Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757404AbZLJXp1 (ORCPT ); Thu, 10 Dec 2009 18:45:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753919AbZLJXpY (ORCPT ); Thu, 10 Dec 2009 18:45:24 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:60442 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752686AbZLJXpW (ORCPT ); Thu, 10 Dec 2009 18:45:22 -0500 From: "Rafael J. Wysocki" To: Alan Stern Subject: Re: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems) Date: Fri, 11 Dec 2009 00:45:46 +0100 User-Agent: KMail/1.12.3 (Linux/2.6.32-rjw; KDE/4.3.3; x86_64; ; ) Cc: Linus Torvalds , Zhang Rui , LKML , ACPI Devel Maling List , pm list References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200912110045.46465.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12034 Lines: 425 On Thursday 10 December 2009, Alan Stern wrote: > On Thu, 10 Dec 2009, Rafael J. Wysocki wrote: > > > > You should see how badly lockdep complains about the rwsems. If it > > > really doesn't like them then using completions makes sense. > > > > It does complain about them, but when the nested _down operations are marked > > as nested, it stops complaining (that's in the version where there's no async > > in the _noirq phases). > > Did you set the async_suspend flag for any devices during the test? Yes. All ACPI, all PCI, all serio, as usual. ;-) > And did you run more than one suspend/resume cycle? Sure. Actually, I test it in the /sys/power/pm_test = core mode, but that shouldn't really matter. > > +extern int __dpm_wait(struct device *dev, void *ign); > > + > > +static inline void dpm_wait(struct device *dev) > > +{ > > + __dpm_wait(dev, NULL); > > +} > > Sorry, I intended to mention this before but forgot. This design is > inelegant. You shouldn't have inlines calling functions with extra > unused arguments; they just waste code space. Make dpm_wait() be a > real routine and add a shim to the device_for_each_child() loop. I thought about that myself, done now. > > @@ -366,7 +388,7 @@ void dpm_resume_noirq(pm_message_t state > > > > mutex_lock(&dpm_list_mtx); > > transition_started = false; > > - list_for_each_entry(dev, &dpm_list, power.entry) > > + list_for_each_entry(dev, &dpm_list, power.entry) { > > if (dev->power.status > DPM_OFF) { > > int error; > > > > @@ -375,23 +397,27 @@ void dpm_resume_noirq(pm_message_t state > > if (error) > > pm_dev_err(dev, state, " early", error); > > } > > + /* Needed by the subsequent dpm_resume(). */ > > + INIT_COMPLETION(dev->power.completion); > > You're still doing it. Don't initialize the completions in a totally > different phase! Initialize them directly before they are used. > Namely, at the start of device_resume() and device_suspend(). The idea was to initialize them all at the same time, before entering the phase in which they were used, but I came to the conclusion that this was not necessary, because the dpm_list ordering was such that the devices to be waited for would always have their completions reinitialized before starting __device_suspend() or __device_resume() for the waiting ones. > One more thing. A logical time to check for errors is just after > waiting for the children in __device_suspend(), instead of beforehand > in async_suspend(). After all, if an error occurs then it's likely to > happen while we are waiting. Good idea, done. Updated patch is appended. Rafael --- drivers/base/power/main.c | 106 ++++++++++++++++++++++++++++++++++++++++--- include/linux/device.h | 6 ++ include/linux/pm.h | 7 ++ include/linux/resume-trace.h | 7 ++ 4 files changed, 121 insertions(+), 5 deletions(-) Index: linux-2.6/include/linux/pm.h =================================================================== --- linux-2.6.orig/include/linux/pm.h +++ linux-2.6/include/linux/pm.h @@ -26,6 +26,7 @@ #include #include #include +#include /* * Callbacks for platform drivers to implement. @@ -412,9 +413,11 @@ struct dev_pm_info { pm_message_t power_state; unsigned int can_wakeup:1; unsigned int