firewire: ohci: use guard macro to maintain image of configuration ROM

The 1394 OHCI driver uses spinlock for the process to update local
configuration ROM.

This commit uses guard macro to maintain the spinlock.

Link: https://lore.kernel.org/r/20240805085408.251763-17-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

Author: takaswie

drivers/firewire/ohci.c

@@ -2139,53 +2139,42 @@ static void bus_reset_work(struct work_struct *work)
 	at_context_flush(&ohci->at_request_ctx);
 	at_context_flush(&ohci->at_response_ctx);
 
-	spin_lock_irq(&ohci->lock);
-
-	ohci->generation = generation;
-	reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);
-	reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_busReset);
-
-	if (ohci->quirks & QUIRK_RESET_PACKET)
-		ohci->request_generation = generation;
-
-	/*
-	 * This next bit is unrelated to the AT context stuff but we
-	 * have to do it under the spinlock also.  If a new config rom
-	 * was set up before this reset, the old one is now no longer
-	 * in use and we can free it. Update the config rom pointers
-	 * to point to the current config rom and clear the
-	 * next_config_rom pointer so a new update can take place.
-	 */
-
-	if (ohci->next_config_rom != NULL) {
-		if (ohci->next_config_rom != ohci->config_rom) {
-			free_rom      = ohci->config_rom;
-			free_rom_bus  = ohci->config_rom_bus;
+	scoped_guard(spinlock_irq, &ohci->lock) {
+		ohci->generation = generation;
+		reg_write(ohci, OHCI1394_IntEventClear, OHCI1394_busReset);
+		reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_busReset);
+
+		if (ohci->quirks & QUIRK_RESET_PACKET)
+			ohci->request_generation = generation;
+
+		// This next bit is unrelated to the AT context stuff but we have to do it under the
+		// spinlock also. If a new config rom was set up before this reset, the old one is
+		// now no longer in use and we can free it. Update the config rom pointers to point
+		// to the current config rom and clear the next_config_rom pointer so a new update
+		// can take place.
+		if (ohci->next_config_rom != NULL) {
+			if (ohci->next_config_rom != ohci->config_rom) {
+				free_rom      = ohci->config_rom;
+				free_rom_bus  = ohci->config_rom_bus;
+			}
+			ohci->config_rom      = ohci->next_config_rom;
+			ohci->config_rom_bus  = ohci->next_config_rom_bus;
+			ohci->next_config_rom = NULL;
+
+			// Restore config_rom image and manually update config_rom registers.
+			// Writing the header quadlet will indicate that the config rom is ready,
+			// so we do that last.
+			reg_write(ohci, OHCI1394_BusOptions, be32_to_cpu(ohci->config_rom[2]));
+			ohci->config_rom[0] = ohci->next_header;
+			reg_write(ohci, OHCI1394_ConfigROMhdr, be32_to_cpu(ohci->next_header));
 		}
-		ohci->config_rom      = ohci->next_config_rom;
-		ohci->config_rom_bus  = ohci->next_config_rom_bus;
-		ohci->next_config_rom = NULL;
 
-		/*
-		 * Restore config_rom image and manually update
-		 * config_rom registers.  Writing the header quadlet
-		 * will indicate that the config rom is ready, so we
-		 * do that last.
-		 */
-		reg_write(ohci, OHCI1394_BusOptions,
-			  be32_to_cpu(ohci->config_rom[2]));
-		ohci->config_rom[0] = ohci->next_header;
-		reg_write(ohci, OHCI1394_ConfigROMhdr,
-			  be32_to_cpu(ohci->next_header));
-	}
-
-	if (param_remote_dma) {
-		reg_write(ohci, OHCI1394_PhyReqFilterHiSet, ~0);
-		reg_write(ohci, OHCI1394_PhyReqFilterLoSet, ~0);
+		if (param_remote_dma) {
+			reg_write(ohci, OHCI1394_PhyReqFilterHiSet, ~0);
+			reg_write(ohci, OHCI1394_PhyReqFilterLoSet, ~0);
+		}
 	}
 
-	spin_unlock_irq(&ohci->lock);
-
 	if (free_rom)
 		dmam_free_coherent(ohci->card.device, CONFIG_ROM_SIZE, free_rom, free_rom_bus);
 
@@ -2626,33 +2615,26 @@ static int ohci_set_config_rom(struct fw_card *card,
 	if (next_config_rom == NULL)
 		return -ENOMEM;
 
-	spin_lock_irq(&ohci->lock);
-
-	/*
-	 * If there is not an already pending config_rom update,
-	 * push our new allocation into the ohci->next_config_rom
-	 * and then mark the local variable as null so that we
-	 * won't deallocate the new buffer.
-	 *
-	 * OTOH, if there is a pending config_rom update, just
-	 * use that buffer with the new config_rom data, and
-	 * let this routine free the unused DMA allocation.
-	 */
-
-	if (ohci->next_config_rom == NULL) {
-		ohci->next_config_rom = next_config_rom;
-		ohci->next_config_rom_bus = next_config_rom_bus;
-		next_config_rom = NULL;
-	}
+	scoped_guard(spinlock_irq, &ohci->lock) {
+		// If there is not an already pending config_rom update, push our new allocation
+		// into the ohci->next_config_rom and then mark the local variable as null so that
+		// we won't deallocate the new buffer.
+		//
+		// OTOH, if there is a pending config_rom update, just use that buffer with the new
+		// config_rom data, and let this routine free the unused DMA allocation.
+		if (ohci->next_config_rom == NULL) {
+			ohci->next_config_rom = next_config_rom;
+			ohci->next_config_rom_bus = next_config_rom_bus;
+			next_config_rom = NULL;
+		}
 
-	copy_config_rom(ohci->next_config_rom, config_rom, length);
+		copy_config_rom(ohci->next_config_rom, config_rom, length);
 
-	ohci->next_header = config_rom[0];
-	ohci->next_config_rom[0] = 0;
+		ohci->next_header = config_rom[0];
+		ohci->next_config_rom[0] = 0;
 
-	reg_write(ohci, OHCI1394_ConfigROMmap, ohci->next_config_rom_bus);
-
-	spin_unlock_irq(&ohci->lock);
+		reg_write(ohci, OHCI1394_ConfigROMmap, ohci->next_config_rom_bus);
+	}
 
 	/* If we didn't use the DMA allocation, delete it. */
 	if (next_config_rom != NULL) {