From 311aab73d273eb22be976055f6cab224f7279d5e Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Mon, 8 Aug 2011 23:39:36 +0200 Subject: PM / Runtime: Add might_sleep() to runtime PM functions Some of the entry points to pm runtime are not safe to call in atomic context unless pm_runtime_irq_safe() has been called. Inspecting the code, it is not immediately obvious that the functions sleep at all, as they run inside a spin_lock_irqsave, but under some conditions they can drop the lock and turn on irqs. If a driver incorrectly calls the pm_runtime apis, it can cause sleeping and irq processing when it expects to stay in atomic context. Add might_sleep_if to the majority of the __pm_runtime_* entry points to enforce correct usage. Add pm_runtime_put_sync_autosuspend to the list of functions that can be called in atomic context. Signed-off-by: Colin Cross Reviewed-by: Kevin Hilman Signed-off-by: Rafael J. Wysocki --- drivers/base/power/runtime.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) (limited to 'drivers/base') diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index acb3f83b8079..04e18abb50bb 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -732,13 +732,16 @@ EXPORT_SYMBOL_GPL(pm_schedule_suspend); * return immediately if it is larger than zero. Then carry out an idle * notification, either synchronous or asynchronous. * - * This routine may be called in atomic context if the RPM_ASYNC flag is set. + * This routine may be called in atomic context if the RPM_ASYNC flag is set, + * or if pm_runtime_irq_safe() has been called. */ int __pm_runtime_idle(struct device *dev, int rpmflags) { unsigned long flags; int retval; + might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe); + if (rpmflags & RPM_GET_PUT) { if (!atomic_dec_and_test(&dev->power.usage_count)) return 0; @@ -761,13 +764,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_idle); * return immediately if it is larger than zero. Then carry out a suspend, * either synchronous or asynchronous. * - * This routine may be called in atomic context if the RPM_ASYNC flag is set. + * This routine may be called in atomic context if the RPM_ASYNC flag is set, + * or if pm_runtime_irq_safe() has been called. */ int __pm_runtime_suspend(struct device *dev, int rpmflags) { unsigned long flags; int retval; + might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe); + if (rpmflags & RPM_GET_PUT) { if (!atomic_dec_and_test(&dev->power.usage_count)) return 0; @@ -789,13 +795,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_suspend); * If the RPM_GET_PUT flag is set, increment the device's usage count. Then * carry out a resume, either synchronous or asynchronous. * - * This routine may be called in atomic context if the RPM_ASYNC flag is set. + * This routine may be called in atomic context if the RPM_ASYNC flag is set, + * or if pm_runtime_irq_safe() has been called. */ int __pm_runtime_resume(struct device *dev, int rpmflags) { unsigned long flags; int retval; + might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe); + if (rpmflags & RPM_GET_PUT) atomic_inc(&dev->power.usage_count); -- cgit v1.2.3-58-ga151 From ad3c36a534bc7b945d7bffdda1c62e13bf93489a Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 27 Sep 2011 21:54:52 +0200 Subject: PM / Runtime: Don't run callbacks under lock for power.irq_safe set The rpm_suspend() and rpm_resume() routines execute subsystem or PM domain callbacks under power.lock if power.irq_safe is set for the given device. This is inconsistent with that rpm_idle() does after commit 02b2677 (PM / Runtime: Allow _put_sync() from interrupts-disabled context) and is problematic for subsystems and PM domains wanting to use power.lock for synchronization in their runtime PM callbacks. This change requires the code checking if the device's runtime PM status is RPM_SUSPENDING or RPM_RESUMING to be modified too, to take the power.irq_safe set case into account (that code wasn't reachable before with power.irq_safe set, because it's executed with the device's power.lock held). Signed-off-by: Rafael J. Wysocki Reviewed-by: Ming Lei Reviewed-by: Kevin Hilman --- drivers/base/power/runtime.c | 68 ++++++++++++++++++++++++++++++-------------- 1 file changed, 46 insertions(+), 22 deletions(-) (limited to 'drivers/base') diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 04e18abb50bb..aecb2a887ed7 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -154,6 +154,31 @@ static int rpm_check_suspend_allowed(struct device *dev) return retval; } +/** + * __rpm_callback - Run a given runtime PM callback for a given device. + * @cb: Runtime PM callback to run. + * @dev: Device to run the callback for. + */ +static int __rpm_callback(int (*cb)(struct device *), struct device *dev) + __releases(&dev->power.lock) __acquires(&dev->power.lock) +{ + int