| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <1190691984.27805.270.camel@localhost.localdomain>
Date: Tue, 25 Sep 2007 13:46:24 +1000
From: Rusty Russell <rusty@...tcorp.com.au>
To: Andrew Morton <akpm@...ux-foundation.org>,
lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc: Anton Blanchard <anton@....ibm.com>, paulus <paulus@....ibm.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
"Ryan S. Arnold" <rsa@...ibm.com>,
Dave Jones <davej@...emonkey.org.uk>
Subject: [PATCH] Delay creation of khcvd thread
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@...tcorp.com.au>
---
drivers/char/Kconfig | 8 ++---
drivers/char/hvc_console.c | 66 ++++++++++++++++++++++++++++++--------------
2 files changed, 49 insertions(+), 25 deletions(-)
===================================================================
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -568,10 +568,10 @@ config HVC_DRIVER
config HVC_DRIVER
bool
help
- Users of pSeries machines that want to utilize the hvc console front-end
- module for their backend console driver should select this option.
+ Generic "hypervisor virtual console" infrastructure for various
+ hypervisors (pSeries, Xen, lguest).
It will automatically be selected if one of the back-end console drivers
is selected.
config HVC_CONSOLE
===================================================================
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -68,6 +68,8 @@ 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;
@@ -754,6 +756,13 @@ struct hvc_struct __devinit *hvc_alloc(u
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_stru
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;
- }
-
- if (tty_register_driver(drv))
- panic("Couldn't register hvc console driver\n");
-
+ printk(KERN_ERR "Couldn't create kthread for console.\n");
+ err = PTR_ERR(hvc_task);
+ goto put_tty;
+ }
+
+ 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;
-}
-module_init(hvc_init);
+
+put_tty:
+ put_tty_driver(hvc_driver);
+stop_thread:
+ kthread_stop(hvc_task);
+ hvc_task = NULL;
+out:
+ return err;
+}
/* 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);
-
- tty_unregister_driver(hvc_driver);
- /* return tty_struct instances allocated in hvc_init(). */
- put_tty_driver(hvc_driver);
- unregister_console(&hvc_con_driver);
+ 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);
+ }
}
module_exit(hvc_exit);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists