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Delay creation of khcvd thread

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This changes hvc_init() to be called only when someone actually uses the
hvc_console driver.  Dave Jones complained when profiling bootup.

hvc_console used to only be for Power aka pSeries: now lguest and Xen both
want it built-in in case the kernel is a guest under one of those, even
though usually it will be a native boot.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rusty Russell
2007-10-16 23:30:13 -07:00
committed by Linus Torvalds
parent fd5eea4214
commit 3e6c6f630a
2 changed files with 42 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
drivers/char/hvc_console.c
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@@ -69,6 +69,8 @@ static struct task_struct *hvc_task;
/* Picks up late kicks after list walk but before schedule() */
static int hvc_kicked;
static int hvc_init(void);
#ifdef CONFIG_MAGIC_SYSRQ
static int sysrq_pressed;
#endif
@@ -754,6 +756,13 @@ struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
struct hvc_struct *hp;
int i;
/* We wait until a driver actually comes along */
if (!hvc_driver) {
int err = hvc_init();
if (err)
return ERR_PTR(err);
}
hp = kmalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
GFP_KERNEL);
if (!hp)
@@ -829,16 +838,18 @@ int __devexit hvc_remove(struct hvc_struct *hp)
return 0;
}
/* Driver initialization. Follow console initialization. This is where the TTY
* interfaces start to become available. */
static int __init hvc_init(void)
/* Driver initialization: called as soon as someone uses hvc_alloc(). */
static int hvc_init(void)
{
struct tty_driver *drv;
int err;
/* We need more than hvc_count adapters due to hotplug additions. */
drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
if (!drv)
return -ENOMEM;
if (!drv) {
err = -ENOMEM;
goto out;
}
drv->owner = THIS_MODULE;
drv->driver_name = "hvc";
@@ -854,30 +865,43 @@ static int __init hvc_init(void)
* added later. */
hvc_task = kthread_run(khvcd, NULL, "khvcd");
if (IS_ERR(hvc_task)) {
panic("Couldn't create kthread for console.\n");
put_tty_driver(drv);
return -EIO;
printk(KERN_ERR "Couldn't create kthread for console.\n");
err = PTR_ERR(hvc_task);
goto put_tty;
}
if (tty_register_driver(drv))
panic("Couldn't register hvc console driver\n");
err = tty_register_driver(drv);
if (err) {
printk(KERN_ERR "Couldn't register hvc console driver\n");
goto stop_thread;
}
/* FIXME: This mb() seems completely random. Remove it. */
mb();
hvc_driver = drv;
return 0;
put_tty:
put_tty_driver(hvc_driver);
stop_thread:
kthread_stop(hvc_task);
hvc_task = NULL;
out:
return err;
}
module_init(hvc_init);
/* This isn't particularly necessary due to this being a console driver
* but it is nice to be thorough.
*/
static void __exit hvc_exit(void)
{
kthread_stop(hvc_task);
if (hvc_driver) {
kthread_stop(hvc_task);
tty_unregister_driver(hvc_driver);
/* return tty_struct instances allocated in hvc_init(). */
put_tty_driver(hvc_driver);
unregister_console(&hvc_con_driver);
tty_unregister_driver(hvc_driver);
/* return tty_struct instances allocated in hvc_init(). */
put_tty_driver(hvc_driver);
unregister_console(&hvc_con_driver);
}
}
module_exit(hvc_exit);