should_wakeup:1; + unsigned async_suspend:1; enum dpm_state status; /* Owned by the PM core */ #ifdef CONFIG_PM_SLEEP struct list_head entry; + struct completion completion; #endif #ifdef CONFIG_PM_RUNTIME struct timer_list suspend_timer; @@ -508,6 +511,8 @@ extern void __suspend_report_result(cons __suspend_report_result(__func__, fn, ret); \ } while (0) +extern void dpm_wait(struct device *dev); + #else /* !CONFIG_PM_SLEEP */ #define device_pm_lock() do {} while (0) @@ -520,6 +525,8 @@ static inline int dpm_suspend_start(pm_m #define suspend_report_result(fn, ret) do {} while (0) +static inline void dpm_wait(struct device *dev) {} + #endif /* !CONFIG_PM_SLEEP */ /* How to reorder dpm_list after device_move() */ Index: linux-2.6/drivers/base/power/main.c =================================================================== --- linux-2.6.orig/drivers/base/power/main.c +++ linux-2.6/drivers/base/power/main.c @@ -25,6 +25,7 @@ #include #include #include +#include #include "../base.h" #include "power.h" @@ -42,6 +43,7 @@ LIST_HEAD(dpm_list); static DEFINE_MUTEX(dpm_list_mtx); +static pm_message_t pm_transition; /* * Set once the preparation of devices for a PM transition has started, reset @@ -56,6 +58,7 @@ static bool transition_started; void device_pm_init(struct device *dev) { dev->power.status = DPM_ON; + init_completion(&dev->power.completion); pm_runtime_init(dev); } @@ -111,6 +114,7 @@ void device_pm_remove(struct device *dev pr_debug("PM: Removing info for %s:%s\n", dev->bus ? dev->bus->name : "No Bus", kobject_name(&dev->kobj)); + complete_all(&dev->power.completion); mutex_lock(&dpm_list_mtx); list_del_init(&dev->power.entry); mutex_unlock(&dpm_list_mtx); @@ -162,6 +166,28 @@ void device_pm_move_last(struct device * } /** + * dpm_wait - Wait for a PM operation to complete. + * @dev: Device to wait for. + */ +void dpm_wait(struct device *dev) +{ + if (dev) + wait_for_completion(&dev->power.completion); +} +EXPORT_SYMBOL_GPL(dpm_wait); + +static int dpm_wait_fn(struct device *dev, void *ignore) +{ + dpm_wait(dev); + return 0; +} + +static void dpm_wait_for_children(struct device *dev) +{ + device_for_each_child(dev, NULL, dpm_wait_fn); +} + +/** * pm_op - Execute the PM operation appropriate for given PM event. * @dev: Device to handle. * @ops: PM operations to choose from. @@ -381,17 +407,18 @@ void dpm_resume_noirq(pm_message_t state EXPORT_SYMBOL_GPL(dpm_resume_noirq); /** - * device_resume - Execute "resume" callbacks for given device. + * __device_resume - Execute "resume" callbacks for given device. * @dev: Device to handle. * @state: PM transition of the system being carried out. */ -static int device_resume(struct device *dev, pm_message_t state) +static int __device_resume(struct device *dev, pm_message_t state) { int error = 0; TRACE_DEVICE(dev); TRACE_RESUME(0); + dpm_wait(dev->parent); down(&dev->sem); if (dev->bus) { @@ -426,11 +453,34 @@ static int device_resume(struct device * } End: up(&dev->sem); + complete_all(&dev->power.completion); TRACE_RESUME(error); return error; } +static void async_resume(void *data, async_cookie_t cookie) +{ + struct device *dev = (struct device *)data; + int error; + + error = __device_resume(dev, pm_transition); + if (error) + pm_dev_err(dev, pm_transition, " async", error); + put_device(dev); +} + +static int device_resume(struct device *dev) +{ + if (dev->power.async_suspend && !pm_trace_is_enabled()) { + get_device(dev); + async_schedule(async_resume, dev); + return 0; + } + + return __device_resume(dev, pm_transition); +} + /** * dpm_resume - Execute "resume" callbacks for non-sysdev devices. * @state: PM transition of the system being carried out. @@ -444,6 +494,7 @@ static void dpm_resume(pm_message_t stat INIT_LIST_HEAD(&list); mutex_lock(&dpm_list_mtx); + pm_transition = state; while (!list_empty(&dpm_list)) { struct device *dev = to_device(dpm_list.next); @@ -451,10 +502,11 @@ static void dpm_resume(pm_message_t stat if (dev->power.status >= DPM_OFF) { int