> > +/*
> > + * TTY operations open function.
> > + */
> > +static int tpk_open(struct tty_struct *tty, struct file *filp)
> > +{
> > + struct ttyprintk_port *port = &tpk_port;
>
> You can replace the rest with
>
> return tty_port_open(port, tty, filp);
> }
>
fixed
> > + * TTY operations close function.
> > + */
> > +static void tpk_close(struct tty_struct *tty, struct file *filp)
> > +{
> > + struct ttyprintk_port *port = tty->driver_data;
>
> and
> tty_port_close(port, tty, filp);
>
> > +}
>
> which saves a lot of work
>
yeah right, done
> > +
> > +/*
> > + * TTY operations write function.
> > + */
> > +int tpk_write(struct tty_struct *tty,
> > + const unsigned char *buf, int count)
> > +{
> > + struct ttyprintk_port *port;
> > + int ret;
> > +
> > + port = tty->driver_data;
> > +
> > + if (!port)
> > + return 0;
> > +
> > + if (!(port->port.flags & ASYNC_INITIALIZED))
> > + return 0;
>
> These two can't happen if you use tty_port_* so it is better to blow up.
> If you think you may be seeing it occur then use WARN_ON() or similar
>
the two checks were removed
> > +
> > + /* exclusive use of tpk_printk within this tty */
> > + mutex_lock(&port->port_write_mutex);
> > + ret = tpk_printk(buf, count);
> > + mutex_unlock(&port->port_write_mutex);
>
> And this is serialized by the caller (not that having your own lock is
> any harm)
>
own lock peserved just in case
>
> > +#define TPKRLEV (('e'<<8) | 0) /* Wait for ttyprintk ratelimiting
> > event*/
> > +static int tpk_ioctl(struct tty_struct *tty, struct file *file,
> > + unsigned int cmd, unsigned long arg)
> > +{
> > + struct ttyprintk_port *port;
> > +
> > + port = tty->driver_data;
> > +
> > + if (!port)
> > + return -EINVAL;
> > +
> > + switch (cmd) {
> > + case TPKRLEV:
> > + wait_event_interruptible(ttyprintk_ratelimit_wq,
> > + (ttyprintk_ratelimit_event != 0));
>
> Ok that wasn't quite what I had in mind.
ratelimiting remained present
>
> What I was thinking was needed was this
>
> /* Stop TIOCCONS */
> case TIOCCONS:
> return -EOPNOTSUPP;
>
added
> only it won't work that way. I'll sort that out in tty_io.c once the
> driver is happy. That way anything trying to mis-redirect the console
> will get stopped early which is probably more reliable than a ratelimit ?
>
> > + memset(&tpk_port, 0, sizeof(tpk_port));
>
memset removed
> It's static so that isn't needed
>
> > + tty_port_init(&tpk_port.port);
> > + spin_lock_init(&tpk_port.lock);
>
> The one other bit you will need to use the helpers is
>
> struct tty_port_operations null_ops = { };
>
> tpk_port.port->ops = &null_ops;
>
> Alan
Also added, with many thanks,
Samo
----
Signed-off-by: Samo Pogacnik <samo_pogac...@t-2.net>
diff --git a_linux/Documentation/devices.txt b_linux/Documentation/devices.txt
index 53d64d3..71aef33 100644
--- a_linux/Documentation/devices.txt
+++ b_linux/Documentation/devices.txt
@@ -239,6 +239,7 @@ Your cooperation is appreciated.
0 = /dev/tty Current TTY device
1 = /dev/console System console
2 = /dev/ptmx PTY master multiplex
+ 3 = /dev/ttyprintk User messages via printk TTY device
64 = /dev/cua0 Callout device for ttyS0
...
255 = /dev/cua191 Callout device for ttyS191
diff --git a_linux/drivers/char/Kconfig b_linux/drivers/char/Kconfig
index 3141dd3..5c38a06 100644
--- a_linux/drivers/char/Kconfig
+++ b_linux/drivers/char/Kconfig
@@ -485,6 +485,20 @@ config LEGACY_PTY_COUNT
When not in use, each legacy PTY occupies 12 bytes on 32-bit
architectures and 24 bytes on 64-bit architectures.
+config TTY_PRINTK
+ bool "TTY driver to output user messages via printk"
+ default n
+ ---help---
+ If you say Y here, the support for writing user messages (i.e.
+ console messages) via printk is available.
+
+ The feature is useful to inline user messages with kernel
+ messages.
+ In order to use this feature, you should output user messages
+ to /dev/ttyprintk or redirect console to this TTY.