retval; + + if (dev->power.irq_safe) + spin_unlock(&dev->power.lock); + else + spin_unlock_irq(&dev->power.lock); + + retval = cb(dev); + + if (dev->power.irq_safe) + spin_lock(&dev->power.lock); + else + spin_lock_irq(&dev->power.lock); + + return retval; +} + /** * rpm_idle - Notify device bus type if the device can be suspended. * @dev: Device to notify the bus type about. @@ -225,19 +250,8 @@ static int rpm_idle(struct device *dev, int rpmflags) else callback = NULL; - if (callback) { - if (dev->power.irq_safe) - spin_unlock(&dev->power.lock); - else - spin_unlock_irq(&dev->power.lock); - - callback(dev); - - if (dev->power.irq_safe) - spin_lock(&dev->power.lock); - else - spin_lock_irq(&dev->power.lock); - } + if (callback) + __rpm_callback(callback, dev); dev->power.idle_notification = false; wake_up_all(&dev->power.wait_queue); @@ -252,22 +266,14 @@ static int rpm_idle(struct device *dev, int rpmflags) * @dev: Device to run the callback for. */ static int rpm_callback(int (*cb)(struct device *), struct device *dev) - __releases(&dev->power.lock) __acquires(&dev->power.lock) { int retval; if (!cb) return -ENOSYS; - if (dev->power.irq_safe) { - retval = cb(dev); - } else { - spin_unlock_irq(&dev->power.lock); - - retval = cb(dev); + retval = __rpm_callback(cb, dev); - spin_lock_irq(&dev->power.lock); - } dev->power.runtime_error = retval; return retval != -EACCES ? retval : -EIO; } @@ -347,6 +353,15 @@ static int rpm_suspend(struct device *dev, int rpmflags) goto out; } + if (dev->power.irq_safe) { + spin_unlock(&dev->power.lock); + + cpu_relax(); + + spin_lock(&dev->power.lock); + goto repeat; + } + /* Wait for the other suspend running in parallel with us. */ for (;;) { prepare_to_wait(&dev->power.wait_queue, &wait, @@ -496,6 +511,15 @@ static int rpm_resume(struct device *dev, int rpmflags) goto out; } + if (dev->power.irq_safe) { + spin_unlock(&dev->power.lock); + + cpu_relax(); + + spin_lock(&dev->power.lock); + goto repeat; + } + /* Wait for the operation carried out in parallel with us. */ for (;;) { prepare_to_wait(&dev->power.wait_queue, &wait, -- cgit v1.2.3-58-ga151 From c3dc2f14622a06488f11452b6efd1e02c5a8548b Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 27 Sep 2011 22:54:41 +0200 Subject: PM / Runtime: Replace dev_dbg() with trace_rpm_*() This patch replaces dev_dbg with trace_rpm_* inside the three important functions: rpm_idle rpm_suspend rpm_resume Trace points have the below advantages compared with dev_dbg: - trace points include much runtime information(such as running cpu, current task, ...) - most of linux distributions may disable "verbose debug" driver debug compile switch, so it is very difficult to report/debug runtime pm related problems from distribution users without this kind of debug information. - for upstream kernel users, enableing the debug switch will produce many useless "rpm_resume" output, and it is very noise. - dev_dbg inside rpm_suspend/rpm_resume may have some effects on runtime pm behaviour of console devicer Signed-off-by: Ming Lei Acked-by: Steven Rostedt Signed-off-by: Rafael J. Wysocki --- drivers/base/power/runtime.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'drivers/base') diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index aecb2a887ed7..7a6fb5e34a0e 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -9,6 +9,7 @@ #include #include +#include #include "power.h" static int rpm_resume(struct device *dev, int rpmflags); @@ -196,6 +197,7 @@ static int rpm_idle(struct device *dev, int rpmflags) int (*callback)(struct device *); int retval; + trace_rpm_idle(dev, rpmflags); retval = rpm_check_suspend_allowed(dev); if (retval < 0) ; /* Conditions are wrong. */ @@ -257,6 +259,7 @@ static int rpm_idle(struct device *dev, int rpmflags) wake_up_all(&dev->power.wait_queue); out: + trace_rpm_return_int(dev, _THIS_IP_, retval); return retval; } @@ -301,7 +304,7 @@ static int rpm_suspend(struct device *dev, int rpmflags) struct device *parent = NULL; int retval; - dev_dbg(dev, "%s flags 0x%x\n", __func__, rpmflags); + trace_rpm_suspend(dev, rpmflags); repeat: retval = rpm_check_suspend_allowed(dev); @@ -445,7 +448,7 @@ static int rpm_suspend(struct device *dev, int rpmflags) } out: - dev_dbg(dev, "%s returns %d\n", __func__, retval); + trace_rpm_return_int(dev, _THIS_IP_, retval); return retval; } @@ -474,7 +477,7 @@ static int rpm_resume(struct device *dev, int rpmflags) struct device *parent = NULL; int retval = 0; - dev_dbg(dev, "%s flags 0x%x\n", __func__, rpmflags); + trace_rpm_resume(dev, rpmflags); repeat: if (dev->power.runtime_error) @@ -639,7 +642,7 @@ static int rpm_resume(struct device *dev, int rpmflags) spin_lock_irq(&dev->power.lock); } - dev_dbg(dev, "%s returns %d\n", __func__, retval); + trace_rpm_return_int(dev, _THIS_IP_, retval); return retval; } -- cgit v1.2.3-58-ga151