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

Avri Altman
2019-12-11T13:44:46Z

> 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@codeaurora.org>
> >> >
> >> > 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".
OK.