linux-kernel - [PATCH AUTOSEL 6.3 12/18] iommu/arm-smmu: Drop if with an always false condition

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Date:   Tue,  9 May 2023 17:19:20 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <jroedel@...e.de>,
        Sasha Levin <sashal@...nel.org>, will@...nel.org,
        joro@...tes.org, baolu.lu@...ux.intel.com, jgg@...pe.ca,
        robh@...nel.org, jon@...id-run.com, vladimir.oltean@....com,
        linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev
Subject: [PATCH AUTOSEL 6.3 12/18] iommu/arm-smmu: Drop if with an always false condition

From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>

[ Upstream commit a2972cb89935160bfe515b15d28a77694723ac06 ]

The remove and shutdown callback are only called after probe completed
successfully. In this case platform_set_drvdata() was called with a
non-NULL argument and so smmu is never NULL. Other functions in this
driver also don't check for smmu being non-NULL before using it.

Also note that returning an error code from a remove callback doesn't
result in the device staying bound. It's still removed and devm allocated
resources are freed (among others *smmu and the register mapping). So
after an early exit to iommu device stayed around and using it probably
oopses.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Reviewed-by: Robin Murphy <robin.murphy@....com>
Link: https://lore.kernel.org/r/20230321084125.337021-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/arm/arm-smmu/arm-smmu.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 2ff7a72cf3772..f4a36533ae478 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -2195,9 +2195,6 @@ static void arm_smmu_device_shutdown(struct platform_device *pdev)
 {
 	struct arm_smmu_device *smmu = platform_get_drvdata(pdev);
 
-	if (!smmu)
-		return;
-
 	if (!bitmap_empty(smmu->context_map, ARM_SMMU_MAX_CBS))
 		dev_notice(&pdev->dev, "disabling translation\n");
 
@@ -2218,9 +2215,6 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
 {
 	struct arm_smmu_device *smmu = platform_get_drvdata(pdev);
 
-	if (!smmu)
-		return -ENODEV;
-
 	iommu_device_unregister(&smmu->iommu);
 	iommu_device_sysfs_remove(&smmu->iommu);
 
-- 
2.39.2