Commit 155b7edb authored by Roger Pau Monne's avatar Roger Pau Monne Committed by Konrad Rzeszutek Wilk
Browse files

xen-blkfront: switch from llist to list 



The git commit f84adf49
(xen-blkfront: drop the use of llist_for_each_entry_safe)

was a stop-gate to fix a GCC4.1 bug. The appropiate way
is to actually use an list instead of using an llist.

As such this patch replaces the usage of llist with an
list.

Since we always manipulate the list while holding the io_lock, there's
no need for additional locking (llist used previously is safe to use
concurrently without additional locking).

Signed-off-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
CC: stable@vger.kernel.org
[v1: Redid the git commit description]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 217fd5e7

drivers/block/xen-blkfront.c

+18 −23
Original line number Diff line number Diff line
@@ -44,7 +44,7 @@ 
#include <linux/mutex.h>

#include <linux/scatterlist.h>

#include <linux/bitmap.h>

#include <linux/llist.h>

#include <linux/list.h>



#include <xen/xen.h>

#include <xen/xenbus.h>
@@ -68,7 +68,7 @@ enum blkif_state { 
struct grant {

	grant_ref_t gref;

	unsigned long pfn;

	struct llist_node node;

	struct list_head node;

};



struct blk_shadow {
@@ -105,7 +105,7 @@ struct blkfront_info 
	struct work_struct work;

	struct gnttab_free_callback callback;

	struct blk_shadow shadow[BLK_RING_SIZE];

	struct llist_head persistent_gnts;

	struct list_head persistent_gnts;

	unsigned int persistent_gnts_c;

	unsigned long shadow_free;

	unsigned int feature_flush;
@@ -371,10 +371,11 @@ static int blkif_queue_request(struct request *req) 
			lsect = fsect + (sg->length >> 9) - 1;



			if (info->persistent_gnts_c) {

				BUG_ON(llist_empty(&info->persistent_gnts));

				gnt_list_entry = llist_entry(

					llist_del_first(&info->persistent_gnts),

				BUG_ON(list_empty(&info->persistent_gnts));

				gnt_list_entry = list_first_entry(

				                      &info->persistent_gnts,

				                      struct grant, node);

				list_del(&gnt_list_entry->node);



				ref = gnt_list_entry->gref;

				buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
@@ -790,9 +791,8 @@ static void blkif_restart_queue(struct work_struct *work) 


static void blkif_free(struct blkfront_info *info, int suspend)

{

	struct llist_node *all_gnts;

	struct grant *persistent_gnt, *tmp;

	struct llist_node *n;

	struct grant *persistent_gnt;

	struct grant *n;



	/* Prevent new requests being issued until we fix things up. */

	spin_lock_irq(&info->io_lock);
@@ -804,20 +804,15 @@ static void blkif_free(struct blkfront_info *info, int suspend) 


	/* Remove all persistent grants */

	if (info->persistent_gnts_c) {

		all_gnts = llist_del_all(&info->persistent_gnts);

		persistent_gnt = llist_entry(all_gnts, typeof(*(persistent_gnt)), node);

		while (persistent_gnt) {

		list_for_each_entry_safe(persistent_gnt, n,

		                         &info->persistent_gnts, node) {

			list_del(&persistent_gnt->node);

			gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);

			__free_page(pfn_to_page(persistent_gnt->pfn));

			tmp = persistent_gnt;

			n = persistent_gnt->node.next;

			if (n)

				persistent_gnt = llist_entry(n, typeof(*(persistent_gnt)), node);

			else

				persistent_gnt = NULL;

			kfree(tmp);

			kfree(persistent_gnt);

			info->persistent_gnts_c--;

		}

		info->persistent_gnts_c = 0;

		BUG_ON(info->persistent_gnts_c != 0);

	}



	/* No more gnttab callback work. */
@@ -875,7 +870,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, 
	}

	/* Add the persistent grant into the list of free grants */

	for (i = 0; i < s->req.u.rw.nr_segments; i++) {

		llist_add(&s->grants_used[i]->node, &info->persistent_gnts);

		list_add(&s->grants_used[i]->node, &info->persistent_gnts);

		info->persistent_gnts_c++;

	}

}
@@ -1171,7 +1166,7 @@ static int blkfront_probe(struct xenbus_device *dev, 
	spin_lock_init(&info->io_lock);

	info->xbdev = dev;

	info->vdevice = vdevice;

	init_llist_head(&info->persistent_gnts);

	INIT_LIST_HEAD(&info->persistent_gnts);

	info->persistent_gnts_c = 0;

	info->connected = BLKIF_STATE_DISCONNECTED;

	INIT_WORK(&info->work, blkif_restart_queue);

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