[PATCH v1] atm: idt77252: fix build broken on amd64

[Tong Zhang]

  idt77252 is broken and wont load on amd64 systems
  modprobe idt77252 shows the following

    idt77252_init: skb->cb is too small (48 < 56)

  Add packed attribute to struct idt77252_skb_prv and struct atm_skb_data
  so that the total size can be <= sizeof(skb->cb)
  Also convert runtime size check to buildtime size check in
  idt77252_init()

Signed-off-by: Tong Zhang <ztong0...@gmail.com>
---
 drivers/atm/idt77252.c | 11 +----------
 drivers/atm/idt77252.h |  2 +-
 include/linux/atmdev.h |  2 +-
 3 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/atm/idt77252.c b/drivers/atm/idt77252.c
index 5f0472c18bcb..0c13cac903de 100644
--- a/drivers/atm/idt77252.c
+++ b/drivers/atm/idt77252.c
@@ -3743,16 +3743,7 @@ static int __init idt77252_init(void)
        struct sk_buff *skb;
 
        printk("%s: at %p\n", __func__, idt77252_init);
-
-       if (sizeof(skb->cb) < sizeof(struct atm_skb_data) +
-                             sizeof(struct idt77252_skb_prv)) {
-               printk(KERN_ERR "%s: skb->cb is too small (%lu < %lu)\n",
-                      __func__, (unsigned long) sizeof(skb->cb),
-                      (unsigned long) sizeof(struct atm_skb_data) +
-                                      sizeof(struct idt77252_skb_prv));
-               return -EIO;
-       }
-
+       BUILD_BUG_ON(sizeof(skb->cb) < sizeof(struct idt77252_skb_prv) + 
sizeof(struct atm_skb_data));
        return pci_register_driver(&idt77252_driver);
 }
 
diff --git a/drivers/atm/idt77252.h b/drivers/atm/idt77252.h
index 9339197d701c..b059d31364dd 100644
--- a/drivers/atm/idt77252.h
+++ b/drivers/atm/idt77252.h
@@ -789,7 +789,7 @@ struct idt77252_skb_prv {
        struct scqe     tbd;    /* Transmit Buffer Descriptor */
        dma_addr_t      paddr;  /* DMA handle */
        u32             pool;   /* sb_pool handle */
-};
+} __packed;
 
 #define IDT77252_PRV_TBD(skb)  \
        (((struct idt77252_skb_prv *)(ATM_SKB(skb)+1))->tbd)
diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
index d7493016cd46..60cd25c0461b 100644
--- a/include/linux/atmdev.h
+++ b/include/linux/atmdev.h
@@ -207,7 +207,7 @@ struct atm_skb_data {
        struct atm_vcc  *vcc;           /* ATM VCC */
        unsigned long   atm_options;    /* ATM layer options */
        unsigned int    acct_truesize;  /* truesize accounted to vcc */
-};
+} __packed;
 
 #define VCC_HTABLE_SIZE 32
 
-- 
2.25.1