* [PATCH] elevator: avoid redundant conditions
@ 2025-09-03 12:14 Liao Yuanhong
2025-09-04 2:33 ` Damien Le Moal
2025-09-04 6:05 ` Markus Elfring
0 siblings, 2 replies; 4+ messages in thread
From: Liao Yuanhong @ 2025-09-03 12:14 UTC (permalink / raw)
To: Jens Axboe, open list:BLOCK LAYER, open list; +Cc: Liao Yuanhong
While 'if (i < 0) ... else if (i >= 0) ...' is technically equivalent to
'if (i < 0) ... else ...', the latter is vastly easier to read because
it avoids writing out a condition that is unnecessary. Let's drop such
unnecessary conditions.
Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
---
block/elevator.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/elevator.c b/block/elevator.c
index fe96c6f4753c..3828c35f5753 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -240,7 +240,7 @@ void elv_rb_add(struct rb_root *root, struct request *rq)
if (blk_rq_pos(rq) < blk_rq_pos(__rq))
p = &(*p)->rb_left;
- else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
+ else
p = &(*p)->rb_right;
}
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] elevator: avoid redundant conditions
2025-09-03 12:14 [PATCH] elevator: avoid redundant conditions Liao Yuanhong
@ 2025-09-04 2:33 ` Damien Le Moal
2025-09-04 6:05 ` Markus Elfring
1 sibling, 0 replies; 4+ messages in thread
From: Damien Le Moal @ 2025-09-04 2:33 UTC (permalink / raw)
To: Liao Yuanhong, Jens Axboe, open list:BLOCK LAYER, open list
On 9/3/25 9:14 PM, Liao Yuanhong wrote:
> While 'if (i < 0) ... else if (i >= 0) ...' is technically equivalent to
> 'if (i < 0) ... else ...', the latter is vastly easier to read because
> it avoids writing out a condition that is unnecessary. Let's drop such
> unnecessary conditions.
>
> Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
--
Damien Le Moal
Western Digital Research
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] elevator: avoid redundant conditions
2025-09-04 6:05 ` Markus Elfring
@ 2025-09-04 6:05 ` Damien Le Moal
0 siblings, 0 replies; 4+ messages in thread
From: Damien Le Moal @ 2025-09-04 6:05 UTC (permalink / raw)
To: Markus Elfring, Liao Yuanhong, linux-block, Jens Axboe; +Cc: LKML
On 9/4/25 3:05 PM, Markus Elfring wrote:
> …
>> it avoids writing out a condition that is unnecessary. Let's drop such
>
> Thus?
>
>
>> unnecessary conditions.
>
> an unnecessary condition?
>
>
> Would a summary phrase like “Avoid redundant condition in elv_rb_add()”
> be nicer?
>
>
> …
>> +++ b/block/elevator.c
>> @@ -240,7 +240,7 @@ void elv_rb_add(struct rb_root *root, struct request *rq)
>>
>> if (blk_rq_pos(rq) < blk_rq_pos(__rq))
>> p = &(*p)->rb_left;
>> - else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
>> + else
>> p = &(*p)->rb_right;
>
>
> Would you dare to apply a conditional expression here?
>
> p = (blk_rq_pos(rq) < blk_rq_pos(__rq)) ? &(*p)->rb_left : &(*p)->rb_right;
This is far less readable.
>
>
> Regards,
> Markus
--
Damien Le Moal
Western Digital Research
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] elevator: avoid redundant conditions
2025-09-03 12:14 [PATCH] elevator: avoid redundant conditions Liao Yuanhong
2025-09-04 2:33 ` Damien Le Moal
@ 2025-09-04 6:05 ` Markus Elfring
2025-09-04 6:05 ` Damien Le Moal
1 sibling, 1 reply; 4+ messages in thread
From: Markus Elfring @ 2025-09-04 6:05 UTC (permalink / raw)
To: Liao Yuanhong, linux-block, Jens Axboe, Damien Le Moal; +Cc: LKML
…
> it avoids writing out a condition that is unnecessary. Let's drop such
Thus?
> unnecessary conditions.
an unnecessary condition?
Would a summary phrase like “Avoid redundant condition in elv_rb_add()”
be nicer?
…
> +++ b/block/elevator.c
> @@ -240,7 +240,7 @@ void elv_rb_add(struct rb_root *root, struct request *rq)
>
> if (blk_rq_pos(rq) < blk_rq_pos(__rq))
> p = &(*p)->rb_left;
> - else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
> + else
> p = &(*p)->rb_right;
Would you dare to apply a conditional expression here?
p = (blk_rq_pos(rq) < blk_rq_pos(__rq)) ? &(*p)->rb_left : &(*p)->rb_right;
Regards,
Markus
^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-09-04 2:33 ` Damien Le Moal
2025-09-04 6:05 ` Markus Elfring
2025-09-04 6:05 ` Damien Le Moal
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