linux/drivers/macintosh/windfarm_core.c
Alan Stern e041c68341 [PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe.  There is no
protection against entries being added to or removed from a chain while the
chain is in use.  The issues were discussed in this thread:

    http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2

We noticed that notifier chains in the kernel fall into two basic usage
classes:

	"Blocking" chains are always called from a process context
	and the callout routines are allowed to sleep;

	"Atomic" chains can be called from an atomic context and
	the callout routines are not allowed to sleep.

We decided to codify this distinction and make it part of the API.  Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name).  New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain.  The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.

With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed.  For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections.  (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)

There are some limitations, which should not be too hard to live with.  For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem.  Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain.  (This did happen in a couple of places and the code
had to be changed to avoid it.)

Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization.  Instead we use RCU.  The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.

Here is the list of chains that we adjusted and their classifications.  None
of them use the raw API, so for the moment it is only a placeholder.

  ATOMIC CHAINS
  -------------
arch/i386/kernel/traps.c:		i386die_chain
arch/ia64/kernel/traps.c:		ia64die_chain
arch/powerpc/kernel/traps.c:		powerpc_die_chain
arch/sparc64/kernel/traps.c:		sparc64die_chain
arch/x86_64/kernel/traps.c:		die_chain
drivers/char/ipmi/ipmi_si_intf.c:	xaction_notifier_list
kernel/panic.c:				panic_notifier_list
kernel/profile.c:			task_free_notifier
net/bluetooth/hci_core.c:		hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_expect_chain
net/ipv6/addrconf.c:			inet6addr_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_expect_chain
net/netlink/af_netlink.c:		netlink_chain

  BLOCKING CHAINS
  ---------------
arch/powerpc/platforms/pseries/reconfig.c:	pSeries_reconfig_chain
arch/s390/kernel/process.c:		idle_chain
arch/x86_64/kernel/process.c		idle_notifier
drivers/base/memory.c:			memory_chain
drivers/cpufreq/cpufreq.c		cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c		cpufreq_transition_notifier_list
drivers/macintosh/adb.c:		adb_client_list
drivers/macintosh/via-pmu.c		sleep_notifier_list
drivers/macintosh/via-pmu68k.c		sleep_notifier_list
drivers/macintosh/windfarm_core.c	wf_client_list
drivers/usb/core/notify.c		usb_notifier_list
drivers/video/fbmem.c			fb_notifier_list
kernel/cpu.c				cpu_chain
kernel/module.c				module_notify_list
kernel/profile.c			munmap_notifier
kernel/profile.c			task_exit_notifier
kernel/sys.c				reboot_notifier_list
net/core/dev.c				netdev_chain
net/decnet/dn_dev.c:			dnaddr_chain
net/ipv4/devinet.c:			inetaddr_chain

It's possible that some of these classifications are wrong.  If they are,
please let us know or submit a patch to fix them.  Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)

The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.

