nlmsg_failure on a function in some machines

[Giacomo <delleceste@gmail.com>]

Good morning to all.
I noticed that the following piece of code, while working on many machines,
goes to NLMSG_PUT nlmsg_failure goto label in some cases.

Is there something wrong with it?

Thanks in advance.

Code follows here:

 /* buf is a buffer containing the data to be sent to userspace,
  * numbytes is the length of the data contained in buf
 */
 struct sk_buff *build_packet(void *buf, int numbytes)
    4 {
    5   struct sk_buff *skb_to_user;
    6   struct nlmsghdr *nlh;
    7   void *data;
    8   int len = NLMSG_SPACE(numbytes);
    9    /* allocate socket buffer space atomically */
   10   skb_to_user = alloc_skb(len, GFP_ATOMIC);
   11
   12   if(skb_to_user == NULL)
   13     return NULL;
   14
   15   nlh = NLMSG_PUT(skb_to_user, 0, 0, 0, len);
   16   if(NLMSG_OK(nlh, NLMSG_LENGTH(len)))
   17   {
   18     nlh->nlmsg_len = NLMSG_LENGTH(len);
   19     data = NLMSG_DATA(nlh);
   20     memcpy(data, buf, numbytes);
   21   }
   22   else
   23   {
   24     printk("IPFIRE: NLMSG_OK failed: NLMSG_LENGTH(%d) is %d,
NLMSG_SPACE(numbytes %d) is %d in build_packet(), "
   25       "ipfi_netl_packet_builder.c\n", len, NLMSG_LENGTH(len),
numbytes, NLMSG_SPACE(numbytes));
   26     return NULL;
   27   }
   28   return skb_to_user;      /* return just allocated socket buffer */
   29
   30   nlmsg_failure:  /* NLMSG_PUT fails */
   31
   32   printk("IPFIRE: nlmsg failure in build_packet() - %d bytes -
ipfi_netl_packet_builder.c\n", len);
   33   return NULL;
   34 }
   35

  As told before, in some machines NLMSG_PUT goes to nlmsg_failure label.

Thanks in advance for any suggestion.

Best regards

Giacomo


-- 
Giacomo S.
http://www.giacomos.it

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