scsi: ips: Replace kmap_atomic() with kmap_local_page()

kmap_atomic() is deprecated in favor of kmap_local_page(). Therefore,
replace kmap_atomic() with kmap_local_page() in ips_is_passthru(). In the
meantime remove an unnecessary comment, align code, and remove spaces.

kmap_atomic() is implemented like a kmap_local_page() which also disables
page-faults and preemption (the latter only for !PREEMPT_RT kernels).  The
code within the mapping/unmapping in ips_is_passthru() is already in atomic
context because of a call to local_irq_save() and kmap_local_page() can be
called in atomic context too (including interrupts).

Therefore, a mere replacement of the old API with the new one is all it is
required (i.e., there is no need to explicitly add any calls to
pagefault_disable() and/or preempt_disable()).
Suggested-by: NIra Weiny <ira.weiny@intel.com>
Signed-off-by: NFabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: NIra Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20230103173131.21259-1-fmdefrancesco@gmail.comSigned-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ips.c

@@ -1499,17 +1499,16 @@ static int ips_is_passthru(struct scsi_cmnd *SC)
                 struct scatterlist *sg = scsi_sglist(SC);
                 char  *buffer;
 
-                /* kmap_atomic() ensures addressability of the user buffer.*/
                 /* local_irq_save() protects the KM_IRQ0 address slot.     */
                 local_irq_save(flags);
-                buffer = kmap_atomic(sg_page(sg)) + sg->offset;
-                if (buffer && buffer[0] == 'C' && buffer[1] == 'O' &&
-                    buffer[2] == 'P' && buffer[3] == 'P') {
-                        kunmap_atomic(buffer - sg->offset);
+		buffer = kmap_local_page(sg_page(sg)) + sg->offset;
+		if (buffer && buffer[0] == 'C' && buffer[1] == 'O' &&
+		    buffer[2] == 'P' && buffer[3] == 'P') {
+			kunmap_local(buffer);
                         local_irq_restore(flags);
                         return 1;
                 }
-                kunmap_atomic(buffer - sg->offset);
+		kunmap_local(buffer);
                 local_irq_restore(flags);
 	}
 	return 0;