Re: [PATCH 2/2] Fix console handling during suspend/resume

Linus Torvalds
2006-06-24T22:28:33Z

On Sat, 24 Jun 2006, Alan Stern wrote:
>
> > - "suspend_prepare()" is called for every device (with the semaphore
> > held, you are _not_ allowed to try to unlink yourself in the prepare
> > function)
>
> There should be a big fat warning about this somewhere, maybe added to the
> documentation.

Well, there is, right now, above the only place that does this (ie the
function itself).

Anyway, would people object to merging the infrastructure work early, even
if nothing else actually was done before 2.6.18?

As it stands now, the infrastructure work really shouldn't change any
existing use (modulo bugs, of course), and I'd expect it to suspend and
resume as well (or badly) as it ever has.

Actually using suspend_late()/resume_early() runs into issues with the
"platform_device" also needing to be taught about the thing, and it's
already too late in the 2.6.18 series to even really try, but I'd like to
have the infrastructure all in place, and I don't think anybody really
_disagreed_ with the patch per se.

Which is not to say that we might not do more work on the
"suspend_prepare" (and the currently unimplemented "resume_finish" side).

In fact, the current limitation of "suspend_prepare()" would go away if we
took the same approach as the other suspend phases do: move devices one by
one onto a separate list, and have the "resume_finish()" code then move
them back.

Does anybody _hate_ this approach?

I'm re-attaching the patch here. It's identical to the previous version,
except slightly updated for the current kernel top-of-tree (which has the
TRACE_RESUME() code merged in).

Linus

---
commit 62421a15a797a0e7a083b9e11d890c54a5306e10
Author: Linus Torvalds <torvalds@macmini.osdl.org>
Date: Sat Jun 24 14:50:29 2006 -0700

Suspend infrastructure cleanup and extension

Allow devices to participate in the suspend process more intimately,
in particular, allow the final phase (with interrupts disabled) to
also be open to normal devices, not just system devices.

Also, allow classes to participate in device suspend.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/base/power/resume.c b/drivers/base/power/resume.c
index 520679c..6470fd1 100644
--- a/drivers/base/power/resume.c
+++ b/drivers/base/power/resume.c
@@ -38,13 +38,35 @@ int resume_device(struct device * dev)
dev_dbg(dev,"resuming\n");
error = dev->bus->resume(dev);
}
+ if (dev->class && dev->class->resume) {
+ dev_dbg(dev,"class resume\n");
+ error = dev->class->resume(dev);
+ }
up(&dev->sem);
TRACE_RESUME(error);
return error;
}

+static int resume_device_early(struct device * dev)
+{
+ int error = 0;
+
+ TRACE_DEVICE(dev);
+ TRACE_RESUME(0);
+ if (dev->bus && dev->bus->resume_early) {
+ dev_dbg(dev,"EARLY resume\n");
+ error = dev->bus->resume(dev);
+ }
+ TRACE_RESUME(error);
+ return error;
+}

+/*
+ * Resume the devices that have either not gone through
+ * the late suspend, or that did go through it but also
+ * went through the early resume
+ */
void dpm_resume(void)
{
down(&dpm_list_sem);
@@ -100,11 +122,9 @@ void dpm_power_up(void)
struct list_head * entry = dpm_off_irq.next;
struct device * dev = to_device(entry);

- get_device(dev);
list_del_init(entry);
- list_add_tail(entry, &dpm_active);
- resume_device(dev);
- put_device(dev);
+ list_add_tail(entry, &dpm_off);
+ resume_device_early(dev);
}
}

diff --git a/drivers/base/power/suspend.c b/drivers/base/power/suspend.c
index 1a1fe43..2e6be8a 100644
--- a/drivers/base/power/suspend.c
+++ b/drivers/base/power/suspend.c
@@ -65,7 +65,19 @@ int suspend_device(struct device * dev,

dev->power.prev_state = dev->power.power_state;

- if (dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
+ if (dev->class && dev->class->suspend && !dev->power.power_state.event) {
+ dev_dbg(dev, "class %s%s\n",
+ suspend_verb(state.event),
+ ((state.event == PM_EVENT_SUSPEND)
+ && device_may_wakeup(dev))
+ ? ", may wakeup"
+ : ""
+ );
+ error = dev->class->suspend(dev, state);
+ suspend_report_result(dev->class->suspend, error);
+ }
+
+ if (!error && dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
dev_dbg(dev, "%s%s\n",
suspend_verb(state.event),
((state.event == PM_EVENT_SUSPEND)
@@ -81,15 +93,74 @@ int suspend_device(struct device * dev,
}