error; + INIT_COMPLETION(dev->power.completion); dev->power.status = DPM_RESUMING; mutex_unlock(&dpm_list_mtx); - error = device_resume(dev, state); + error = device_resume(dev); mutex_lock(&dpm_list_mtx); if (error) @@ -469,6 +521,7 @@ static void dpm_resume(pm_message_t stat } list_splice(&list, &dpm_list); mutex_unlock(&dpm_list_mtx); + async_synchronize_full(); } /** @@ -623,17 +676,23 @@ int dpm_suspend_noirq(pm_message_t state } EXPORT_SYMBOL_GPL(dpm_suspend_noirq); +static int async_error; + /** * device_suspend - Execute "suspend" callbacks for given device. * @dev: Device to handle. * @state: PM transition of the system being carried out. */ -static int device_suspend(struct device *dev, pm_message_t state) +static int __device_suspend(struct device *dev, pm_message_t state) { int error = 0; + dpm_wait_for_children(dev); down(&dev->sem); + if (async_error) + goto End; + if (dev->class) { if (dev->class->pm) { pm_dev_dbg(dev, state, "class "); @@ -666,12 +725,42 @@ static int device_suspend(struct device suspend_report_result(dev->bus->suspend, error); } } + + if (!error) + dev->power.status = DPM_OFF; + End: up(&dev->sem); + complete_all(&dev->power.completion); return error; } +static void async_suspend(void *data, async_cookie_t cookie) +{ + struct device *dev = (struct device *)data; + int error; + + error = __device_suspend(dev, pm_transition); + if (error) { + pm_dev_err(dev, pm_transition, " async", error); + async_error = error; + } + + put_device(dev); +} + +static int device_suspend(struct device *dev, pm_message_t state) +{ + if (dev->power.async_suspend) { + get_device(dev); + async_schedule(async_suspend, dev); + return 0; + } + + return __device_suspend(dev, pm_transition); +} + /** * dpm_suspend - Execute "suspend" callbacks for all non-sysdev devices. * @state: PM transition of the system being carried out. @@ -683,10 +772,12 @@ static int dpm_suspend(pm_message_t stat INIT_LIST_HEAD(&list); mutex_lock(&dpm_list_mtx); + pm_transition = state; while (!list_empty(&dpm_list)) { struct device *dev = to_device(dpm_list.prev); get_device(dev); + INIT_COMPLETION(dev->power.completion); mutex_unlock(&dpm_list_mtx); error = device_suspend(dev, state); @@ -697,13 +788,17 @@ static int dpm_suspend(pm_message_t stat put_device(dev); break; } - dev->power.status = DPM_OFF; if (!list_empty(&dev->power.entry)) list_move(&dev->power.entry, &list); put_device(dev); + if (async_error) + break; } list_splice(&list, dpm_list.prev); mutex_unlock(&dpm_list_mtx); + async_synchronize_full(); + if (!error) + error = async_error; return error; } @@ -762,6 +857,7 @@ static int dpm_prepare(pm_message_t stat INIT_LIST_HEAD(&list); mutex_lock(&dpm_list_mtx); transition_started = true; + async_error = 0; while (!list_empty(&dpm_list)) { struct device *dev = to_device(dpm_list.next); Index: linux-2.6/include/linux/resume-trace.h =================================================================== --- linux-2.6.orig/include/linux/resume-trace.h +++ linux-2.6/include/linux/resume-trace.h @@ -6,6 +6,11 @@ extern int pm_trace_enabled; +static inline int pm_trace_is_enabled(void) +{ + return pm_trace_enabled; +} + struct device; extern void set_trace_device(struct device *); extern void generate_resume_trace(const void *tracedata, unsigned int user); @@ -17,6 +22,8 @@ extern void generate_resume_trace(const #else +static inline int pm_trace_is_enabled(void) { return 0; } + #define TRACE_DEVICE(dev) do { } while (0) #define TRACE_RESUME(dev) do { } while (0) Index: linux-2.6/include/linux/device.h =================================================================== --- linux-2.6.orig/include/linux/device.h +++ linux-2.6/include/linux/device.h @@ -472,6 +472,12 @@ static inline int device_is_registered(s return dev->kobj.state_in_sysfs; } +static inline void device_enable_async_suspend(struct device *dev, bool enable) +{ + if (dev->power.status == DPM_ON) + dev->power.async_suspend = enable; +} + void driver_init(void); /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/