 +0000 Subject: tty: Pull the dtr raise into tty port This moves another per device special out of what should be shared open wait paths into private methods Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index bc7bae78e22f..5001bbcacff6 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -185,6 +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); }; struct tty_port { @@ -436,6 +437,7 @@ extern void tty_port_free_xmit_buf(struct tty_port *port); 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 int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc); extern int tty_unregister_ldisc(int disc); -- cgit v1.2.2 From 3e61696bdc2103107674b06d0daf30b76193e922 Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:45:26 +0000 Subject: isicom: redo locking to use tty port locks This helps set the basis for moving block_til_ready into common code. We also introduce a tty_port_hangup helper as this will also be generally needed. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index 5001bbcacff6..a1a93140e6e4 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -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_hangup(struct tty_port *port); extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc); extern int tty_unregister_ldisc(int disc); -- cgit v1.2.2 From 36c621d82b956ff6ff72273f848af53e6c581aba Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:46:10 +0000 Subject: tty: Introduce a tty_port generic block_til_ready Start sucking more commonality out of the drivers into a single piece of core code. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- include/linux/tty.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/tty.h') diff --git a/include/linux/tty.h b/include/linux/tty.h index a1a93140e6e4..61a0ab32cf11 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -439,6 +439,8 @@ 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_hangup(struct tty_port *port); +extern int tty_port_block_til_ready(struct tty_port *port, + struct tty_struct *tty, struct file *filp); extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc); extern int tty_unregister_ldisc(int disc); -- cgit v1.2.2 From a6614999e800cf3a134ce93ea46ef837e3c0e76e Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Fri, 2 Jan 2009 13:46:50 +0000 Subject: tty: Introduce some close helpers for ports Again this is a lot of common code we can unify 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 61a0ab32cf11..fc39db95499f 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -441,6 +441,9 @@ extern void tty_port_raise_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); +extern int tty_port_close_start(struct tty_port *port, + struct tty_struct *tty, struct file *filp); +extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty); extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc); extern int tty_unregister_ldisc(int disc); -- cgit v1.2.2