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

cang
2019-12-11T11:44:11Z

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".

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