Re: [PATCH 1/2] scsi: ufs: Put SCSI host after remove it

cang
2019-12-14T22:24:50Z

On 2019-12-15 02:32, Bart Van Assche wrote:
> On 12/14/19 8:03 AM, Can Guo 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>
>>
>> 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);
>
> Hi Can,
>
> The UFS driver may queue work asynchronously and that asynchronous
> work may refer to the SCSI host, e.g. ufshcd_err_handler(). Is it
> guaranteed that all that asynchronous work has finished before
> scsi_host_put() is called?
>
> Thanks,
>
> Bart.

Hi Bart,

Thanks for pointing it out. I noticed that you are changing this
path too in below 2 changes.
https://marc.info/?l=linux-scsi&m=157591520015924&w=2
https://marc.info/?l=linux-scsi&m=157591519915923&w=2

Actually the async works you pointed may also affect your change,
because you may tear down the hba->cmd_queue too early, as there can be
devm commands sent by clock gating, eeh_work and eh_work after that
point,
meaning when blk_get_request is called in exec_dev_cmd(), hba->cmd_queue
may have been released already.

@@ -8263,6 +8232,7 @@ void ufshcd_remove(struct ufs_hba *hba)
{
ufs_bsg_remove(hba);
ufs_sysfs_remove_nodes(hba->dev);
+ blk_cleanup_queue(hba->cmd_queue);
scsi_remove_host(hba->host);
/* disable interrupts */
ufshcd_disable_intr(hba, hba->intr_mask);

How do you think if I replace my patch with below one?
In this way, you can also move blk_cleanup_queue() behind
cancel_work_sync(eh_work).

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index b5966fa..bd4ae75 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -8251,15 +8251,17 @@ void ufshcd_remove(struct ufs_hba *hba)
ufs_bsg_remove(hba);
ufs_sysfs_remove_nodes(hba->dev);
scsi_remove_host(hba->host);
- /* disable interrupts */
- ufshcd_disable_intr(hba, hba->intr_mask);
- ufshcd_hba_stop(hba, true);
-
ufshcd_exit_clk_scaling(hba);
ufshcd_exit_clk_gating(hba);
if (ufshcd_is_clkscaling_supported(hba))
device_remove_file(hba->dev,
&hba->clk_scaling.enable_attr);
+ cancel_work_sync(&hba->eeh_work);
+ cancel_work_sync(&hba->eh_work);
+ /* disable interrupts */
+ ufshcd_disable_intr(hba, hba->intr_mask);
+ ufshcd_hba_stop(hba, true);
ufshcd_hba_exit(hba);
+ ufshcd_dealloc_host(hba);
}
EXPORT_SYMBOL_GPL(ufshcd_remove);

--

Thanks,

Can Guo.