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Commit 210272a2 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Greg Kroah-Hartman
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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: default avatarMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 929d2fa5

include/linux/klist.h

+0 −2
Original line number Diff line number Diff line
@@ -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);

lib/klist.c

+40 −3
Original line number Diff line number Diff line
@@ -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);