[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 08:44:50 -08:00

496 lines
11 KiB
C

/*
* Windfarm PowerMac thermal control. Core
*
* (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
* <benh@kernel.crashing.org>
*
* Released under the term of the GNU GPL v2.
*
* This core code tracks the list of sensors & controls, register
* clients, and holds the kernel thread used for control.
*
* TODO:
*
* Add some information about sensor/control type and data format to
* sensors/controls, and have the sysfs attribute stuff be moved
* generically here instead of hard coded in the platform specific
* driver as it us currently
*
* This however requires solving some annoying lifetime issues with
* sysfs which doesn't seem to have lifetime rules for struct attribute,
* I may have to create full features kobjects for every sensor/control
* instead which is a bit of an overkill imho
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/smp_lock.h>
#include <linux/kthread.h>
#include <linux/jiffies.h>
#include <linux/reboot.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <asm/prom.h>
#include "windfarm.h"
#define VERSION "0.2"
#undef DEBUG
#ifdef DEBUG
#define DBG(args...) printk(args)
#else
#define DBG(args...) do { } while(0)
#endif
static LIST_HEAD(wf_controls);
static LIST_HEAD(wf_sensors);
static DEFINE_MUTEX(wf_lock);
static BLOCKING_NOTIFIER_HEAD(wf_client_list);
static int wf_client_count;
static unsigned int wf_overtemp;
static unsigned int wf_overtemp_counter;
struct task_struct *wf_thread;
static struct platform_device wf_platform_device = {
.name = "windfarm",
};
/*
* Utilities & tick thread
*/
static inline void wf_notify(int event, void *param)
{
blocking_notifier_call_chain(&wf_client_list, event, param);
}
int wf_critical_overtemp(void)
{
static char * critical_overtemp_path = "/sbin/critical_overtemp";
char *argv[] = { critical_overtemp_path, NULL };
static char *envp[] = { "HOME=/",
"TERM=linux",
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
NULL };
return call_usermodehelper(critical_overtemp_path, argv, envp, 0);
}
EXPORT_SYMBOL_GPL(wf_critical_overtemp);
static int wf_thread_func(void *data)
{
unsigned long next, delay;
next = jiffies;
DBG("wf: thread started\n");
while(!kthread_should_stop()) {
try_to_freeze();
if (time_after_eq(jiffies, next)) {
wf_notify(WF_EVENT_TICK, NULL);
if (wf_overtemp) {
wf_overtemp_counter++;
/* 10 seconds overtemp, notify userland */
if (wf_overtemp_counter > 10)
wf_critical_overtemp();
/* 30 seconds, shutdown */
if (wf_overtemp_counter > 30) {
printk(KERN_ERR "windfarm: Overtemp "
"for more than 30"
" seconds, shutting down\n");
machine_power_off();
}
}
next += HZ;
}
delay = next - jiffies;
if (delay <= HZ)
schedule_timeout_interruptible(delay);
/* there should be no signal, but oh well */
if (signal_pending(current)) {
printk(KERN_WARNING "windfarm: thread got sigl !\n");
break;
}
}
DBG("wf: thread stopped\n");
return 0;
}
static void wf_start_thread(void)
{
wf_thread = kthread_run(wf_thread_func, NULL, "kwindfarm");
if (IS_ERR(wf_thread)) {
printk(KERN_ERR "windfarm: failed to create thread,err %ld\n",
PTR_ERR(wf_thread));
wf_thread = NULL;
}
}
static void wf_stop_thread(void)
{
if (wf_thread)
kthread_stop(wf_thread);
wf_thread = NULL;
}
/*
* Controls
*/
static void wf_control_release(struct kref *kref)
{
struct wf_control *ct = container_of(kref, struct wf_control, ref);
DBG("wf: Deleting control %s\n", ct->name);
