ide: take ide_lock for prefetch disable/enable in do_special()

Index: b/drivers/ide/ide-io.c
===================================================================
@@ -835,7 +835,20 @@ static ide_startstop_t do_special (ide_d
 		s->b.set_tune = 0;
 
 		if (set_pio_mode_abuse(drive->hwif, req_pio)) {
-			if (hwif->set_pio_mode)
+
+			if (hwif->set_pio_mode == NULL)
+				return ide_stopped;
+
+			/*
+			 * take ide_lock for drive->[no_]unmask/[no_]io_32bit
+			 */
+			if (req_pio == 8 || req_pio == 9) {
+				unsigned long flags;
+
+				spin_lock_irqsave(&ide_lock, flags);
+				hwif->set_pio_mode(drive, req_pio);
+				spin_unlock_irqrestore(&ide_lock, flags);
+			} else
 				hwif->set_pio_mode(drive, req_pio);
 		} else {
 			int keep_dma = drive->using_dma;

Index: b/drivers/ide/legacy/ht6560b.c
===================================================================
@@ -286,12 +286,7 @@ static void ht6560b_set_pio_mode(ide_dri
 	switch (pio) {
 	case 8:         /* set prefetch off */
 	case 9:         /* set prefetch on */
-		/*
-		 * take ide_lock for drive->[no_]unmask
-		 */
-		spin_lock_irqsave(&ide_lock, flags);
 		ht_set_prefetch(drive, pio & 1);
-		spin_unlock_irqrestore(&ide_lock, flags);
 		return;
 	}
 

Index: b/drivers/ide/pci/cmd640.c
===================================================================
@@ -632,7 +632,6 @@ static void cmd640_set_mode (unsigned in
 
 static void cmd640_set_pio_mode(ide_drive_t *drive, const u8 pio)
 {
-	unsigned long flags;
 	unsigned int index = 0, cycle_time;
 	u8 b;
 

@@ -655,12 +654,7 @@ static void cmd640_set_pio_mode(ide_driv
 
 		case 8: /* set prefetch off */
 		case 9: /* set prefetch on */
-			/*
-			 * take ide_lock for drive->[no_]unmask/[no_]io_32bit
-			 */
-			spin_lock_irqsave(&ide_lock, flags);
 			set_prefetch_mode(index, pio & 1);
-			spin_unlock_irqrestore(&ide_lock, flags);
 			printk("%s: %sabled cmd640 prefetch\n", drive->name, (pio & 1) ? "en" : "dis");
 			return;
 	}