+/*
+ * This is called with interrupts off, only a single CPU
+ * running. We can't do down() on a semaphore (and we don't
+ * need the protection)
+ */
+static int suspend_device_late(struct device *dev, pm_message_t state)
+{
+ int error = 0;
+
+ if (dev->power.power_state.event) {
+ dev_dbg(dev, "PM: suspend_late %d-->%d\n",
+ dev->power.power_state.event, state.event);
+ }
+
+ if (dev->bus && dev->bus->suspend_late && !dev->power.power_state.event) {
+ dev_dbg(dev, "LATE %s%s\n",
+ suspend_verb(state.event),
+ ((state.event == PM_EVENT_SUSPEND)
+ && device_may_wakeup(dev))
+ ? ", may wakeup"
+ : ""
+ );
+ error = dev->bus->suspend_late(dev, state);
+ suspend_report_result(dev->bus->suspend_late, error);
+ }
+ return error;
+}
+
+/**
+ * device_prepare_suspend - save state and prepare to suspend
+ *
+ * NOTE! Devices cannot detach at this point - not only do we
+ * hold the device list semaphores over the whole prepare, but
+ * the whole point is to do non-invasive preparatory work, not
+ * the actual suspend.
+ */
+int device_prepare_suspend(pm_message_t state)
+{
+ int error = 0;
+ struct device * dev;
+
+ down(&dpm_sem);
+ down(&dpm_list_sem);
+ list_for_each_entry_reverse(dev, &dpm_active, power.entry) {
+ if (!dev->bus || !dev->bus->suspend_prepare)
+ continue;
+ error = dev->bus->suspend_prepare(dev, state);
+ if (error)
+ break;
+ }
+ up(&dpm_list_sem);
+ up(&dpm_sem);
+ return error;
+}
+
/**
* device_suspend - Save state and stop all devices in system.
* @state: Power state to put each device in.
*
* Walk the dpm_active list, call ->suspend() for each device, and move
- * it to dpm_off.
- * Check the return value for each. If it returns 0, then we move the
- * the device to the dpm_off list. If it returns -EAGAIN, we move it to
- * the dpm_off_irq list. If we get a different error, try and back out.
+ * it to the dpm_off list.
+ *
+ * (For historical reasons, if it returns -EAGAIN, that used to mean
+ * that the device would be called again with interrupts enabled.
+ * These days, we use the "suspend_late()" callback for that, so we
+ * print a warning and consider it an error).
+ *
+ * If we get a different error, try and back out.
*
* If we hit a failure with any of the devices, call device_resume()
* above to bring the suspended devices back to life.
@@ -115,42 +186,29 @@ int device_suspend(pm_message_t state)

/* Check if the device got removed */
if (!list_empty(&dev->power.entry)) {
- /* Move it to the dpm_off or dpm_off_irq list */
+ /* Move it to the dpm_off_irq list */
if (!error) {
list_del(&dev->power.entry);
list_add(&dev->power.entry, &dpm_off);
- } else if (error == -EAGAIN) {
- list_del(&dev->power.entry);
- list_add(&dev->power.entry, &dpm_off_irq);
- error = 0;
}
}
if (error)
printk(KERN_ERR "Could not suspend device %s: "
- "error %d\n", kobject_name(&dev->kobj), error);
+ "error %d%s\n",
+ kobject_name(&dev->kobj), error,
+ error == -EAGAIN ? " (please convert to suspend_late)" : "");
put_device(dev);
}
up(&dpm_list_sem);
- if (error) {
- /* we failed... before resuming, bring back devices from
- * dpm_off_irq list back to main dpm_off list, we do want
- * to call resume() on them, in case they partially suspended
- * despite returning -EAGAIN
- */
- while (!list_empty(&dpm_off_irq)) {
- struct list_head * entry = dpm_off_irq.next;
- list_del(entry);
- list_add(entry, &dpm_off);
- }
+ if (error)
dpm_resume();
- }
+
up(&dpm_sem);
return error;
}

EXPORT_SYMBOL_GPL(device_suspend);

-
/**
* device_power_down - Shut down special devices.
* @state: Power state to enter.
@@ -165,14 +223,18 @@ int device_power_down(pm_message_t state
int error = 0;
struct device * dev;

- list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
- if ((error = suspend_device(dev, state)))
- break;
+ while (!list_empty(&dpm_off)) {
+ struct list_head * entry = dpm_off.prev;
+
+ dev = to_device(entry);
+ error = suspend_device_late(dev, state);
+ if (error)
+ goto Error;
+ list_del(&dev->power.entry);
+ list_add(&dev->power.entry, &dpm_off_irq);
}
- if (error)
- goto Error;
- if ((error = sysdev_suspend(state)))
- goto Error;
+
+ error = sysdev_suspend(state);
Done:
return error;
Error:
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 10e1a90..6308fed 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -265,6 +265,19 @@ static int pci_device_remove(struct devi
return 0;
}

