* [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master()
@ 2021-08-17 11:34 Zhen Lei
2021-08-17 11:53 ` John Garry
2021-10-04 12:05 ` Will Deacon
0 siblings, 2 replies; 3+ messages in thread
From: Zhen Lei @ 2021-08-17 11:34 UTC (permalink / raw)
To: Will Deacon, Robin Murphy, Joerg Roedel, linux-arm-kernel, iommu,
linux-kernel
Pre-zeroing the batched commands structure is inefficient, as individual
commands are zeroed later in arm_smmu_cmdq_build_cmd(). Therefore, only
the member 'num' needs to be initialized to 0.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 50a9db5bac466c7..e6882ae81fd08f6 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1776,10 +1776,11 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
{
int i;
struct arm_smmu_cmdq_ent cmd;
- struct arm_smmu_cmdq_batch cmds = {};
+ struct arm_smmu_cmdq_batch cmds;
arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
+ cmds.num = 0;
for (i = 0; i < master->num_streams; i++) {
cmd.atc.sid = master->streams[i].id;
arm_smmu_cmdq_batch_add(master->smmu, &cmds, &cmd);
--
2.26.0.106.g9fadedd
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^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master()
2021-08-17 11:34 [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master() Zhen Lei
@ 2021-08-17 11:53 ` John Garry
2021-10-04 12:05 ` Will Deacon
1 sibling, 0 replies; 3+ messages in thread
From: John Garry @ 2021-08-17 11:53 UTC (permalink / raw)
To: Zhen Lei, Will Deacon, Robin Murphy, Joerg Roedel,
linux-arm-kernel, iommu, linux-kernel
On 17/08/2021 12:34, Zhen Lei wrote:
> Pre-zeroing the batched commands structure is inefficient, as individual
> commands are zeroed later in arm_smmu_cmdq_build_cmd(). Therefore, only
> the member 'num' needs to be initialized to 0.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
> ---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 50a9db5bac466c7..e6882ae81fd08f6 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -1776,10 +1776,11 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
> {
> int i;
> struct arm_smmu_cmdq_ent cmd;
> - struct arm_smmu_cmdq_batch cmds = {};
> + struct arm_smmu_cmdq_batch cmds;
>
> arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd);
>
> + cmds.num = 0;
We prob should have added a comment why we do this (and at the other
sites). I think Robin said something similar in another patch.
> for (i = 0; i < master->num_streams; i++) {
> cmd.atc.sid = master->streams[i].id;
> arm_smmu_cmdq_batch_add(master->smmu, &cmds, &cmd);
>
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master()
2021-08-17 11:34 [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master() Zhen Lei
2021-08-17 11:53 ` John Garry
@ 2021-10-04 12:05 ` Will Deacon
1 sibling, 0 replies; 3+ messages in thread
From: Will Deacon @ 2021-10-04 12:05 UTC (permalink / raw)
To: linux-kernel, Robin Murphy, Joerg Roedel, linux-arm-kernel,
Zhen Lei, iommu
Cc: catalin.marinas, kernel-team, Will Deacon
On Tue, 17 Aug 2021 19:34:11 +0800, Zhen Lei wrote:
> Pre-zeroing the batched commands structure is inefficient, as individual
> commands are zeroed later in arm_smmu_cmdq_build_cmd(). Therefore, only
> the member 'num' needs to be initialized to 0.
>
>
Applied to will (for-joerg/arm-smmu/updates), thanks!
[1/1] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master()
https://git.kernel.org/will/c/93f9f7958f12
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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2021-08-17 11:34 [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master() Zhen Lei
2021-08-17 11:53 ` John Garry
2021-10-04 12:05 ` Will Deacon
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