* [PATCH 1/1] RDMA/cm: Delete two redundant condition branches
@ 2021-05-10 9:08 Zhen Lei
2021-05-10 9:50 ` Leon Romanovsky
2021-05-11 19:56 ` Jason Gunthorpe
0 siblings, 2 replies; 5+ messages in thread
From: Zhen Lei @ 2021-05-10 9:08 UTC (permalink / raw)
To: Doug Ledford, Jason Gunthorpe, linux-rdma; +Cc: Zhen Lei
The statement of the last "if (xxx)" branch is the same as the "else"
branch. Delete it to simplify code.
No functional change.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
drivers/infiniband/core/cm.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 0ead0d223154011..510beb25f5b8a0b 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -668,8 +668,6 @@ static struct cm_id_private *cm_insert_listen(struct cm_id_private *cm_id_priv,
link = &(*link)->rb_right;
else if (be64_lt(service_id, cur_cm_id_priv->id.service_id))
link = &(*link)->rb_left;
- else if (be64_gt(service_id, cur_cm_id_priv->id.service_id))
- link = &(*link)->rb_right;
else
link = &(*link)->rb_right;
}
@@ -700,8 +698,6 @@ static struct cm_id_private *cm_find_listen(struct ib_device *device,
node = node->rb_right;
else if (be64_lt(service_id, cm_id_priv->id.service_id))
node = node->rb_left;
- else if (be64_gt(service_id, cm_id_priv->id.service_id))
- node = node->rb_right;
else
node = node->rb_right;
}
--
2.26.0.106.g9fadedd
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 1/1] RDMA/cm: Delete two redundant condition branches
2021-05-10 9:08 [PATCH 1/1] RDMA/cm: Delete two redundant condition branches Zhen Lei
@ 2021-05-10 9:50 ` Leon Romanovsky
2021-05-11 19:56 ` Jason Gunthorpe
1 sibling, 0 replies; 5+ messages in thread
From: Leon Romanovsky @ 2021-05-10 9:50 UTC (permalink / raw)
To: Zhen Lei; +Cc: Doug Ledford, Jason Gunthorpe, linux-rdma
On Mon, May 10, 2021 at 05:08:40PM +0800, Zhen Lei wrote:
> The statement of the last "if (xxx)" branch is the same as the "else"
> branch. Delete it to simplify code.
>
> No functional change.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
> drivers/infiniband/core/cm.c | 4 ----
> 1 file changed, 4 deletions(-)
>
Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/1] RDMA/cm: Delete two redundant condition branches
2021-05-10 9:08 [PATCH 1/1] RDMA/cm: Delete two redundant condition branches Zhen Lei
2021-05-10 9:50 ` Leon Romanovsky
@ 2021-05-11 19:56 ` Jason Gunthorpe
2021-05-12 1:35 ` Leizhen (ThunderTown)
1 sibling, 1 reply; 5+ messages in thread
From: Jason Gunthorpe @ 2021-05-11 19:56 UTC (permalink / raw)
To: Zhen Lei; +Cc: Doug Ledford, linux-rdma
On Mon, May 10, 2021 at 05:08:40PM +0800, Zhen Lei wrote:
> The statement of the last "if (xxx)" branch is the same as the "else"
> branch. Delete it to simplify code.
>
> No functional change.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
> ---
> drivers/infiniband/core/cm.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
> index 0ead0d223154011..510beb25f5b8a0b 100644
> --- a/drivers/infiniband/core/cm.c
> +++ b/drivers/infiniband/core/cm.c
> @@ -668,8 +668,6 @@ static struct cm_id_private *cm_insert_listen(struct cm_id_private *cm_id_priv,
> link = &(*link)->rb_right;
> else if (be64_lt(service_id, cur_cm_id_priv->id.service_id))
> link = &(*link)->rb_left;
> - else if (be64_gt(service_id, cur_cm_id_priv->id.service_id))
> - link = &(*link)->rb_right;
> else
> link = &(*link)->rb_right;
> }
> @@ -700,8 +698,6 @@ static struct cm_id_private *cm_find_listen(struct ib_device *device,
> node = node->rb_right;
> else if (be64_lt(service_id, cm_id_priv->id.service_id))
> node = node->rb_left;
> - else if (be64_gt(service_id, cm_id_priv->id.service_id))
> - node = node->rb_right;
> else
> node = node->rb_right;
> }
I don't like this, if you want to reorganize this function then it
should be written in the normal pattern for this kind of comparision
if (a < b)
..
else if (a > b)
..
else // a == b
..
You can see the a==b clause written explicitly above this if ladder:
if ((cur_cm_id_priv->id.service_mask & service_id) ==
(service_mask & cur_cm_id_priv->id.service_id) &&
(cm_id_priv->id.device == cur_cm_id_priv->id.device)) {
Which is why the trailing else is just unexectuable code.
Jason
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/1] RDMA/cm: Delete two redundant condition branches
2021-05-11 19:56 ` Jason Gunthorpe
@ 2021-05-12 1:35 ` Leizhen (ThunderTown)
2021-05-12 2:17 ` Leizhen (ThunderTown)
0 siblings, 1 reply; 5+ messages in thread
From: Leizhen (ThunderTown) @ 2021-05-12 1:35 UTC (permalink / raw)
To: Jason Gunthorpe; +Cc: Doug Ledford, linux-rdma
On 2021/5/12 3:56, Jason Gunthorpe wrote:
> On Mon, May 10, 2021 at 05:08:40PM +0800, Zhen Lei wrote:
>> The statement of the last "if (xxx)" branch is the same as the "else"
>> branch. Delete it to simplify code.
