Le mercredi 30 mars 2011 Ã 14:24 +0300, Daniel Baluta a Ãcrit :
> We have:
>
> > UDP hash table entries: 128 (order: 0, 4096 bytes)
> > CONFIG_BASE_SMALL=0
>
> udp_table_init looks like:
>
> if (!CONFIG_BASE_SMALL)
> table->hash = alloc_large_system_hash(name, .. &table->mask);
> /*
> * Make sure hash table has the minimum size
> */
>
> Since CONFIG_BASE_SMALL is 0, we are allocating the hash using
> alloc_large_system
> Then:
> if (CONFIG_BASE_SMALL || table->mask < UDP_HTABLE_SIZE_MIN - 1) {
> table->hash = kmalloc();
>
> table->mask is 127, and UDP_HTABLE_SIZE_MIN is 256, so we are allocating again
> table->hash without freeing already allocated memory.
>
> We could free table->hash, before allocating the memory with kmalloc.
> I don't fully understand the condition table->mask < UDP_HTABLE_SIZE_MIN - 1.
>
> Eric?
There is nothing special. UDP algo needs a minimum hash table that
alloc_large_system_hash() was not able to provide (???)
As you spotted, there is no free_large-system_hash(), so we 'leak' the
small hash table.
If machine has not enough memory to provide such a small hash table, I
suggest using CONFIG_BASE_SMALL, since :
#define UDP_HTABLE_SIZE_MIN (CONFIG_BASE_SMALL ? 128 : 256)
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