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From: Zhen Lei <thunder.leizhen@huawei.com>
To: Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	"Joerg Roedel" <joro@8bytes.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	iommu <iommu@lists.linux-foundation.org>,
	<linux-kernel@vger.kernel.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>,
	John Garry <john.garry@huawei.com>
Subject: [PATCH v2 1/2] iommu/arm-smmu-v3: Properly handle the return value of arm_smmu_cmdq_build_cmd()
Date: Wed, 18 Aug 2021 16:04:51 +0800	[thread overview]
Message-ID: <20210818080452.2079-2-thunder.leizhen@huawei.com> (raw)
In-Reply-To: <20210818080452.2079-1-thunder.leizhen@huawei.com>

1. Build command CMD_SYNC cannot fail. So the return value can be ignored.
2. The arm_smmu_cmdq_build_cmd() almost never fails, the addition of
   "unlikely()" can optimize the instruction pipeline.
3. Check the return value in arm_smmu_cmdq_batch_add().

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

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 3646bf8f021cd4c..01e95b56ffa07d1 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -409,10 +409,7 @@ static void __arm_smmu_cmdq_skip_err(struct arm_smmu_device *smmu,
 		dev_err(smmu->dev, "\t0x%016llx\n", (unsigned long long)cmd[i]);
 
 	/* Convert the erroneous command into a CMD_SYNC */
-	if (arm_smmu_cmdq_build_cmd(cmd, &cmd_sync)) {
-		dev_err(smmu->dev, "failed to convert to CMD_SYNC\n");
-		return;
-	}
+	arm_smmu_cmdq_build_cmd(cmd, &cmd_sync);
 
 	queue_write(Q_ENT(q, cons), cmd, q->ent_dwords);
 }
@@ -860,7 +857,7 @@ static int __arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
 {
 	u64 cmd[CMDQ_ENT_DWORDS];
 
-	if (arm_smmu_cmdq_build_cmd(cmd, ent)) {
+	if (unlikely(arm_smmu_cmdq_build_cmd(cmd, ent))) {
 		dev_warn(smmu->dev, "ignoring unknown CMDQ opcode 0x%x\n",
 			 ent->opcode);
 		return -EINVAL;
@@ -885,11 +882,20 @@ static void arm_smmu_cmdq_batch_add(struct arm_smmu_device *smmu,
 				    struct arm_smmu_cmdq_batch *cmds,
 				    struct arm_smmu_cmdq_ent *cmd)
 {
+	int index;
+
 	if (cmds->num == CMDQ_BATCH_ENTRIES) {
 		arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, false);
 		cmds->num = 0;
 	}
-	arm_smmu_cmdq_build_cmd(&cmds->cmds[cmds->num * CMDQ_ENT_DWORDS], cmd);
+
+	index = cmds->num * CMDQ_ENT_DWORDS;
+	if (unlikely(arm_smmu_cmdq_build_cmd(&cmds->cmds[index], cmd))) {
+		dev_warn(smmu->dev, "ignoring unknown CMDQ opcode 0x%x\n",
+			 cmd->opcode);
+		return;
+	}
+
 	cmds->num++;
 }
 
-- 
2.26.0.106.g9fadedd


  reply	other threads:[~2021-08-18  8:05 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18  8:04 [PATCH v2 0/2] iommu/arm-smmu-v3: Perform some simple optimizations for arm_smmu_cmdq_build_cmd() Zhen Lei
2021-08-18  8:04 ` Zhen Lei [this message]
2021-08-18  8:04 ` [PATCH v2 2/2] iommu/arm-smmu-v3: Simplify useless instructions in arm_smmu_cmdq_build_cmd() Zhen Lei
2021-10-04 12:07   ` Will Deacon
2021-10-20  7:29     ` Leizhen (ThunderTown)
2021-10-04 12:05 ` [PATCH v2 0/2] iommu/arm-smmu-v3: Perform some simple optimizations for arm_smmu_cmdq_build_cmd() Will Deacon

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