[PATCH 1/2] xt_u32 (kernel) - match arbitrary bits and bytes of a packet

[Jan Engelhardt]

Hi,

On Jun 3 2007 19:23, Patrick McHardy wrote:
>Also
>
>	u_int32_t min;
>	u_int32_t max;
>
>please (and everywhere else of course).

Might get a bit verbose.

Question:
ipt_u32/xt_u32 uses a spinlock_bh to protect the buffer to which a packet
is copied to before analyzing.

>> +	spin_lock_bh(&xt_u32_lock);
>> +
>> +	head = skb_header_pointer(skb, 0, min(skb->len,
>> +	       sizeof(xt_u32_buffer)), xt_u32_buffer);

I'd like to hear opinions about:

 * open coding skb_header_pointer

   In the "hlen - offset >= len" case in skb_header_pointer(), it just
   returns a pointer to the existing skb without copying, in which
   case we would not need to take a lock at all.

 * use percpu buffers, with or without opencoding skb_header_pointer
   so that cpus/threads do not have to wait for another -m u32 to finish.


	Jan
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