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

[cang]

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@xxxxxxxxxxxxxx>
> >
> > 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.