Hi Qing,
On 4/5/07, qingxiaoming <qing_xiaoming@xxxxxxxxx> wrote:
Dear all:
I am reading the function set_shrinker() in mm/vmscan.c of V2.6.12, and I
have a question about the not initialization of list_head,
/*
* Add a shrinker callback to be called from the vm
*/
struct shrinker *set_shrinker(int seeks, shrinker_t theshrinker)
{
struct shrinker *shrinker;
shrinker = kmalloc(sizeof(*shrinker), GFP_KERNEL);
if (shrinker) {
shrinker->shrinker = theshrinker;
shrinker->seeks = seeks;
shrinker->nr = 0;
down_write(&shrinker_rwsem);
list_add_tail(&shrinker->list, &shrinker_list);
up_write(&shrinker_rwsem);
}
return shrinker;
}
As above, the shrinker is allocated from kmalloc, coming from slab
allocator,the list in shrinker is not initialized, directly list_add_tail()
to shrinker_list, don't need to INIT_LIST_HEAD(shrinker->list)?
IMHO, the linked list is not headed by shrinker->list, rather by
shrinker_list. So the statement
list_add_tail(&shrinker->list, &shrinker_list);
is actually adding shrinker to the list shrinker_list. The shrinker->
list is merely a pointer to help in atttaching the node to the list.
Thanks,
Rajat
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