firewire: replace static ROM cache by allocated cache

read_bus_info_block() is repeatedly called by workqueue jobs.
These will step on each others toes eventually if there are multiple
workqueue threads, and we end up with corrupt config ROM images.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/fw-device.c

@@ -400,6 +400,9 @@ read_rom(struct fw_device *device, int generation, int index, u32 *data)
 	return callback_data.rcode;
 }
 
+#define READ_BIB_ROM_SIZE	256
+#define READ_BIB_STACK_SIZE	16
+
 /*
  * Read the bus info block, perform a speed probe, and read all of the rest of
  * the config ROM.  We do all this with a cached bus generation.  If the bus
@@ -409,16 +412,23 @@ read_rom(struct fw_device *device, int generation, int index, u32 *data)
  */
 static int read_bus_info_block(struct fw_device *device, int generation)
 {
-	static u32 rom[256];
-	u32 stack[16], sp, key;
-	int i, end, length;
+	u32 *rom, *stack;
+	u32 sp, key;
+	int i, end, length, ret = -1;
+
+	rom = kmalloc(sizeof(*rom) * READ_BIB_ROM_SIZE +
+		      sizeof(*stack) * READ_BIB_STACK_SIZE, GFP_KERNEL);
+	if (rom == NULL)
+		return -ENOMEM;
+
+	stack = &rom[READ_BIB_ROM_SIZE];
 
 	device->max_speed = SCODE_100;
 
 	/* First read the bus info block. */
 	for (i = 0; i < 5; i++) {
 		if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
-			return -1;
+			goto out;
 		/*
 		 * As per IEEE1212 7.2, during power-up, devices can
 		 * reply with a 0 for the first quadlet of the config
@@ -428,7 +438,7 @@ static int read_bus_info_block(struct fw_device *device, int generation)
 		 * retry mechanism will try again later.
 		 */
 		if (i == 0 && rom[i] == 0)
-			return -1;
+			goto out;
 	}
 
 	device->max_speed = device->node->max_speed;
@@ -478,26 +488,26 @@ static int read_bus_info_block(struct fw_device *device, int generation)
 		 */
 		key = stack[--sp];
 		i = key & 0xffffff;
-		if (i >= ARRAY_SIZE(rom))
+		if (i >= READ_BIB_ROM_SIZE)
 			/*
 			 * The reference points outside the standard
 			 * config rom area, something's fishy.
 			 */
-			return -1;
+			goto out;
 
 		/* Read header quadlet for the block to get the length. */
 		if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
-			return -1;
+			goto out;
 		end = i + (rom[i] >> 16) + 1;
 		i++;
-		if (end > ARRAY_SIZE(rom))
+		if (end > READ_BIB_ROM_SIZE)
 			/*
 			 * This block extends outside standard config
 			 * area (and the array we're reading it
 			 * into).  That's broken, so ignore this
 			 * device.
 			 */
-			return -1;
+			goto out;
 
 		/*
 		 * Now read in the block.  If this is a directory
@@ -507,9 +517,9 @@ static int read_bus_info_block(struct fw_device *device, int generation)
 		while (i < end) {
 			if (read_rom(device, generation, i, &rom[i]) !=
 			    RCODE_COMPLETE)
-				return -1;
+				goto out;
 			if ((key >> 30) == 3 && (rom[i] >> 30) > 1 &&
-			    sp < ARRAY_SIZE(stack))
+			    sp < READ_BIB_STACK_SIZE)
 				stack[sp++] = i + rom[i];
 			i++;
 		}
@@ -519,11 +529,14 @@ static int read_bus_info_block(struct fw_device *device, int generation)
 
 	device->config_rom = kmalloc(length * 4, GFP_KERNEL);
 	if (device->config_rom == NULL)
-		return -1;
+		goto out;
 	memcpy(device->config_rom, rom, length * 4);
 	device->config_rom_length = length;
+	ret = 0;
+ out:
+	kfree(rom);
 
-	return 0;
+	return ret;
 }
 
 static void fw_unit_release(struct device *dev)