From: John Garry Date: Mon, 21 Jun 2021 16:36:34 +0000 (+0800) Subject: iommu/arm-smmu-v3: Remove some unneeded init in arm_smmu_cmdq_issue_cmdlist() X-Git-Tag: Ubuntu-5.15.0-12.12~1905^2^3~1^2~9 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=5c08c5acdc6ce46296a0f98d06896c818b8b34e0;p=mirror_ubuntu-jammy-kernel.git iommu/arm-smmu-v3: Remove some unneeded init in arm_smmu_cmdq_issue_cmdlist() 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 Link: https://lore.kernel.org/r/1624293394-202509-1-git-send-email-john.garry@huawei.com Signed-off-by: Will Deacon --- 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 235f9bdaeaf2..952291840c76 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -733,11 +733,11 @@ 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);