Re: [PATCH V3 3/3] scsi: core: put ->shost_gendev.parent in failure handling path

[Ming Lei <ming.lei@redhat.com>]

On Mon, May 31, 2021 at 10:23:43AM +0200, Hannes Reinecke wrote:
> On 5/31/21 9:56 AM, Ming Lei wrote:
> > On Mon, May 31, 2021 at 08:28:49AM +0200, Hannes Reinecke wrote:
> > > On 5/31/21 7:07 AM, Ming Lei wrote:
> > > > get_device(shost->shost_gendev.parent) is called in
> > > > scsi_add_host_with_dma(), but its counter pair isn't called in the failure
> > > > path, so fix it by calling put_device(shost->shost_gendev.parent) in its
> > > > failure path.
> > > > 
> > > > Reported-by: John Garry <john.garry@huawei.com>
> > > > Cc: Bart Van Assche <bvanassche@acm.org>
> > > > Cc: Hannes Reinecke <hare@suse.de>
> > > > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > > > ---
> > > >    drivers/scsi/hosts.c | 1 +
> > > >    1 file changed, 1 insertion(+)
> > > > 
> > > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> > > > index 6cbc3eb16525..6cc43c51b7b3 100644
> > > > --- a/drivers/scsi/hosts.c
> > > > +++ b/drivers/scsi/hosts.c
> > > > @@ -298,6 +298,7 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
> > > >     out_del_dev:
> > > >    	device_del(&shost->shost_dev);
> > > >     out_del_gendev:
> > > > +	put_device(shost->shost_gendev.parent);
> > > >    	device_del(&shost->shost_gendev);
> > > >     out_disable_runtime_pm:
> > > >    	device_disable_async_suspend(&shost->shost_gendev);
> > > > 
> > > This really needs to be folded into the first patch as it's really a bugfix
> > > for that.
> > 
> > All three are bug fixes, and this one may leak .shost_gendev's parent,
> > but the 1st one leaks .shost_gendev->kobj.name, so we needn't to fold
> > the 3rd into the 1st one.
> > 
> I beg to disagree.
> The first patch removes the 'get_device()' from
> scsi_add_host_with_dma(), but does not remove the corresponding
> 'put_device()' in the error path.

There isn't such 'put_device' in the error path of scsi_add_host_with_dma(),
is there?

> So the first patch introduces a reference imbalance which is fixed by the
> third patch. Hence my suggestion to merge those two patches.

No, that isn't true, please look at current code of
scsi_add_host_with_dma().


Thanks, 
Ming