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Date: Wed, 26 Feb 2014 09:40:51 -0500
From: Peter Hurley <peter@...leysoftware.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.cz>, linux-kernel@...r.kernel.org,
Peter Hurley <peter@...leysoftware.com>,
Ray Strode <halfline@...il.com>, Kay Sievers <kay@...y.org>,
David Herrmann <dh.herrmann@...il.com>,
Lennart Poettering <lennart@...ttering.net>,
Werner Fink <werner@...e.de>
Subject: [PATCH] tty: Add sysfs symlink for console name->tty device
Enable a user-space process to discover the underlying tty device
for a console, if one exists, and when the tty device is later
created or destroyed.
Add sysfs symlinks for registered consoles to their respective
devices in [sys/class,sys/devices/virtual]/tty/console.
Scan consoles at tty device (un)registration to handle deferred
console<->device (un)binding.
Reported-by: Hannes Reinecke <hare@...e.de>
Cc: Ray Strode <halfline@...il.com>
Cc: Kay Sievers <kay@...y.org>
Cc: David Herrmann <dh.herrmann@...il.com>
Cc: Lennart Poettering <lennart@...ttering.net>
Cc: Werner Fink <werner@...e.de>
Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
drivers/tty/tty_io.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/console.h | 8 +++-
kernel/printk/printk.c | 4 +-
3 files changed, 129 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index a7cdbc5..53bb141 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -169,6 +169,12 @@ static void release_tty(struct tty_struct *tty, int idx);
static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
+#define TTY_SYSFS_NOTIFY_REGISTER 0
+#define TTY_SYSFS_NOTIFY_UNREGISTER 1
+static void tty_sysfs_notify(struct tty_driver *driver, int index,
+ struct device *dev, int event);
+
+
/**
* alloc_tty_struct - allocate a tty object
*
@@ -3172,6 +3178,8 @@ struct device *tty_register_device_attr(struct tty_driver *driver,
if (retval)
goto error;
+ tty_sysfs_notify(driver, index, dev, TTY_SYSFS_NOTIFY_REGISTER);
+
return dev;
error:
@@ -3195,6 +3203,8 @@ EXPORT_SYMBOL_GPL(tty_register_device_attr);
void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
+ tty_sysfs_notify(driver, index, NULL, TTY_SYSFS_NOTIFY_UNREGISTER);
+
device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC))
@@ -3544,12 +3554,118 @@ static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
static struct device *consdev;
-void console_sysfs_notify(void)
+static void console_name(struct console *c, size_t n, char *name)
{
- if (consdev)
+ snprintf(name, n, "%s%d", c->name, c->index);
+}
+
+static struct device *console_to_tty_device(struct console *c)
+{
+ struct tty_driver *driver;
+ dev_t devt;
+ int index;
+
+ if (!c->device)
+ return NULL;
+ driver = c->device(c, &index);
+ if (!driver)
+ return NULL;
+ devt = MKDEV(driver->major, driver->minor_start) + index;
+ return class_find_device(tty_class, NULL, &devt, dev_match_devt);
+}
+
+static void symlink_console_tty_device(struct console *c)
+{
+ struct device *tty_dev;
+ char link[64];
+
+ tty_dev = console_to_tty_device(c);
+ if (tty_dev) {
+ console_name(c, sizeof(link), link);
+ sysfs_create_link_nowarn(&consdev->kobj, &tty_dev->kobj, link);
+ put_device(tty_dev);
+ }
+}
+
+static void unlink_console_tty_device(struct console *c)
+{
+ char link[64];
+
+ console_name(c, sizeof(link), link);
+ sysfs_remove_link(&consdev->kobj, link);
+}
+
+void console_sysfs_notify(struct console *console, int event)
+{
+ if (!consdev)
+ return;
+
+ switch (event) {
+ case CON_SYSFS_NOTIFY_REGISTER:
+ symlink_console_tty_device(console);
+ break;
+ case CON_SYSFS_NOTIFY_UNREGISTER:
+ unlink_console_tty_device(console);
+ break;
+ }
+
+ sysfs_notify(&consdev->kobj, NULL, "active");
+}
+
+static void tty_sysfs_notify(struct tty_driver *driver, int index,
+ struct device *dev, int event)
+{
+ struct console *c;
+ bool found_one = false;
+
+ if (!consdev)
+ return;
+
+ /* check if this tty device is a console device and if so
+ * update the sysfs console links
+ */
+ console_lock();
+ for_each_console(c) {
+ char link[64];
+ struct tty_driver *c_driver;
+ int c_index;
+
+ if (!c->device)
+ continue;
+ c_driver = c->device(c, &c_index);
+
+ if (driver == c_driver && index == c_index) {
+ console_name(c, sizeof(link), link);
+
+ switch (event) {
+ case TTY_SYSFS_NOTIFY_REGISTER:
+ sysfs_create_link_nowarn(&consdev->kobj,
+ &dev->kobj, link);
+ break;
+ case TTY_SYSFS_NOTIFY_UNREGISTER:
+ sysfs_remove_link(&consdev->kobj, link);
+ break;
+ }
+ found_one = true;
+ }
+ }
+ console_unlock();
+
+ if (found_one)
sysfs_notify(&consdev->kobj, NULL, "active");
}
+
+static void symlink_console_tty_devices(void)
+{
+ struct console *c;
+
+ console_lock();
+ for_each_console(c)
+ symlink_console_tty_device(c);
+ console_unlock();
+}
+
/*
* Ok, now we can initialize the rest of the tty devices and can count
* on memory allocations, interrupts etc..
@@ -3573,6 +3689,9 @@ int __init tty_init(void)
else
WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);
+ if (consdev)
+ symlink_console_tty_devices();
+
#ifdef CONFIG_VT
vty_init(&console_fops);
#endif
diff --git a/include/linux/console.h b/include/linux/console.h
index 7571a16..e8c4c04 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -157,10 +157,14 @@ extern int is_console_locked(void);
extern int braille_register_console(struct console *, int index,
char *console_options, char *braille_options);
extern int braille_unregister_console(struct console *);
+
+/* event values for console_sysfs_notify() */
+#define CON_SYSFS_NOTIFY_REGISTER 0
+#define CON_SYSFS_NOTIFY_UNREGISTER 1
#ifdef CONFIG_TTY
-extern void console_sysfs_notify(void);
+extern void console_sysfs_notify(struct console *, int event);
#else
-static inline void console_sysfs_notify(void)
+static inline void console_sysfs_notify(struct console *, int event)
{ }
#endif
extern bool console_suspend_enabled;
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b1d255f..1e8dbe2 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2348,7 +2348,7 @@ void register_console(struct console *newcon)
exclusive_console = newcon;
}
console_unlock();
- console_sysfs_notify();
+ console_sysfs_notify(newcon, CON_SYSFS_NOTIFY_REGISTER);
/*
* By unregistering the bootconsoles after we enable the real console
@@ -2410,7 +2410,7 @@ int unregister_console(struct console *console)
console_drivers->flags |= CON_CONSDEV;
console_unlock();
- console_sysfs_notify();
+ console_sysfs_notify(console, CON_SYSFS_NOTIFY_UNREGISTER);
return res;
}
EXPORT_SYMBOL(unregister_console);
--
1.8.1.2
--
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