Re: [PATCH 097/105] libata-acpi: add back ACPI based hotplug functionality

[Aaron Lu <aaron.lu@intel.com>]

On 06/29/2013 02:51 AM, Kamal Mostafa wrote:
> 3.8.13.4 -stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Aaron Lu <aaron.lu@intel.com>
> 
> commit 44521527be36172864e6e7a6fba4b66e9aa48e40 upstream.
> 
> Commit 30dcf76acc69 "libata: migrate ACPI code over to new bindings"
> mistakenly dropped the code to register hotplug notificaion handler
> for ATA port/devices, causing regression for people using ATA bay,
> as kernel bug #59871 shows.
> 
> Fix this by adding back the hotplug notification handler registration
> code.  Since this code has to be run once and notification needs to
> be installed on every ATA port/devices handle no matter if there is
> actual device attached, we can't do this in binding time for ATA
> device ACPI handle, as the binding only occurs when a SCSI device is
> created, i.e. there is device attached.  So introduce the
> ata_acpi_hotplug_init() function to loop scan all ATA ACPI handles
> and if it is available, install the notificaion handler for it during
> ATA init time.
> 
> With the ATA ACPI handle binding to SCSI device tree, it is possible
> now that when the SCSI hotplug work removes the SCSI device, the ACPI
> unbind function will find that the corresponding ACPI device has
> already been deleted by dock driver, causing a scaring message like:
> [  128.263966] scsi 4:0:0:0: Oops, 'acpi_handle' corrupt
> Fix this by waiting for SCSI hotplug task finish in our notificaion
> handler, so that the removal of ACPI device done in ACPI unbind
> function triggered by the removal of SCSI device is run earlier when
> ACPI device is still available.
> 
> [rjw: Rebased]
> References: https://bugzilla.kernel.org/show_bug.cgi?id=59871
> Reported-bisected-and-tested-by: Dirk Griesbach <spamthis@freenet.de>
> Signed-off-by: Aaron Lu <aaron.lu@intel.com>
> Acked-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> [ kamal: backport to 3.8 ]

Cool, thanks for the backport, I should have noticed this change of API.
I'll be more careful next time. BTW, the backport looks good to me.

Thanks,
Aaron

> Signed-off-by: Kamal Mostafa <kamal@canonical.com>
> ---
>  drivers/ata/libata-acpi.c | 36 +++++++++++++++++++++++++++++++++++-
>  drivers/ata/libata-core.c |  2 ++
>  drivers/ata/libata.h      |  2 ++
>  3 files changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
> index cc8aa9e..4cdeee4 100644
> --- a/drivers/ata/libata-acpi.c
> +++ b/drivers/ata/libata-acpi.c
> @@ -156,8 +156,10 @@ static void ata_acpi_handle_hotplug(struct ata_port *ap, struct ata_device *dev,
>  
>  	spin_unlock_irqrestore(ap->lock, flags);
>  
> -	if (wait)
> +	if (wait) {
>  		ata_port_wait_eh(ap);
> +		flush_work(&ap->hotplug_task.work);
> +	}
>  }
>  
>  static void ata_acpi_dev_notify_dock(acpi_handle handle, u32 event, void *data)
> @@ -214,6 +216,38 @@ static const struct acpi_dock_ops ata_acpi_ap_dock_ops = {
>  	.uevent = ata_acpi_ap_uevent,
>  };
>  
> +void ata_acpi_hotplug_init(struct ata_host *host)
> +{
> +	int i;
> +
> +	for (i = 0; i < host->n_ports; i++) {
> +		struct ata_port *ap = host->ports[i];
> +		acpi_handle handle;
> +		struct ata_device *dev;
> +
> +		if (!ap)
> +			continue;
> +
> +		handle = ata_ap_acpi_handle(ap);
> +		if (handle) {
> +			/* we might be on a docking station */
> +			register_hotplug_dock_device(handle,
> +						     &ata_acpi_ap_dock_ops, ap);
> +		}
> +
> +		ata_for_each_dev(dev, &ap->link, ALL) {
> +			handle = ata_dev_acpi_handle(dev);
> +			if (!handle)
> +				continue;
> +
> +			/* we might be on a docking station */
> +			register_hotplug_dock_device(handle,
> +						     &ata_acpi_dev_dock_ops,
> +						     dev);
> +		}
> +	}
> +}
> +
>  /**
>   * ata_acpi_dissociate - dissociate ATA host from ACPI objects
>   * @host: target ATA host
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 3b3afa8..5866bf5 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -6124,6 +6124,8 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
>  	if (rc)
>  		goto err_tadd;
>  
> +	ata_acpi_hotplug_init(host);
> +
>  	/* set cable, sata_spd_limit and report */
>  	for (i = 0; i < host->n_ports; i++) {
>  		struct ata_port *ap = host->ports[i];
> diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
> index 7148a58..15ac13f 100644
> --- a/drivers/ata/libata.h
> +++ b/drivers/ata/libata.h
> @@ -122,6 +122,7 @@ extern int ata_acpi_register(void);
>  extern void ata_acpi_unregister(void);
>  extern void ata_acpi_bind(struct ata_device *dev);
>  extern void ata_acpi_unbind(struct ata_device *dev);
> +extern void ata_acpi_hotplug_init(struct ata_host *host);
>  #else
>  static inline void ata_acpi_dissociate(struct ata_host *host) { }
>  static inline int ata_acpi_on_suspend(struct ata_port *ap) { return 0; }
> @@ -134,6 +135,7 @@ static inline int ata_acpi_register(void) { return 0; }
>  static inline void ata_acpi_unregister(void) { }
>  static inline void ata_acpi_bind(struct ata_device *dev) { }
>  static inline void ata_acpi_unbind(struct ata_device *dev) { }
> +static inline void ata_acpi_hotplug_init(struct ata_host *host) {}
>  #endif
>  
>  /* libata-scsi.c */
>