1 files changed, 28 insertions, 13 deletions

diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index 7083bcc1b9c7..5045156c5313 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -57,6 +57,8 @@ static LIST_HEAD(descriptor_list);
 static int descriptor_count;
 
 static __be32 tmp_config_rom[256];
+/* ROM header, bus info block, root dir header, capabilities = 7 quadlets */
+static size_t config_rom_length = 1 + 4 + 1 + 1;
 
 #define BIB_CRC(v)              ((v) <<  0)
 #define BIB_CRC_LENGTH(v)       ((v) << 16)
@@ -73,7 +75,7 @@ static __be32 tmp_config_rom[256];
 #define BIB_CMC                 ((1) << 30)
 #define BIB_IMC                 ((1) << 31)
 
-static size_t generate_config_rom(struct fw_card *card, __be32 *config_rom)
+static void generate_config_rom(struct fw_card *card, __be32 *config_rom)
 {
         struct fw_descriptor *desc;
         int i, j, k, length;
@@ -130,23 +132,30 @@ static size_t generate_config_rom(struct fw_card *card, __be32 *config_rom)
         for (i = 0; i < j; i += length + 1)
                 length = fw_compute_block_crc(config_rom + i);
 
-        return j;
+        WARN_ON(j != config_rom_length);
 }
 
 static void update_config_roms(void)
 {
         struct fw_card *card;
-        size_t length;
 
         list_for_each_entry (card, &card_list, link) {
-                length = generate_config_rom(card, tmp_config_rom);
-                card->driver->set_config_rom(card, tmp_config_rom, length);
+                generate_config_rom(card, tmp_config_rom);
+                card->driver->set_config_rom(card, tmp_config_rom,
+                                             config_rom_length);
         }
 }
 
+static size_t required_space(struct fw_descriptor *desc)
+{
+        /* descriptor + entry into root dir + optional immediate entry */
+        return desc->length + 1 + (desc->immediate > 0 ? 1 : 0);
+}
+
 int fw_core_add_descriptor(struct fw_descriptor *desc)
 {
         size_t i;
+        int ret;
 
         /*
          * Check descriptor is valid; the length of all blocks in the
@@ -162,15 +171,21 @@ int fw_core_add_descriptor(struct fw_descriptor *desc)
 
         mutex_lock(&card_mutex);
 
-        list_add_tail(&desc->link, &descriptor_list);
-        descriptor_count++;
-        if (desc->immediate > 0)
+        if (config_rom_length + required_space(desc) > 256) {
+                ret = -EBUSY;
+        } else {
+                list_add_tail(&desc->link, &descriptor_list);
+                config_rom_length += required_space(desc);
                 descriptor_count++;
-        update_config_roms();
+                if (desc->immediate > 0)
+                        descriptor_count++;
+                update_config_roms();
+                ret = 0;
+        }
 
         mutex_unlock(&card_mutex);
 
-        return 0;
+        return ret;
 }
 EXPORT_SYMBOL(fw_core_add_descriptor);
 
@@ -179,6 +194,7 @@ void fw_core_remove_descriptor(struct fw_descriptor *desc)
         mutex_lock(&card_mutex);
 
         list_del(&desc->link);
+        config_rom_length -= required_space(desc);
         descriptor_count--;
         if (desc->immediate > 0)
                 descriptor_count--;
@@ -428,7 +444,6 @@ EXPORT_SYMBOL(fw_card_initialize);
 int fw_card_add(struct fw_card *card,
                 u32 max_receive, u32 link_speed, u64 guid)
 {
-        size_t length;
         int ret;
 
         card->max_receive = max_receive;
@@ -437,8 +452,8 @@ int fw_card_add(struct fw_card *card,
 
         mutex_lock(&card_mutex);
 
-        length = generate_config_rom(card, tmp_config_rom);
-        ret = card->driver->enable(card, tmp_config_rom, length);
+        generate_config_rom(card, tmp_config_rom);
+        ret = card->driver->enable(card, tmp_config_rom, config_rom_length);
         if (ret == 0)
                 list_add_tail(&card->link, &card_list);