Re: [PATCH v2 1/3] scsi: ufs: Put SCSI host after remove it

[cang]

On 2019-12-11 19:22, Avri Altman wrote:
> > On 2019-12-11 18:37, Avri Altman wrote:
> > >>
> > >> In ufshcd_remove(), after SCSI host is removed, put it once so that
> > >> its resources can be released.
> > >>
> > >> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> > >
> > > This is not really part of this patchset, is it?
> > >
> >
> > Hi Avri,
> >
> > I put this change in the same patchset due to #1. The main patch has
> > dependency on it #2. Consider a scenario where platform driver is also 
> > compiled
> > as a module, say ufs_qcom.ko.
> >      In this case, we have two modules, ufs-qcom.ko and ufs-bsg.ko. If 
> > do insmod
> > ufs-qcom.ko
> >      then rmmod ufs-qcom.ko and do insmod ufs-qcom.ko again, without 
> > this
> > change, because scsi
> >      host was not release, the new scsi host will have a different 
> > host number,
> > meaning
> >      hba->host->host_no will be 1, but not 0. Now if do insmod 
> > ufs-bsg.ko now,
> > the ufs-bsg dev
> >      created in /dev/bsg/ will be ufs-bsg1, but not ufs-bsg0. If keep 
> > trying these
> > operations,
> >      the ufs-bsg device's name will be messed up. This change make 
> > sure after ufs-
> > qcom.ko is removed
> >      and installed back, its hba->host->host_no stays 0, so that 
> > ufs-bsg device
> > name stays same.
> Looks like we needed to manage the ufs-bsg nodes using an IDA, instead
> of host_no?

Marking one ufs-bsg dev with host_no still has its advantage. If we have 
more
than one hba host, we can find the right ufs-bsgX dev by reading the 
sg/sd/bsg
device's host->host_unique_id (through SCSI_IOCTL_GET_IDLUN for 
example).
But If ufs-bsg has its own ID, we will lost this "mapping".

Thanks,

Can Guo.

> > Thanks,
> >
> > Can Guo.
> >
> > >> ---
> > >>  drivers/scsi/ufs/ufshcd.c | 1 +
> > >>  1 file changed, 1 insertion(+)
> > >>
> > >> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > >> index b5966fa..a86b0fd 100644
> > >> --- a/drivers/scsi/ufs/ufshcd.c
> > >> +++ b/drivers/scsi/ufs/ufshcd.c
> > >> @@ -8251,6 +8251,7 @@ void ufshcd_remove(struct ufs_hba *hba)
> > >>         ufs_bsg_remove(hba);
> > >>         ufs_sysfs_remove_nodes(hba->dev);
> > >>         scsi_remove_host(hba->host);
> > >> +       scsi_host_put(hba->host);
> > >>         /* disable interrupts */
> > >>         ufshcd_disable_intr(hba, hba->intr_mask);
> > >>         ufshcd_hba_stop(hba, true);
> > >> --
> > >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> > >> Forum, a Linux Foundation Collaborative Project