+
+ If unsure, say N.
+
config BRIQ_PANEL
tristate 'Total Impact briQ front panel driver'
depends on PPC_CHRP
diff --git a_linux/drivers/char/Makefile b_linux/drivers/char/Makefile
index f957edf..ed60f45 100644
--- a_linux/drivers/char/Makefile
+++ b_linux/drivers/char/Makefile
@@ -11,6 +11,7 @@ obj-y += mem.o random.o tty_io.o n_tty.o tty_ioctl.o
tty_ldisc.o tty_buffer.o t
obj-$(CONFIG_LEGACY_PTYS) += pty.o
obj-$(CONFIG_UNIX98_PTYS) += pty.o
+obj-$(CONFIG_TTY_PRINTK) += ttyprintk.o
obj-y += misc.o
obj-$(CONFIG_VT) += vt_ioctl.o vc_screen.o selection.o keyboard.o
obj-$(CONFIG_BFIN_JTAG_COMM) += bfin_jtag_comm.o
diff --git a_linux/drivers/char/ttyprintk.c b_linux/drivers/char/ttyprintk.c
new file mode 100644
index 0000000..333490d
--- /dev/null
+++ b_linux/drivers/char/ttyprintk.c
@@ -0,0 +1,248 @@
+/*
+ * linux/drivers/char/ttyprintk.c
+ *
+ * Copyright (C) 2010 Samo Pogacnik
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the smems of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ */
+
+/*
+ * This pseudo device allows user to make printk messages. It is possible
+ * to store "console" messages inline with kernel messages for better analyses
+ * of the boot process, for example.
+ */
+
+#include <linux/sched.h>
+#include <linux/ratelimit.h>
+#include <linux/device.h>
+#include <linux/serial.h>
+#include <linux/tty.h>
+
+/*
+ * Ratelimiting support to handle to much output to this device,
+ * because of explicit writes or because of unintentional recursive
+ * setup (caught printks again sent to this device).
+ */
+static struct ratelimit_state ttyprintk_rs = {
+ .interval = DEFAULT_RATELIMIT_INTERVAL,
+ .burst = DEFAULT_RATELIMIT_BURST,
+};
+
+/*
+ * Ratelimiting action and notification support
+ */
+static DECLARE_WAIT_QUEUE_HEAD(ttyprintk_ratelimit_wq);
+static int ttyprintk_ratelimit_event;
+
+#define ttyprintk_ratelimited(fmt, ...) \
+{ \
+ if (__ratelimit(&ttyprintk_rs)) { \
+ ttyprintk_ratelimit_event = 0; \
+ printk(KERN_INFO fmt, ##__VA_ARGS__); \
+ } else { \
+ ttyprintk_ratelimit_event = 1; \
+ wake_up_all(&ttyprintk_ratelimit_wq); \
+ } \
+}
+
+/*
+ * Our simple preformatting supports transparent output of (time-stamped)
+ * printk messages (also suitable for logging service):
+ * - any cr is replaced by nl
+ * - adds a ttyprintk source tag in front of each line
+ * - too long message is fragmeted, with '\'nl between fragments
+ */
+static const char *tpk_tag = "[U] "; /* U for User */
+#define TTY_PRINTK_STR_SIZE 508
+
+static int tpk_printk(const unsigned char *buf, int count)
+{
+ static char tmp[TTY_PRINTK_STR_SIZE + 4];
+ static int curr;
+ int i;
+
+ for (i = 0; i < count; i++) {
+ tmp[curr] = buf[i];
+ if (curr < TTY_PRINTK_STR_SIZE) {
+ switch (buf[i]) {
+ case '\r':
+ /* replace cr with nl */
+ tmp[curr + 0] = '\n';
+ tmp[curr + 1] = '\0';
+ ttyprintk_ratelimited("%s%s", tpk_tag, tmp);
+ curr = 0;
+ if (buf[i + 1] == '\n')
+ i++;
+ break;
+ case '\n':
+ tmp[curr + 1] = '\0';
+ ttyprintk_ratelimited("%s%s", tpk_tag, tmp);
+ curr = 0;
+ break;
+ default:
+ curr++;
+ }
+ } else {
+ /* end of tmp buffer reached: cut the message in two */
+ tmp[curr + 1] = '\\';
+ tmp[curr + 2] = '\n';
+ tmp[curr + 3] = '\0';
+ ttyprintk_ratelimited("%s%s", tpk_tag, tmp);
+ curr = 0;
+ }
+ }
+ if (curr > 0) {
+ /* non nl or cr terminated message - add nl */
+ tmp[curr + 0] = '\n';
+ tmp[curr + 1] = '\0';
+ ttyprintk_ratelimited("%s%s", tpk_tag, tmp);
+ curr = 0;
+ }
+
+ return count;
+}
+
+struct ttyprintk_port {
+ struct tty_port port;
+ struct mutex port_write_mutex;
+};
+
+static struct ttyprintk_port tpk_port;
+
+/*
+ * TTY operations open function.
