From: John Garry <john.garry@huawei.com>
Date: Tue, 22 Jun 2021 00:36:34 +0800
Subject: iommu/arm-smmu-v3: Remove some unneeded init in
arm_smmu_cmdq_issue_cmdlist()
Git-commit: 5c08c5acdc6ce46296a0f98d06896c818b8b34e0
Patch-mainline: v5.15-rc1
References: bsc#1192202
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>
Link: https://lore.kernel.org/r/1624293394-202509-1-git-send-email-john.garry@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- 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(s
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);