[bug report] scsi: elx: efct: LIO backend interface routines

[bug report] scsi: elx: efct: LIO backend interface routines

[Dan Carpenter]

Hello James Smart,

The patch 692e5d73a811: "scsi: elx: efct: LIO backend interface
routines" from Jun 1, 2021, leads to the following
Smatch static checker warning:

	drivers/base/power/sysfs.c:833 dpm_sysfs_remove()
	warn: sleeping in atomic context

drivers/base/power/sysfs.c
    829 void dpm_sysfs_remove(struct device *dev)
    830 {
    831         if (device_pm_not_required(dev))
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^
If this is true then the warning is a false positive.

    832                 return;
--> 833         sysfs_unmerge_group(&dev->kobj, &pm_qos_latency_tolerance_attr_group);

It's the down_read() in kernfs_find_and_get_ns() that sleeps.

    834         dev_pm_qos_constraints_destroy(dev);
    835         rpm_sysfs_remove(dev);
    836         sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
    837         sysfs_remove_group(&dev->kobj, &pm_attr_group);
    838 }

The call tree is:

efct_lio_npiv_drop_nport() <- disables preempt
-> fc_vport_terminate()
   -> device_del()
      -> dpm_sysfs_remove()

drivers/scsi/elx/efct/efct_lio.c
   875  efct_lio_npiv_drop_nport(struct se_wwn *wwn)
   876  {
   877          struct efct_lio_vport *lio_vport =
   878                  container_of(wwn, struct efct_lio_vport, vport_wwn);
   879          struct efct_lio_vport_list_t *vport, *next_vport;
   880          struct efct *efct = lio_vport->efct;
   881          unsigned long flags = 0;
   882  
   883          spin_lock_irqsave(&efct->tgt_efct.efct_lio_lock, flags);
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Holding a lock.

   884  
   885          if (lio_vport->fc_vport)
   886                  fc_vport_terminate(lio_vport->fc_vport);
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Sleeps on the success path unless device_pm_not_required() is true in
dpm_sysfs_remove().

   887  
   888          list_for_each_entry_safe(vport, next_vport, &efct->tgt_efct.vport_list,
   889                                   list_entry) {
   890                  if (vport->lio_vport == lio_vport) {
   891                          list_del(&vport->list_entry);
   892                          kfree(vport->lio_vport);
   893                          kfree(vport);
   894                          break;
   895                  }
   896          }
   897          spin_unlock_irqrestore(&efct->tgt_efct.efct_lio_lock, flags);
   898  }

regards,
dan carpenter