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SubjectRe: [RESEND PATCH 2/2] PM/runtime: handle ->runtime_suspend failure correctly
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On Sunday, October 09, 2011, tom.leiming@gmail.com wrote:
> From: Ming Lei <ming.lei@canonical.com>
>
> If ->runtime_suspend returns -EAGAIN or -EBUSY, the device should
> still be in ACTIVE state, so it is not needed to send idle notification
> to its parent; if ->runtime_suspend returns other fatal failure, it
> doesn't make sense to send idle notification to its parent.
>
> So skip these when failure is returned from ->runtime_suspend, also add
> comments for this handling in rpm_suspend.
>
> This patch also updates comments for rpm_suspend:
>
> - 'Cancel a pending idle notification' should be put before, also
> should be changed as 'Cancel a pending idle notification or
> autosuspend/suspend'

That should be a different patch I think?

> - idle notification for suspend failure has been removed, so update
> comments for it
>
> Signed-off-by: Ming Lei <ming.lei@canonical.com>
> ---
> v1: some minor change on Alan's suggestion
> ---
> drivers/base/power/runtime.c | 34 +++++++++++++++++++---------------
> 1 files changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 441b5a3..e3c6a8f 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -284,14 +284,17 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev)
> * @dev: Device to suspend.
> * @rpmflags: Flag bits.
> *
> - * Check if the device's runtime PM status allows it to be suspended. If
> - * another suspend has been started earlier, either return immediately or wait
> - * for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC flags. Cancel a
> - * pending idle notification. If the RPM_ASYNC flag is set then queue a
> - * suspend request; otherwise run the ->runtime_suspend() callback directly.
> - * If a deferred resume was requested while the callback was running then carry
> - * it out; otherwise send an idle notification for the device (if the suspend
> - * failed) or for its parent (if the suspend succeeded).
> + * Check if the device's runtime PM status allows it to be suspended. Cancel
> + * a pending idle notification or autosuspend/suspend. If another suspend has
> + * been started earlier, either return immediately or wait for it to finish,
> + * depending on the RPM_NOWAIT and RPM_ASYNC flags. If the RPM_ASYNC flag is
> + * set then queue a suspend request; otherwise run the ->runtime_suspend()
> + * callback directly. If ->runtime_suspend returns failure, just cancel
> + * pending request and wake up waited tasks, then return immediatelly.
> + * After ->runtime_suspend succeeded, if a deferred resume was requested
> + * while the callback was running then carry it out; otherwise send an idle
> + * notification for its parent (if both ignore_children and irq_safe
> + * are not set).
> *
> * This function must be called under dev->power.lock with interrupts disabled.
> */
> @@ -410,15 +413,16 @@ static int rpm_suspend(struct device *dev, int rpmflags)
> dev->power.runtime_error = 0;
> else
> pm_runtime_cancel_pending(dev);
> - } else {
> + wake_up_all(&dev->power.wait_queue);
> + goto out;
> + }
> no_callback:

I don't think the change above is correct. The code below
no_callback only should be executed if retval is zero.

To achieve the goal (i.e. avoid notifying the parent if -EAGAIN or
-EBUSY is returned by the callbacks) it would be sufficient to
do parent = NULL along with resetting power.runtime_error.

> - __update_runtime_status(dev, RPM_SUSPENDED);
> - pm_runtime_deactivate_timer(dev);
> + __update_runtime_status(dev, RPM_SUSPENDED);
> + pm_runtime_deactivate_timer(dev);
>
> - if (dev->parent) {
> - parent = dev->parent;
> - atomic_add_unless(&parent->power.child_count, -1, 0);
> - }
> + if (dev->parent) {
> + parent = dev->parent;
> + atomic_add_unless(&parent->power.child_count, -1, 0);
> }
> wake_up_all(&dev->power.wait_queue);

Thanks,
Rafael


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