ACK: [PATCH 1/1] libata: Use per port sync for detach

[Kamal Mostafa]

LGTM.

Acked-by: Kamal Mostafa <kamal at canonical.com>

 -Kamal

On Thu, Jul 09, 2020 at 09:00:43PM +0800, Kai-Heng Feng wrote:
> Commit 130f4caf145c ("libata: Ensure ata_port probe has completed before
> detach") may cause system freeze during suspend.
> 
> Using async_synchronize_full() in PM callbacks is wrong, since async
> callbacks that are already scheduled may wait for not-yet-scheduled
> callbacks, causes a circular dependency.
> 
> Instead of using big hammer like async_synchronize_full(), use async
> cookie to make sure port probe are synced, without affecting other
> scheduled PM callbacks.
> 
> Fixes: 130f4caf145c ("libata: Ensure ata_port probe has completed before detach")
> Suggested-by: John Garry <john.garry at huawei.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
> Tested-by: John Garry <john.garry at huawei.com>
> BugLink: https://bugs.launchpad.net/bugs/1867983
> Signed-off-by: Jens Axboe <axboe at kernel.dk>
> (cherry picked from commit b5292111de9bb70cba3489075970889765302136)
> Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
> ---
>  drivers/ata/libata-core.c | 11 +++++------
>  include/linux/libata.h    |  3 +++
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 581595b35573..35f75c691d7c 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -41,7 +41,6 @@
>  #include <linux/workqueue.h>
>  #include <linux/scatterlist.h>
>  #include <linux/io.h>
> -#include <linux/async.h>
>  #include <linux/log2.h>
>  #include <linux/slab.h>
>  #include <linux/glob.h>
> @@ -6592,7 +6591,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
>  	/* perform each probe asynchronously */
>  	for (i = 0; i < host->n_ports; i++) {
>  		struct ata_port *ap = host->ports[i];
> -		async_schedule(async_port_probe, ap);
> +		ap->cookie = async_schedule(async_port_probe, ap);
>  	}
>  
>  	return 0;
> @@ -6732,11 +6731,11 @@ void ata_host_detach(struct ata_host *host)
>  {
>  	int i;
>  
> -	/* Ensure ata_port probe has completed */
> -	async_synchronize_full();
> -
> -	for (i = 0; i < host->n_ports; i++)
> +	for (i = 0; i < host->n_ports; i++) {
> +		/* Ensure ata_port probe has completed */
> +		async_synchronize_cookie(host->ports[i]->cookie + 1);
>  		ata_port_detach(host->ports[i]);
> +	}
>  
>  	/* the host is dead now, dissociate ACPI */
>  	ata_acpi_dissociate(host);
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index c44e4cfbcb16..b9970f5bab67 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -22,6 +22,7 @@
>  #include <linux/acpi.h>
>  #include <linux/cdrom.h>
>  #include <linux/sched.h>
> +#include <linux/async.h>
>  
>  /*
>   * Define if arch has non-standard setup.  This is a _PCI_ standard
> @@ -870,6 +871,8 @@ struct ata_port {
>  	struct timer_list	fastdrain_timer;
>  	unsigned long		fastdrain_cnt;
>  
> +	async_cookie_t		cookie;
> +
>  	int			em_message_type;
>  	void			*private_data;
>  
> -- 
> 2.17.1
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team