[PATCH V2 4/7] null_blk: don't use magic numbers in the code

[Chaitanya Kulkarni <kch@xxxxxxxxxx>]

Insteasd of using the hardcoded value use meaningful macro for tag
available value of -1U in get_tag() and __alloc_cmd().

While at it return early on error to get rid of the extra indentation
in __alloc_cmd().

Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
---
 drivers/block/null_blk/main.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 84f5ca0cc79c..db849e6bc475 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -24,6 +24,8 @@
 #define TICKS_PER_SEC		50ULL
 #define TIMER_INTERVAL		(NSEC_PER_SEC / TICKS_PER_SEC)
 
+#define NULL_REQ_TAG_NOT_AVAILABLE (-1U)
+
 #ifdef CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION
 static DECLARE_FAULT_ATTR(null_timeout_attr);
 static DECLARE_FAULT_ATTR(null_requeue_attr);
@@ -730,7 +732,7 @@ static unsigned int get_tag(struct nullb_queue *nq)
 	do {
 		tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
 		if (tag >= nq->queue_depth)
-			return -1U;
+			return NULL_REQ_TAG_NOT_AVAILABLE;
 	} while (test_and_set_bit_lock(tag, nq->tag_map));
 
 	return tag;
@@ -749,21 +751,19 @@ static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq, struct bio *bio)
 	unsigned int tag;
 
 	tag = get_tag(nq);
-	if (tag != -1U) {
-		cmd = &nq->cmds[tag];
-		cmd->tag = tag;
-		cmd->error = BLK_STS_OK;
-		cmd->nq = nq;
-		cmd->bio = bio;
-		if (nq->dev->irqmode == NULL_IRQ_TIMER) {
-			hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
-				     HRTIMER_MODE_REL);
-			cmd->timer.function = null_cmd_timer_expired;
-		}
-		return cmd;
+	if (tag == NULL_REQ_TAG_NOT_AVAILABLE)
+		return NULL;
+	cmd = &nq->cmds[tag];
+	cmd->tag = tag;
+	cmd->error = BLK_STS_OK;
+	cmd->nq = nq;
+	cmd->bio = bio;
+	if (nq->dev->irqmode == NULL_IRQ_TIMER) {
+		hrtimer_init(&cmd->timer, CLOCK_MONOTONIC,
+				HRTIMER_MODE_REL);
+		cmd->timer.function = null_cmd_timer_expired;
 	}
-
-	return NULL;
+	return cmd;
 }
 
 static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, struct bio *bio)
-- 
2.29.0