On Thu, Sep 30, 2021 at 08:44:15PM +0800, Ming Lei wrote:
> SCSI host release is triggered when SCSI device is freed, and we have to
> make sure that LLD module won't be unloaded before SCSI host instance is
> released because shost->hostt is required in host release handler.
>
> So make sure to put LLD module refcnt after SCSI device is released.
What is a "LLD"?
> Fix one kernel panic of 'BUG: unable to handle page fault for address'
> reported by Changhui and Yi.
>
> Reported-by: Changhui Zhong <czhong@xxxxxxxxxx>
> Reported-by: Yi Zhang <yi.zhang@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> drivers/scsi/scsi.c | 4 +++-
> drivers/scsi/scsi_sysfs.c | 12 ++++++++++++
> include/scsi/scsi_device.h | 1 +
> 3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index b241f9e3885c..291ecc33b1fe 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -553,8 +553,10 @@ EXPORT_SYMBOL(scsi_device_get);
> */
> void scsi_device_put(struct scsi_device *sdev)
> {
> - module_put(sdev->host->hostt->module);
> + struct module *mod = sdev->host->hostt->module;
> +
> put_device(&sdev->sdev_gendev);
> + module_put(mod);
> }
> EXPORT_SYMBOL(scsi_device_put);
>
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 86793259e541..9ada26814011 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -449,9 +449,16 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
> struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL;
> struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL;
> unsigned long flags;
> + struct module *mod;
> + bool put_mod = false;
>
> sdev = container_of(work, struct scsi_device, ew.work);
>
> + if (sdev->put_lld_mod_ref) {
Why do you need this flag at all?
Shouldn't you just always grab/release the module? Why would you not
want to?
thanks,
greg k-h
