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[PATCH] cfq-iosched: move tasklist walk to elevator.c

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We're trying to get rid of as much as possible tasklist walks, or at
least moving them to core code.  This patch falls into the second
category.

Instead of walking the tasklist in cfq-iosched move that into
elv_unregister.  The added benefit is that with this change the as
ioscheduler might be might unloadable more easily aswell.

The new code uses read_lock instead of read_lock_irq because the
tasklist_lock only needs irq disabling for writers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Hellwig 2005-10-30 15:01:39 -08:00 committed by Linus Torvalds
parent a8db2db1e6
commit 83521d3eb8
3 changed files with 23 additions and 22 deletions
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2
drivers/block/as-iosched.c
View file

@ -1973,8 +1973,8 @@ static int __init as_init(void)
static void __exit as_exit(void)
{
kmem_cache_destroy(arq_pool);
elv_unregister(&iosched_as);
kmem_cache_destroy(arq_pool);
}
module_init(as_init);

22
drivers/block/cfq-iosched.c
View file

@ -2418,28 +2418,8 @@ static int __init cfq_init(void)
static void __exit cfq_exit(void)
{
struct task_struct *g, *p;
unsigned long flags;
read_lock_irqsave(&tasklist_lock, flags);
/*
* iterate each process in the system, removing our io_context
*/
do_each_thread(g, p) {
struct io_context *ioc = p->io_context;
if (ioc && ioc->cic) {
ioc->cic->exit(ioc->cic);
cfq_free_io_context(ioc->cic);
ioc->cic = NULL;
}
} while_each_thread(g, p);
read_unlock_irqrestore(&tasklist_lock, flags);
cfq_slab_kill();
elv_unregister(&iosched_cfq);
cfq_slab_kill();
}
module_init(cfq_init);

21
drivers/block/elevator.c
View file

@ -642,6 +642,27 @@ EXPORT_SYMBOL_GPL(elv_register);
void elv_unregister(struct elevator_type *e)
{
struct task_struct *g, *p;
/*
* Iterate every thread in the process to remove the io contexts.
*/
read_lock(&tasklist_lock);
do_each_thread(g, p) {
struct io_context *ioc = p->io_context;
if (ioc && ioc->cic) {
ioc->cic->exit(ioc->cic);
ioc->cic->dtor(ioc->cic);
ioc->cic = NULL;
}
if (ioc && ioc->aic) {
ioc->aic->exit(ioc->aic);
ioc->aic->dtor(ioc->aic);
ioc->aic = NULL;
}
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
spin_lock_irq(&elv_list_lock);
list_del_init(&e->list);
spin_unlock_irq(&elv_list_lock);