[Crash-utility] [PATCH] Fix for the "dev -[dD]" options on Linux 5.1-rc1 and later

[Dave Anderson]

----- Original Message -----
> Fix for the "dev -[dD]" options on Linux 5.1-rc1 and later kernels
> that contain commit 570d0200123fb4f809aa2f6226e93a458d664d70,
> titled "driver core: move device->knode_class to device_private".
> Without the patch, the commands fail with the following error message:
> 
>   dev: invalid structure member offset: device_knode_class
>        FILE: dev.c  LINE: 4046  FUNCTION: match_klist()
> 
> Signed-off-by: Kazuhito Hagio <k-hagio at ab.jp.nec.com>

Thanks Kazu, the patch is queued for crash-7.2.6:

  https://github.com/crash-utility/crash/commit/dc70e6a5e0f6f9823070d647b545a8a9282c388e

Dave


> ---
>  defs.h    |  1 +
>  dev.c     | 34 ++++++++++++++++++++++++++++++++--
>  symbols.c |  2 ++
>  3 files changed, 35 insertions(+), 2 deletions(-)
> 
> diff --git a/defs.h b/defs.h
> index 2466681..db192f3 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2068,6 +2068,7 @@ struct offset_table {                    /* stash of
> commonly-used offsets */
>  	long disk_stats_in_flight;
>  	long cpu_context_save_r7;
>  	long dentry_d_sb;
> +	long device_private_knode_class;
>  };
>  
>  struct size_table {         /* stash of commonly-used sizes */
> diff --git a/dev.c b/dev.c
> index 24efea2..91b81f3 100644
> --- a/dev.c
> +++ b/dev.c
> @@ -4020,6 +4020,21 @@ get_gendisk_4(unsigned long entry)
>  		OFFSET(gendisk_part0);
>  }
>  
> +/* kernel version >= 5.1 */
> +static unsigned long
> +get_gendisk_5(unsigned long entry)
> +{
> +	unsigned long device_address;
> +	unsigned long device_private_address;
> +
> +	device_private_address = entry - OFFSET(device_private_knode_class);
> +	readmem(device_private_address + OFFSET(device_private_device),
> +		KVADDR, &device_address, sizeof(device_address),
> +		"device_private.device", FAULT_ON_ERROR);
> +
> +	return device_address - OFFSET(hd_struct_dev) - OFFSET(gendisk_part0);
> +}
> +
>  /* 2.6.24 < kernel version <= 2.6.27 */
>  static int
>  match_list(struct iter *i, unsigned long entry)
> @@ -4042,8 +4057,18 @@ match_klist(struct iter *i, unsigned long entry)
>  {
>  	unsigned long device_address;
>  	unsigned long device_type;
> +	unsigned long device_private_address;
>  
> -	device_address = entry - OFFSET(device_knode_class);
> +	if (VALID_MEMBER(device_knode_class))
> +		device_address = entry - OFFSET(device_knode_class);
> +	else {
> +		/* kernel version >= 5.1 */
> +		device_private_address = entry -
> +			OFFSET(device_private_knode_class);
> +		readmem(device_private_address + OFFSET(device_private_device),
> +			KVADDR, &device_address, sizeof(device_address),
> +			"device_private.device", FAULT_ON_ERROR);
> +	}
>  	readmem(device_address + OFFSET(device_type), KVADDR, &device_type,
>  		sizeof(device_type), "device.type", FAULT_ON_ERROR);
>  	if (device_type != i->type_address)
> @@ -4348,8 +4373,10 @@ init_iter(struct iter *i)
>  			i->match = match_klist;
>  			if (VALID_MEMBER(gendisk_dev))
>  				i->get_gendisk = get_gendisk_3;
> -			else
> +			else if (VALID_MEMBER(device_knode_class))
>  				i->get_gendisk = get_gendisk_4;
> +			else
> +				i->get_gendisk = get_gendisk_5;
>  		}
>  	} else {
>  		option_not_supported('d');
> @@ -4470,6 +4497,9 @@ void diskio_init(void)
>  	MEMBER_OFFSET_INIT(device_knode_class, "device", "knode_class");
>  	MEMBER_OFFSET_INIT(device_node, "device", "node");
>  	MEMBER_OFFSET_INIT(device_type, "device", "type");
> +	MEMBER_OFFSET_INIT(device_private_device, "device_private", "device");
> +	MEMBER_OFFSET_INIT(device_private_knode_class, "device_private",
> +		"knode_class");
>  	MEMBER_OFFSET_INIT(gendisk_dev, "gendisk", "dev");
>  	if (INVALID_MEMBER(gendisk_dev))
>  		MEMBER_OFFSET_INIT(gendisk_dev, "gendisk", "__dev");
> diff --git a/symbols.c b/symbols.c
> index 1ed75fe..da68eda 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -10113,6 +10113,8 @@ dump_offset_table(char *spec, ulong makestruct)
>  		OFFSET(device_private_device));
>  	fprintf(fp, "      device_private_knode_bus: %ld\n",
>  		OFFSET(device_private_knode_bus));
> +	fprintf(fp, "    device_private_knode_class: %ld\n",
> +		OFFSET(device_private_knode_class));
>  	fprintf(fp, "                   gendisk_dev: %ld\n",
>  		OFFSET(gendisk_dev));
>  	fprintf(fp, "                  gendisk_kobj: %ld\n",
> --
> 2.18.1
> 
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