if (ct->ops && ct->ops->release)
ct->ops->release(ct);
else
kfree(ct);
}
static ssize_t wf_show_control(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
s32 val = 0;
int err;
err = ctrl->ops->get_value(ctrl, &val);
if (err < 0)
return err;
return sprintf(buf, "%d\n", val);
}
/* This is really only for debugging... */
static ssize_t wf_store_control(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct wf_control *ctrl = container_of(attr, struct wf_control, attr);
int val;
int err;
char *endp;
val = simple_strtoul(buf, &endp, 0);
while (endp < buf + count && (*endp == ' ' || *endp == '\n'))
++endp;
if (endp - buf < count)
return -EINVAL;
err = ctrl->ops->set_value(ctrl, val);
if (err < 0)
return err;
return count;
}
int wf_register_control(struct wf_control *new_ct)
{
struct wf_control *ct;
mutex_lock(&wf_lock);
list_for_each_entry(ct, &wf_controls, link) {
if (!strcmp(ct->name, new_ct->name)) {
printk(KERN_WARNING "windfarm: trying to register"
" duplicate control %s\n", ct->name);
mutex_unlock(&wf_lock);
return -EEXIST;
}
}
kref_init(&new_ct->ref);
list_add(&new_ct->link, &wf_controls);
new_ct->attr.attr.name = new_ct->name;
new_ct->attr.attr.owner = THIS_MODULE;
new_ct->attr.attr.mode = 0644;
new_ct->attr.show = wf_show_control;
new_ct->attr.store = wf_store_control;
device_create_file(&wf_platform_device.dev, &new_ct->attr);
DBG("wf: Registered control %s\n", new_ct->name);
wf_notify(WF_EVENT_NEW_CONTROL, new_ct);
mutex_unlock(&wf_lock);
return 0;
}
EXPORT_SYMBOL_GPL(wf_register_control);
void wf_unregister_control(struct wf_control *ct)
{
mutex_lock(&wf_lock);
list_del(&ct->link);
mutex_unlock(&wf_lock);
DBG("wf: Unregistered control %s\n", ct->name);
kref_put(&ct->ref, wf_control_release);
}
EXPORT_SYMBOL_GPL(wf_unregister_control);
struct wf_control * wf_find_control(const char *name)
{
struct wf_control *ct;
mutex_lock(&wf_lock);
list_for_each_entry(ct, &wf_controls, link) {
if (!strcmp(ct->name, name)) {
if (wf_get_control(ct))
ct = NULL;
mutex_unlock(&wf_lock);
return ct;
}
}
mutex_unlock(&wf_lock);
return NULL;
}
EXPORT_SYMBOL_GPL(wf_find_control);
int wf_get_control(struct wf_control *ct)
{
if (!try_module_get(ct->ops->owner))
return -ENODEV;
kref_get(&ct->ref);
return 0;
}
EXPORT_SYMBOL_GPL(wf_get_control);
void wf_put_control(struct wf_control *ct)
{
struct module *mod = ct->ops->owner;
kref_put(&ct->ref, wf_control_release);
module_put(mod);
}
EXPORT_SYMBOL_GPL(wf_put_control);
/*
* Sensors
*/
static void wf_sensor_release(struct kref *kref)
{
struct wf_sensor *sr = container_of(kref, struct wf_sensor, ref);
DBG("wf: Deleting sensor %s\n", sr->name);
if (sr->ops && sr->ops->release)
sr->ops->release(sr);
else
kfree(sr);
}
static ssize_t wf_show_sensor(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct wf_sensor *sens = container_of(attr, struct wf_sensor, attr);
s32 val = 0;
int err;
err = sens->ops->get_value(sens, &val);
if (err < 0)
return err;
return sprintf(buf, "%d.%03d\n", FIX32TOPRINT(val));
}
int wf_register_sensor(struct wf_sensor *new_sr)
{
struct wf_sensor *sr;
mutex_lock(&wf_lock);
list_for_each_entry(sr, &wf_sensors, link) {
if (!strcmp(sr->name, new_sr->name)) {
printk(KERN_WARNING "windfarm: trying to register"
" duplicate sensor %s\n", sr->name);
mutex_unlock(&wf_lock);
return -EEXIST;
}
}
kref_init(&new_sr->ref);
list_add(&new_sr->link, &wf_sensors);
new_sr->attr.attr.name = new_sr->name;
new_sr->attr.attr.owner = THIS_MODULE;