+ */
+static int tpk_open(struct tty_struct *tty, struct file *filp)
+{
+ tty->driver_data = &tpk_port;
+
+ return tty_port_open(&tpk_port.port, tty, filp);
+}
+
+/*
+ * TTY operations close function.
+ */
+static void tpk_close(struct tty_struct *tty, struct file *filp)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+
+ tty_port_close(&tpkp->port, tty, filp);
+}
+
+/*
+ * TTY operations write function.
+ */
+int tpk_write(struct tty_struct *tty,
+ const unsigned char *buf, int count)
+{
+ struct ttyprintk_port *tpkp = tty->driver_data;
+ int ret;
+
+ /* exclusive use of tpk_printk within this tty */
+ mutex_lock(&tpkp->port_write_mutex);
+ ret = tpk_printk(buf, count);
+ mutex_unlock(&tpkp->port_write_mutex);
+
+ return ret;
+}
+
+/*
+ * TTY operations write_room function.
+ */
+int tpk_write_room(struct tty_struct *tty)
+{
+ return TTY_PRINTK_STR_SIZE;
+}
+
+/*
+ * TTY operations ioctl function.
+ */
+#define TPKRLEV (('e'<<8) | 0) /* Wait for ttyprintk ratelimiting
event*/
+static int tpk_ioctl(struct tty_struct *tty, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct ttyprintk_port *port;
+
+ port = tty->driver_data;
+
+ if (!port)
+ return -EINVAL;
+
+ switch (cmd) {
+ /* Catch ratelimiting activation */
+ case TPKRLEV:
+ wait_event_interruptible(ttyprintk_ratelimit_wq,
+ (ttyprintk_ratelimit_event != 0));
+ break;
+ /* Stop TIOCCONS */
+ case TIOCCONS:
+ return -EOPNOTSUPP;
+ default:
+ return -ENOIOCTLCMD;
+ }
+ return 0;
+}
+
+static const struct tty_operations ttyprintk_ops = {
+ .open = tpk_open,
+ .close = tpk_close,
+ .write = tpk_write,
+ .write_room = tpk_write_room,
+ .ioctl = tpk_ioctl,
+};
+
+struct tty_port_operations null_ops = { };
+
+static struct tty_driver *ttyprintk_driver;
+
+static int __init ttyprintk_init(void)
+{
+ int ret = -ENOMEM;
+ void *rp;
+
+ ttyprintk_driver = alloc_tty_driver(1);
+ if (!ttyprintk_driver)
+ return ret;
+
+ ttyprintk_driver->owner = THIS_MODULE;
+ ttyprintk_driver->driver_name = "ttyprintk";
+ ttyprintk_driver->name = "ttyprintk";
+ ttyprintk_driver->major = TTYAUX_MAJOR;
+ ttyprintk_driver->minor_start = 3;
+ ttyprintk_driver->num = 1;
+ ttyprintk_driver->type = TTY_DRIVER_TYPE_CONSOLE;
+ ttyprintk_driver->init_termios = tty_std_termios;
+ ttyprintk_driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
+ ttyprintk_driver->flags = TTY_DRIVER_RESET_TERMIOS |
+ TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
+ tty_set_operations(ttyprintk_driver, &ttyprintk_ops);
+
+ ret = tty_register_driver(ttyprintk_driver);
+ if (ret < 0) {
+ printk(KERN_ERR "Couldn't register ttyprintk driver\n");
+ goto error;
+ }
+
+ /* create our unnumbered device */
+ rp = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 3), NULL,
+ ttyprintk_driver->name);
+ if (IS_ERR(rp)) {
+ printk(KERN_ERR "Couldn't create ttyprintk device\n");
+ ret = PTR_ERR(rp);
+ goto error;
+ }
+
+ tty_port_init(&tpk_port.port);
+ tpk_port.port.ops = &null_ops;
+ mutex_init(&tpk_port.port_write_mutex);
+
+ return 0;
+
+error:
+ put_tty_driver(ttyprintk_driver);
+ ttyprintk_driver = NULL;
+ return ret;
+}
+module_init(ttyprintk_init);
--
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