[dm-devel] md/dm-table: tgt->type should be putted in dm_table_add_target()

[tang.junhui at zte.com.cn]

Hello, Mike

Thanks for your quick respond. 
This problem causes failure in "rmmod dm-spp" command,
(dm-spp is a tagert type for our product)
since the reference count is not zero due to 
the failure of DM table loads.

I don't intend to cc stable, I just add the 
"Cc: stable at vger.kernel.org" after Signed-off-by in
commit message as Bart suggested it to me, then I send email
by "git send-email" command, and it cc to stable automatically,
I think maybe my git is not configured well, I'll research it 
later.

(BTW, I like your name, Mike, Thank you for your accompanying 
with us in our English class for so many years.) 

thanks,

Tang
 



发件人:         Mike Snitzer <snitzer at redhat.com>
收件人:         tang.junhui at zte.com.cn, 
抄送:   zhang.kai16 at zte.com.cn, dm-devel at redhat.com, 
stable at vger.kernel.org, agk at redhat.com
日期:   2016/10/21 10:24
主题:   Re: [dm-devel] md/dm-table: tgt->type should be putted in 
dm_table_add_target()
发件人: dm-devel-bounces at redhat.com



On Thu, Oct 20 2016 at  9:35pm -0400,
tang.junhui at zte.com.cn <tang.junhui at zte.com.cn> wrote:

> From: "tang.junhui" <tang.junhui at zte.com.cn>
> 
> tgt->type should be putted in dm_table_add_target()
> when the target do not statisfy the needs of target type,
> otherwise it would cause the module reference count
> of this target type leakage.
> 
> Signed-off-by: tang.junhui <tang.junhui at zte.com.cn>
> Cc: stable at vger.kernel.org

This issue, missing dm_put_target_type, dates back to 2011.

See these 3 commits:
$ git log --oneline 3791e2fc0^..36a0456fb
36a0456 dm table: add immutable feature
cc6cbe1 dm table: add always writeable feature
3791e2f dm table: add singleton feature

So are you having problems with failed DM table loads (due to the errors
below) resulting in the inability to unload a DM module?

(BTW, you don't need to cc stable when initially proposing a patch for
stable.  The stable@ maintainers will automatically pull such stable@
changes in once they land in Linus' tree.)

Mike

> ---
>  drivers/md/dm-table.c | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 6554d91..4f56c38 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -698,30 +698,30 @@ int dm_table_add_target(struct dm_table *t, const 
char *type,
> 
>                if (dm_target_needs_singleton(tgt->type)) {
>                                if (t->num_targets) {
> -                                              DMERR("%s: target type %s 
must appear alone in table",
> - dm_device_name(t->md), type);
> -                                              return -EINVAL;
> +                                              tgt->error = "target type 
must appear alone in table";
> +                                              r = -EINVAL;
> +                                              goto bad;
>                                }
>                                t->singleton = 1;
>                }
> 
>                if (dm_target_always_writeable(tgt->type) && !(t->mode & 
FMODE_WRITE)) {
> -                              DMERR("%s: target type %s may not be 
included in read-only tables",
> -                                    dm_device_name(t->md), type);
> -                              return -EINVAL;
> +                              tgt->error = "target type may not be 
included in read-only tables";
> +                              r = -EINVAL;
> +                              goto bad;
>                }
> 
>                if (t->immutable_target_type) {
>                                if (t->immutable_target_type != 
tgt->type) {
> -                                              DMERR("%s: immutable 
target type %s cannot be mixed with other target types",
> - dm_device_name(t->md), t->immutable_target_type->name);
> -                                              return -EINVAL;
> +                                              tgt->error = "immutable 
target type cannot be mixed with other target types";
> +                                              r = -EINVAL;
> +                                              goto bad;
>                                }
>                } else if (dm_target_is_immutable(tgt->type)) {
>                                if (t->num_targets) {
> -                                              DMERR("%s: immutable 
target type %s cannot be mixed with other target types",
> - dm_device_name(t->md), tgt->type->name);
> -                                              return -EINVAL;
> +                                              tgt->error = "immutable 
target type cannot be mixed with other target types";
> +                                              r = -EINVAL;
> +                                              goto bad;
>                                }
>                                t->immutable_target_type = tgt->type;
>                }
> -- 
> 2.8.1.windows.1
> 

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