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driver core: Remove completion from struct klist_node 

Removing the completion from klist_node reduces its size from 64 bytes
to 28 on x86-64.  To maintain the semantics of klist_remove(), we add
a single list of klist nodes which are pending deletion and scan them.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Matthew Wilcox 2008-10-16 14:57:54 -06:00 committed by Greg Kroah-Hartman
parent 929d2fa595
commit 210272a284
2 changed files with 40 additions and 5 deletions
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2
include/linux/klist.h
View File

@ -13,7 +13,6 @@
#define _LINUX_KLIST_H
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/kref.h>
#include <linux/list.h>
@ -41,7 +40,6 @@ struct klist_node {
void *n_klist; /* never access directly */
struct list_head n_node;
struct kref n_ref;
struct completion n_removed;
};
extern void klist_add_tail(struct klist_node *n, struct klist *k);

43
lib/klist.c
View File

@ -36,6 +36,7 @@
#include <linux/klist.h>
#include <linux/module.h>
#include <linux/sched.h>
/*
* Use the lowest bit of n_klist to mark deleted nodes and exclude
@ -108,7 +109,6 @@ static void add_tail(struct klist *k, struct klist_node *n)
static void klist_node_init(struct klist *k, struct klist_node *n)
{
INIT_LIST_HEAD(&n->n_node);
init_completion(&n->n_removed);
kref_init(&n->n_ref);
knode_set_klist(n, k);
if (k->get)
@ -171,13 +171,34 @@ void klist_add_before(struct klist_node *n, struct klist_node *pos)
}
EXPORT_SYMBOL_GPL(klist_add_before);
struct klist_waiter {
struct list_head list;
struct klist_node *node;
struct task_struct *process;
int woken;
};
static DEFINE_SPINLOCK(klist_remove_lock);
static LIST_HEAD(klist_remove_waiters);
static void klist_release(struct kref *kref)
{
struct klist_waiter *waiter, *tmp;
struct klist_node *n = container_of(kref, struct klist_node, n_ref);
WARN_ON(!knode_dead(n));
list_del(&n->n_node);
complete(&n->n_removed);
spin_lock(&klist_remove_lock);
list_for_each_entry_safe(waiter, tmp, &klist_remove_waiters, list) {
if (waiter->node != n)
continue;
waiter->woken = 1;
mb();
wake_up_process(waiter->process);
list_del(&waiter->list);
}
spin_unlock(&klist_remove_lock);
knode_set_klist(n, NULL);
}
@ -217,8 +238,24 @@ EXPORT_SYMBOL_GPL(klist_del);
*/
void klist_remove(struct klist_node *n)
{
struct klist_waiter waiter;
waiter.node = n;
waiter.process = current;
waiter.woken = 0;
spin_lock(&klist_remove_lock);
list_add(&waiter.list, &klist_remove_waiters);
spin_unlock(&klist_remove_lock);
klist_del(n);
wait_for_completion(&n->n_removed);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (waiter.woken)
break;
schedule();
}
__set_current_state(TASK_RUNNING);
}
EXPORT_SYMBOL_GPL(klist_remove);