>>
>> No functional change.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>> drivers/infiniband/core/cm.c | 4 ----
>> 1 file changed, 4 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
>> index 0ead0d223154011..510beb25f5b8a0b 100644
>> --- a/drivers/infiniband/core/cm.c
>> +++ b/drivers/infiniband/core/cm.c
>> @@ -668,8 +668,6 @@ static struct cm_id_private *cm_insert_listen(struct cm_id_private *cm_id_priv,
>> link = &(*link)->rb_right;
>> else if (be64_lt(service_id, cur_cm_id_priv->id.service_id))
>> link = &(*link)->rb_left;
>> - else if (be64_gt(service_id, cur_cm_id_priv->id.service_id))
>> - link = &(*link)->rb_right;
>> else
>> link = &(*link)->rb_right;
>> }
>> @@ -700,8 +698,6 @@ static struct cm_id_private *cm_find_listen(struct ib_device *device,
>> node = node->rb_right;
>> else if (be64_lt(service_id, cm_id_priv->id.service_id))
>> node = node->rb_left;
>> - else if (be64_gt(service_id, cm_id_priv->id.service_id))
>> - node = node->rb_right;
>> else
>> node = node->rb_right;
>> }
>
> I don't like this, if you want to reorganize this function then it
> should be written in the normal pattern for this kind of comparision
>
> if (a < b)
> ..
> else if (a > b)
> ..
> else // a == b
> ..
>
> You can see the a==b clause written explicitly above this if ladder:
>
> if ((cur_cm_id_priv->id.service_mask & service_id) ==
> (service_mask & cur_cm_id_priv->id.service_id) &&
> (cm_id_priv->id.device == cur_cm_id_priv->id.device)) {
Right，So we'd better rewrite it with this set of judgments. This is because
the judgment of (a < b) and (a > b) is performed N times before the judgment
of (a == b) is performed. Therefore, the above modification you mentioned can
improve the search performance.
>
> Which is why the trailing else is just unexectuable code.
>
> Jason
>
> .
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 1/1] RDMA/cm: Delete two redundant condition branches
2021-05-12 1:35 ` Leizhen (ThunderTown)
@ 2021-05-12 2:17 ` Leizhen (ThunderTown)
0 siblings, 0 replies; 5+ messages in thread
From: Leizhen (ThunderTown) @ 2021-05-12 2:17 UTC (permalink / raw)
To: Jason Gunthorpe; +Cc: Doug Ledford, linux-rdma
On 2021/5/12 9:35, Leizhen (ThunderTown) wrote:
>
>
> On 2021/5/12 3:56, Jason Gunthorpe wrote:
>> On Mon, May 10, 2021 at 05:08:40PM +0800, Zhen Lei wrote:
>>> The statement of the last "if (xxx)" branch is the same as the "else"
>>> branch. Delete it to simplify code.
>>>
>>> No functional change.
>>>
>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>>> ---
>>> drivers/infiniband/core/cm.c | 4 ----
>>> 1 file changed, 4 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
>>> index 0ead0d223154011..510beb25f5b8a0b 100644
>>> --- a/drivers/infiniband/core/cm.c
>>> +++ b/drivers/infiniband/core/cm.c
>>> @@ -668,8 +668,6 @@ static struct cm_id_private *cm_insert_listen(struct cm_id_private *cm_id_priv,
>>> link = &(*link)->rb_right;
>>> else if (be64_lt(service_id, cur_cm_id_priv->id.service_id))
>>> link = &(*link)->rb_left;
>>> - else if (be64_gt(service_id, cur_cm_id_priv->id.service_id))
>>> - link = &(*link)->rb_right;
>>> else
>>> link = &(*link)->rb_right;
>>> }
>>> @@ -700,8 +698,6 @@ static struct cm_id_private *cm_find_listen(struct ib_device *device,
>>> node = node->rb_right;
>>> else if (be64_lt(service_id, cm_id_priv->id.service_id))
>>> node = node->rb_left;
>>> - else if (be64_gt(service_id, cm_id_priv->id.service_id))
>>> - node = node->rb_right;
>>> else
>>> node = node->rb_right;
>>> }
>>
>> I don't like this, if you want to reorganize this function then it
>> should be written in the normal pattern for this kind of comparision
>>
>> if (a < b)
>> ..
>> else if (a > b)
>> ..
>> else // a == b
>> ..
>>
>> You can see the a==b clause written explicitly above this if ladder:
>>
>> if ((cur_cm_id_priv->id.service_mask & service_id) ==
>> (service_mask & cur_cm_id_priv->id.service_id) &&
>> (cm_id_priv->id.device == cur_cm_id_priv->id.device)) {
>
> Right，So we'd better rewrite it with this set of judgments. This is because
> the judgment of (a < b) and (a > b) is performed N times before the judgment
> of (a == b) is performed. Therefore, the above modification you mentioned can
> improve the search performance.
This modification may have to be patched separately. Combined with one patch, the description is unclear.
>
>>
>> Which is why the trailing else is just unexectuable code.
>>
>> Jason
>>
>> .
>>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-05-12 2:17 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-05-10 9:08 [PATCH 1/1] RDMA/cm: Delete two redundant condition branches Zhen Lei
2021-05-10 9:50 ` Leon Romanovsky
2021-05-11 19:56 ` Jason Gunthorpe
2021-05-12 1:35 ` Leizhen (ThunderTown)
2021-05-12 2:17 ` Leizhen (ThunderTown)
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