2022-10-05 03:50:41

by Chaitanya Kulkarni

Subject: [PATCH 5/6] null_blk: don't use magic numbers in the code

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 <[email protected]>
---
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 765c1ca0edf5..eda5050d6dee 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

2022-10-05 06:20:25

by Damien Le Moal

Subject: Re: [PATCH 5/6] null_blk: don't use magic numbers in the code

On 10/5/22 12:17, Chaitanya Kulkarni wrote:
> 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 <[email protected]>

Reviewed-by: Damien Le Moal <[email protected]>

> ---
> 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 765c1ca0edf5..eda5050d6dee 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)

--
Damien Le Moal
Western Digital Research