Re: [PATCH] scsi: core: Allow the state change from SDEV_QUIESCE to SDEV_BLOCK

[Ming Lei]

On Tue, Apr 21, 2020 at 03:01:34AM +0000, Dexuan Cui wrote:
> > From: Ming Lei <ming.lei@xxxxxxxxxx>
> > Sent: Friday, April 17, 2020 7:42 PM
> > To: Dexuan Cui <decui@xxxxxxxxxxxxx>
> > Cc: jejb@xxxxxxxxxxxxx; martin.petersen@xxxxxxxxxx;
> > linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; hch@xxxxxx;
> > bvanassche@xxxxxxx; hare@xxxxxxx; Michael Kelley
> > <mikelley@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx>
> > Subject: Re: [PATCH] scsi: core: Allow the state change from SDEV_QUIESCE to
> > SDEV_BLOCK
> > 
> > On Fri, Apr 17, 2020 at 05:40:45PM -0700, Dexuan Cui wrote:
> > > The APIs scsi_host_block()/scsi_host_unblock() are recently added by:
> > > 2bb955840c1d ("scsi: core: add scsi_host_(block,unblock) helper function")
> > > and so far the APIs are only used by:
> > > 3d3ca53b1639 ("scsi: aacraid: use scsi_host_(block,unblock) to block I/O")
> > >
> > > However, from reading the code, I think the APIs don't really work for
> > > aacraid, because, in the resume path of hibernation, when aac_suspend() ->
> > > scsi_host_block() is called, scsi_device_quiesce() has set the state to
> > > SDEV_QUIESCE, so aac_suspend() -> scsi_host_block() returns -EINVAL.
> > >
> > > Fix the issue by allowing the state change.
> > >
> > > Fixes: 2bb955840c1d ("scsi: core: add scsi_host_(block,unblock) helper
> > function")
> > > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> > > ---
> > >  drivers/scsi/scsi_lib.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > > index 47835c4b4ee0..06c260f6cdae 100644
> > > --- a/drivers/scsi/scsi_lib.c
> > > +++ b/drivers/scsi/scsi_lib.c
> > > @@ -2284,6 +2284,7 @@ scsi_device_set_state(struct scsi_device *sdev,
> > enum scsi_device_state state)
> > >  		switch (oldstate) {
> > >  		case SDEV_RUNNING:
> > >  		case SDEV_CREATED_BLOCK:
> > > +		case SDEV_QUIESCE:
> > >  		case SDEV_OFFLINE:
> > >  			break;
> > >  		default:
> > 
> > Looks reasonable because SDEV_BLOCK is one more strict state than
> > QEIESCE, so:
> 
> Thanks, Ming!
> 
> > Reviewed-by: Ming Lei <ming.lei@xxxxxxxxx>
> > 
> > Thanks,
> > Ming
> 
> There should be a small typo: s/redha/redhat :-)

Sorry for the fault:

Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>

Thanks,
Ming