+static int pci_device_suspend_prepare(struct device * dev, pm_message_t state)
+{
+ struct pci_dev * pci_dev = to_pci_dev(dev);
+ struct pci_driver * drv = pci_dev->driver;
+ int i = 0;
+
+ if (drv && drv->suspend_prepare) {
+ i = drv->suspend_prepare(pci_dev, state);
+ suspend_report_result(drv->suspend_prepare, i);
+ }
+ return i;
+}
+
static int pci_device_suspend(struct device * dev, pm_message_t state)
{
struct pci_dev * pci_dev = to_pci_dev(dev);
@@ -280,6 +293,18 @@ static int pci_device_suspend(struct dev
return i;
}

+static int pci_device_suspend_late(struct device * dev, pm_message_t state)
+{
+ struct pci_dev * pci_dev = to_pci_dev(dev);
+ struct pci_driver * drv = pci_dev->driver;
+ int i = 0;
+
+ if (drv && drv->suspend_late) {
+ i = drv->suspend_late(pci_dev, state);
+ suspend_report_result(drv->suspend_late, i);
+ }
+ return i;
+}

/*
* Default resume method for devices that have no driver provided resume,
@@ -314,6 +339,17 @@ static int pci_device_resume(struct devi
return error;
}

+static int pci_device_resume_early(struct device * dev)
+{
+ int error = 0;
+ struct pci_dev * pci_dev = to_pci_dev(dev);
+ struct pci_driver * drv = pci_dev->driver;
+
+ if (drv && drv->resume_early)
+ error = drv->resume_early(pci_dev);
+ return error;
+}
+
static void pci_device_shutdown(struct device *dev)
{
struct pci_dev *pci_dev = to_pci_dev(dev);
@@ -509,9 +545,12 @@ struct bus_type pci_bus_type = {
.uevent = pci_uevent,
.probe = pci_device_probe,
.remove = pci_device_remove,
+ .suspend_prepare= pci_device_suspend_prepare,
.suspend = pci_device_suspend,
- .shutdown = pci_device_shutdown,
+ .suspend_late = pci_device_suspend_late,
+ .resume_early = pci_device_resume_early,
.resume = pci_device_resume,
+ .shutdown = pci_device_shutdown,
.dev_attrs = pci_dev_attrs,
};

diff --git a/include/linux/device.h b/include/linux/device.h
index 1e5f30d..99d2a18 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -51,8 +51,12 @@ struct bus_type {
int (*probe)(struct device * dev);
int (*remove)(struct device * dev);
void (*shutdown)(struct device * dev);
- int (*suspend)(struct device * dev, pm_message_t state);
- int (*resume)(struct device * dev);
+
+ int (*suspend_prepare)(struct device * dev, pm_message_t state);
+ int (*suspend)(struct device * dev, pm_message_t state);
+ int (*suspend_late)(struct device * dev, pm_message_t state);
+ int (*resume_early)(struct device * dev);
+ int (*resume)(struct device * dev);
};

extern int bus_register(struct bus_type * bus);
@@ -154,6 +158,9 @@ struct class {

void (*release)(struct class_device *dev);
void (*class_release)(struct class *class);
+
+ int (*suspend)(struct device *, pm_message_t state);
+ int (*resume)(struct device *);
};

extern int class_register(struct class *);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 62a8c22..9a762c8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -344,7 +344,10 @@ struct pci_driver {
const struct pci_device_id *id_table; /* must be non-NULL for probe to be called */
int (*probe) (struct pci_dev *dev, const struct pci_device_id *id); /* New device inserted */
void (*remove) (struct pci_dev *dev); /* Device removed (NULL if not a hot-plug capable driver) */
+ int (*suspend_prepare) (struct pci_dev *dev, pm_message_t state);
int (*suspend) (struct pci_dev *dev, pm_message_t state); /* Device suspended */
+ int (*suspend_late) (struct pci_dev *dev, pm_message_t state);
+ int (*resume_early) (struct pci_dev *dev);
int (*resume) (struct pci_dev *dev); /* Device woken up */
int (*enable_wake) (struct pci_dev *dev, pci_power_t state, int enable); /* Enable wake event */
void (*shutdown) (struct pci_dev *dev);
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 658c1b9..096fb6f 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -190,6 +190,7 @@ #ifdef CONFIG_PM
extern suspend_disk_method_t pm_disk_mode;

extern int device_suspend(pm_message_t state);
+extern int device_prepare_suspend(pm_message_t state);

#define device_set_wakeup_enable(dev,val) \
((dev)->power.should_wakeup = !!(val))
diff --git a/kernel/power/main.c b/kernel/power/main.c
index cdf0f07..18a0f91 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -57,6 +57,10 @@ static int suspend_prepare(suspend_state
if (!pm_ops || !pm_ops->enter)
return -EPERM;

+ error = device_prepare_suspend(PMSG_SUSPEND);
+ if (error)
+ return error;
+
pm_prepare_console();

disable_nonboot_cpus();