Re: [PATCH 1/1] s390/dasd: Fix inconsistent kobject removal

[Stefan Haberland <sth@linux.ibm.com>]

Hi Jens,

small question.
Do you plan to include the fix still for 5.11 or with the merge window
for 5.12?
The faulty patch was included in the 5.11 merge window.

Best regards,
Stefan

Am 18.01.21 um 17:55 schrieb Stefan Haberland:
> From: Jan Höppner <hoeppner@linux.ibm.com>
>
> Our intention was to only remove path kobjects whenever a device is
> being set offline. However, one corner case was missing.
>
> If a device is disabled and enabled (using the IOCTLs BIODASDDISABLE and
> BIODASDENABLE respectively), the enabling process will call
> dasd_eckd_reload_device() which itself calls dasd_eckd_read_conf() in
> order to update path information. During that update,
> dasd_eckd_clear_conf_data() clears all old data and also removes all
> kobjects. This will leave us with an inconsistent state of path kobjects
> and a subsequent path verification leads to a failing kobject creation.
>
> Fix this by removing kobjects only in the context of offlining a device
> as initially intended.
>
> Fixes: 19508b204740 ("s390/dasd: Display FC Endpoint Security information via sysfs")
> Reported-by: Stefan Haberland <sth@linux.ibm.com>
> Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
> Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
> ---
>  drivers/s390/block/dasd_devmap.c | 20 ++++++++++++++------
>  drivers/s390/block/dasd_eckd.c   |  3 ++-
>  drivers/s390/block/dasd_int.h    |  2 +-
>  3 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
> index 16bb135c20aa..03d27ee9cac6 100644
> --- a/drivers/s390/block/dasd_devmap.c
> +++ b/drivers/s390/block/dasd_devmap.c
> @@ -1874,18 +1874,26 @@ void dasd_path_create_kobjects(struct dasd_device *device)
>  }
>  EXPORT_SYMBOL(dasd_path_create_kobjects);
>  
> -/*
> - * As we keep kobjects for the lifetime of a device, this function must not be
> - * called anywhere but in the context of offlining a device.
> - */
> -void dasd_path_remove_kobj(struct dasd_device *device, int chp)
> +static void dasd_path_remove_kobj(struct dasd_device *device, int chp)
>  {
>  	if (device->path[chp].in_sysfs) {
>  		kobject_put(&device->path[chp].kobj);
>  		device->path[chp].in_sysfs = false;
>  	}
>  }
> -EXPORT_SYMBOL(dasd_path_remove_kobj);
> +
> +/*
> + * As we keep kobjects for the lifetime of a device, this function must not be
> + * called anywhere but in the context of offlining a device.
> + */
> +void dasd_path_remove_kobjects(struct dasd_device *device)
> +{
> +	int i;
> +
> +	for (i = 0; i < 8; i++)
> +		dasd_path_remove_kobj(device, i);
> +}
> +EXPORT_SYMBOL(dasd_path_remove_kobjects);
>  
>  int dasd_add_sysfs_files(struct ccw_device *cdev)
>  {
> diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
> index 3caa1ee5f4b0..65eb87cbbb9b 100644
> --- a/drivers/s390/block/dasd_eckd.c
> +++ b/drivers/s390/block/dasd_eckd.c
> @@ -1036,7 +1036,6 @@ static void dasd_eckd_clear_conf_data(struct dasd_device *device)
>  		device->path[i].ssid = 0;
>  		device->path[i].chpid = 0;
>  		dasd_path_notoper(device, i);
> -		dasd_path_remove_kobj(device, i);
>  	}
>  }
>  
> @@ -2173,6 +2172,7 @@ dasd_eckd_check_characteristics(struct dasd_device *device)
>  	device->block = NULL;
>  out_err1:
>  	dasd_eckd_clear_conf_data(device);
> +	dasd_path_remove_kobjects(device);
>  	kfree(device->private);
>  	device->private = NULL;
>  	return rc;
> @@ -2191,6 +2191,7 @@ static void dasd_eckd_uncheck_device(struct dasd_device *device)
>  	private->vdsneq = NULL;
>  	private->gneq = NULL;
>  	dasd_eckd_clear_conf_data(device);
> +	dasd_path_remove_kobjects(device);
>  }
>  
>  static struct dasd_ccw_req *
> diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
> index 3bc008f9136c..b8a04c42d1d2 100644
> --- a/drivers/s390/block/dasd_int.h
> +++ b/drivers/s390/block/dasd_int.h
> @@ -858,7 +858,7 @@ int dasd_add_sysfs_files(struct ccw_device *);
>  void dasd_remove_sysfs_files(struct ccw_device *);
>  void dasd_path_create_kobj(struct dasd_device *, int);
>  void dasd_path_create_kobjects(struct dasd_device *);
> -void dasd_path_remove_kobj(struct dasd_device *, int);
> +void dasd_path_remove_kobjects(struct dasd_device *);
>  
>  struct dasd_device *dasd_device_from_cdev(struct ccw_device *);
>  struct dasd_device *dasd_device_from_cdev_locked(struct ccw_device *);