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From:   Yury Norov <yury.norov@gmail.com>
To:     linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Ming Lei <ming.lei@redhat.com>,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        Chengming Zhou <zhouchengming@bytedance.com>,
        Nitesh Shetty <nj.shetty@samsung.com>,
        Akinobu Mita <akinobu.mita@gmail.com>,
        Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
        Yury Norov <yury.norov@gmail.com>, linux-block@vger.kernel.org
Cc:     Jan Kara <jack@suse.cz>,
        Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>,
        Matthew Wilcox <willy@infradead.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>,
        Alexey Klimov <klimov.linux@gmail.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Sergey Shtylyov <s.shtylyov@omp.ru>
Subject: [PATCH v3 24/35] block: null_blk: replace get_tag() with a generic find_and_set_bit_lock()
Date:   Mon, 11 Dec 2023 18:27:38 -0800
Message-Id: <20231212022749.625238-25-yury.norov@gmail.com>
In-Reply-To: <20231212022749.625238-1-yury.norov@gmail.com>
References: <20231212022749.625238-1-yury.norov@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

get_tag() opencodes find_and_set_bit(). Simplify the code by getting
rid of it.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 drivers/block/null_blk/main.c | 41 +++++++++++------------------------
 1 file changed, 13 insertions(+), 28 deletions(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 3021d58ca51c..671dbb9ab928 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -760,19 +760,6 @@ static void put_tag(struct nullb_queue *nq, unsigned int tag)
 		wake_up(&nq->wait);
 }
 
-static unsigned int get_tag(struct nullb_queue *nq)
-{
-	unsigned int tag;
-
-	do {
-		tag = find_first_zero_bit(nq->tag_map, nq->queue_depth);
-		if (tag >= nq->queue_depth)
-			return -1U;
-	} while (test_and_set_bit_lock(tag, nq->tag_map));
-
-	return tag;
-}
-
 static void free_cmd(struct nullb_cmd *cmd)
 {
 	put_tag(cmd->nq, cmd->tag);
@@ -782,24 +769,22 @@ static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer);
 
 static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
 {
+	unsigned int tag = find_and_set_bit_lock(nq->tag_map, nq->queue_depth);
 	struct nullb_cmd *cmd;
-	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;
-		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 >= nq->queue_depth)
+		return NULL;
+
+	cmd = &nq->cmds[tag];
+	cmd->tag = tag;
+	cmd->error = BLK_STS_OK;
+	cmd->nq = nq;
+	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)
-- 
2.40.1