linux-kernel - [PATCH 2/2] [SCSI] libiscsi: replace kfifo_init with kfifo

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Date:	Mon, 19 Nov 2012 16:58:59 +0800
From:	Yuanhan Liu <yuanhan.liu@...ux.intel.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-scsi@...r.kernel.org,
	Yuanhan Liu <yuanhan.liu@...ux.intel.com>,
	Mike Christie <michaelc@...wisc.edu>,
	"James E.J. Bottomley" <JBottomley@...allels.com>,
	iscsi list <open-iscsi@...glegroups.com>,
	Stefani Seibold <stefani@...bold.net>
Subject: [PATCH 2/2] [SCSI] libiscsi: replace kfifo_init with kfifo_alloc

kfifo_init will use a pre-allocated buffer as fifo buffer; the buffer
size is determinted at caller side. While, kfifo will maintain a real
kfifo buffer size(power of 2 aligned). So, the two size may not be
equal.

So, to be safe. We should use kfifo_alloc instead. git grep 'kfifo_init\>'
shows that this is one user of kfifo_init(2 in total).

Replace it with kfifo_alloc, as I propose to remove kfifo_init API
later.

Besides that, I refactored the code a bit with the style used in
libsrp.c: allocated items once by kcalloc.

Cc: Mike Christie <michaelc@...wisc.edu>
Cc: James E.J. Bottomley <JBottomley@...allels.com>
Cc: iscsi list <open-iscsi@...glegroups.com>
Cc: Stefani Seibold <stefani@...bold.net>
Signed-off-by: Yuanhan Liu <yuanhan.liu@...ux.intel.com>
---
 drivers/scsi/libiscsi.c |   59 ++++++++++++++++++++++++-----------------------
 include/scsi/libiscsi.h |    4 +-
 2 files changed, 32 insertions(+), 31 deletions(-)

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 82c3fd4..8e60f1f 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -2485,51 +2485,52 @@ EXPORT_SYMBOL_GPL(iscsi_eh_recover_target);
 int
 iscsi_pool_init(struct iscsi_pool *q, int max, void ***items, int item_size)
 {
-	int i, num_arrays = 1;
-
-	memset(q, 0, sizeof(*q));
+	int i;
+	int ret;
+	void *item;
 
-	q->max = max;
+	ret = -ENOMEM;
+	q->pool = kcalloc(max, item_size, GFP_KERNEL);
+	if (!q->pool)
+		goto err_out;
 
-	/* If the user passed an items pointer, he wants a copy of
-	 * the array. */
-	if (items)
-		num_arrays++;
-	q->pool = kzalloc(num_arrays * max * sizeof(void*), GFP_KERNEL);
-	if (q->pool == NULL)
-		return -ENOMEM;
+	ret = kfifo_alloc(&q->queue, max * sizeof(void *), GFP_KERNEL);
+	if (ret < 0)
+		goto free_pool;
 
-	kfifo_init(&q->queue, (void*)q->pool, max * sizeof(void*));
-
-	for (i = 0; i < max; i++) {
-		q->pool[i] = kzalloc(item_size, GFP_KERNEL);
-		if (q->pool[i] == NULL) {
-			q->max = i;
-			goto enomem;
+	q->items_ptr = NULL;
+	/* If the user passed an items pointer, he wants a copy of the array */
+	if (items) {
+		q->items_ptr = kcalloc(max, sizeof(void *), GFP_KERNEL);
+		if (!q->items_ptr) {
+			ret = -ENOMEM;
+			goto free_fifo;
 		}
-		kfifo_in(&q->queue, (void*)&q->pool[i], sizeof(void*));
+		*items = q->items_ptr;
 	}
 
-	if (items) {
-		*items = q->pool + max;
-		memcpy(*items, q->pool, max * sizeof(void *));
+	for (i = 0, item = q->pool; i < max; i++, item += item_size) {
+		kfifo_in(&q->queue, &item, sizeof(void *));
+		if (q->items_ptr)
+			q->items_ptr[i] = item;
 	}
 
 	return 0;
 
-enomem:
-	iscsi_pool_free(q);
-	return -ENOMEM;
+free_fifo:
+	kfifo_free(&q->queue);
+free_pool:
+	kfree(q->pool);
+err_out:
+	return ret;
 }
 EXPORT_SYMBOL_GPL(iscsi_pool_init);
 
 void iscsi_pool_free(struct iscsi_pool *q)
 {
-	int i;
-
-	for (i = 0; i < q->max; i++)
-		kfree(q->pool[i]);
 	kfree(q->pool);
+	kfree(q->items_ptr);
+	kfifo_free(&q->queue);
 }
 EXPORT_SYMBOL_GPL(iscsi_pool_free);
 
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 6e33386..c4262c6 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -231,8 +231,8 @@ struct iscsi_conn {
 
 struct iscsi_pool {
 	struct kfifo		queue;		/* FIFO Queue */
-	void			**pool;		/* Pool of elements */
-	int			max;		/* Max number of elements */
+	void			*pool;		/* Pool of elements */
+	void			**items_ptr;	/* element pointers */
 };
 
 /* Session's states */
-- 
1.7.7.6

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