Messages in this thread Patch in this message | | | From | John Garry <> | Subject | [PATCH] iommu/arm-smmu-v3: Remove some unneeded init in arm_smmu_cmdq_issue_cmdlist() | Date | Tue, 22 Jun 2021 00:36:34 +0800 |
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Members of struct "llq" will be zero-inited, apart from member max_n_shift. But we write llq.val straight after the init, so it was pointless to zero init those other members. As such, separately init member max_n_shift only.
In addition, struct "head" is initialised to "llq" only so that member max_n_shift is set. But that member is never referenced for "head", so remove any init there.
Removing these initializations is seen as a small performance optimisation, as this code is (very) hot path.
Signed-off-by: John Garry <john.garry@huawei.com>
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 54b2f27b81d4..8a8ad49bb7fd 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -727,11 +727,11 @@ static int arm_smmu_cmdq_issue_cmdlist(struct arm_smmu_device *smmu, unsigned long flags; bool owner; struct arm_smmu_cmdq *cmdq = &smmu->cmdq; - struct arm_smmu_ll_queue llq = { - .max_n_shift = cmdq->q.llq.max_n_shift, - }, head = llq; + struct arm_smmu_ll_queue llq, head; int ret = 0; + llq.max_n_shift = cmdq->q.llq.max_n_shift; + /* 1. Allocate some space in the queue */ local_irq_save(flags); llq.val = READ_ONCE(cmdq->q.llq.val); -- 2.26.2
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