new_sr->attr.attr.mode = 0444;
new_sr->attr.show = wf_show_sensor;
new_sr->attr.store = NULL;
device_create_file(&wf_platform_device.dev, &new_sr->attr);
DBG("wf: Registered sensor %s\n", new_sr->name);
wf_notify(WF_EVENT_NEW_SENSOR, new_sr);
mutex_unlock(&wf_lock);
return 0;
}
EXPORT_SYMBOL_GPL(wf_register_sensor);
void wf_unregister_sensor(struct wf_sensor *sr)
{
mutex_lock(&wf_lock);
list_del(&sr->link);
mutex_unlock(&wf_lock);
DBG("wf: Unregistered sensor %s\n", sr->name);
wf_put_sensor(sr);
}
EXPORT_SYMBOL_GPL(wf_unregister_sensor);
struct wf_sensor * wf_find_sensor(const char *name)
{
struct wf_sensor *sr;
mutex_lock(&wf_lock);
list_for_each_entry(sr, &wf_sensors, link) {
if (!strcmp(sr->name, name)) {
if (wf_get_sensor(sr))
sr = NULL;
mutex_unlock(&wf_lock);
return sr;
}
}
mutex_unlock(&wf_lock);
return NULL;
}
EXPORT_SYMBOL_GPL(wf_find_sensor);
int wf_get_sensor(struct wf_sensor *sr)
{
if (!try_module_get(sr->ops->owner))
return -ENODEV;
kref_get(&sr->ref);
return 0;
}
EXPORT_SYMBOL_GPL(wf_get_sensor);
void wf_put_sensor(struct wf_sensor *sr)
{
struct module *mod = sr->ops->owner;
kref_put(&sr->ref, wf_sensor_release);
module_put(mod);
}
EXPORT_SYMBOL_GPL(wf_put_sensor);
/*
* Client & notification
*/
int wf_register_client(struct notifier_block *nb)
{
int rc;
struct wf_control *ct;
struct wf_sensor *sr;
mutex_lock(&wf_lock);
rc = blocking_notifier_chain_register(&wf_client_list, nb);
if (rc != 0)
goto bail;
wf_client_count++;
list_for_each_entry(ct, &wf_controls, link)
wf_notify(WF_EVENT_NEW_CONTROL, ct);
list_for_each_entry(sr, &wf_sensors, link)
wf_notify(WF_EVENT_NEW_SENSOR, sr);
if (wf_client_count == 1)
wf_start_thread();
bail:
mutex_unlock(&wf_lock);
return rc;
}
EXPORT_SYMBOL_GPL(wf_register_client);
int wf_unregister_client(struct notifier_block *nb)
{
mutex_lock(&wf_lock);
blocking_notifier_chain_unregister(&wf_client_list, nb);
wf_client_count++;
if (wf_client_count == 0)
wf_stop_thread();
mutex_unlock(&wf_lock);
return 0;
}
EXPORT_SYMBOL_GPL(wf_unregister_client);
void wf_set_overtemp(void)
{
mutex_lock(&wf_lock);
wf_overtemp++;
if (wf_overtemp == 1) {
printk(KERN_WARNING "windfarm: Overtemp condition detected !\n");
wf_overtemp_counter = 0;
wf_notify(WF_EVENT_OVERTEMP, NULL);
}
mutex_unlock(&wf_lock);
}
EXPORT_SYMBOL_GPL(wf_set_overtemp);
void wf_clear_overtemp(void)
{
mutex_lock(&wf_lock);
WARN_ON(wf_overtemp == 0);
if (wf_overtemp == 0) {
mutex_unlock(&wf_lock);
return;
}
wf_overtemp--;
if (wf_overtemp == 0) {
printk(KERN_WARNING "windfarm: Overtemp condition cleared !\n");
wf_notify(WF_EVENT_NORMALTEMP, NULL);
}
mutex_unlock(&wf_lock);
}
EXPORT_SYMBOL_GPL(wf_clear_overtemp);
int wf_is_overtemp(void)
{
return (wf_overtemp != 0);
}
EXPORT_SYMBOL_GPL(wf_is_overtemp);
static int __init windfarm_core_init(void)
{
DBG("wf: core loaded\n");
/* Don't register on old machines that use therm_pm72 for now */
if (machine_is_compatible("PowerMac7,2") ||
machine_is_compatible("PowerMac7,3") ||
machine_is_compatible("RackMac3,1"))
return -ENODEV;
platform_device_register(&wf_platform_device);
return 0;
}
static void __exit windfarm_core_exit(void)
{
BUG_ON(wf_client_count != 0);
DBG("wf: core unloaded\n");
platform_device_unregister(&wf_platform_device);
}
module_init(windfarm_core_init);
module_exit(windfarm_core_exit);
MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("Core component of PowerMac thermal control");
MODULE_LICENSE("GPL");