scsi: target: iblock: Fix smp_processor_id() BUG messages

This has us use raw_smp_processor_id() in iblock's plug_device callout.
smp_processor_id() is not needed here, because we are running from a per
CPU work item that is also queued to run on a worker thread that is
normally bound to a specific CPU. If the worker thread did end up switching
CPUs then it's handled the same way we handle when the work got moved to a
different CPU's worker thread, where we will just end up sending I/O from
the new CPU.

Link: https://lore.kernel.org/r/20210519222640.5153-1-michael.christie@oracle.com
Fixes: 415ccd98 ("scsi: target: iblock: Add backend plug/unplug callouts")
Signed-off-by: NMike Christie <michael.christie@oracle.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/target/target_core_iblock.c

@@ -204,11 +204,11 @@ static struct se_dev_plug *iblock_plug_device(struct se_device *se_dev)
 	struct iblock_dev_plug *ib_dev_plug;
 
 	/*
-	 * Each se_device has a per cpu work this can be run from. Wwe
+	 * Each se_device has a per cpu work this can be run from. We
 	 * shouldn't have multiple threads on the same cpu calling this
 	 * at the same time.
 	 */
-	ib_dev_plug = &ib_dev->ibd_plug[smp_processor_id()];
+	ib_dev_plug = &ib_dev->ibd_plug[raw_smp_processor_id()];
 	if (test_and_set_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags))
 		return NULL;