linux-kernel - [PATCH v3 1/3] iova: Remove some magazine pointer NULL checks

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Date:   Wed, 7 Sep 2022 21:02:32 +0800
From:   John Garry <john.garry@...wei.com>
To:     <robin.murphy@....com>, <joro@...tes.org>, <will@...nel.org>
CC:     <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <jsnitsel@...hat.com>,
        <haifeng.zhao@...ux.intel.com>, John Garry <john.garry@...wei.com>
Subject: [PATCH v3 1/3] iova: Remove some magazine pointer NULL checks

Since commit 32e92d9f6f87 ("iommu/iova: Separate out rcache init") it
has not been possible to have NULL CPU rcache "loaded" or "prev" magazine
pointers once the IOVA domain has been properly initialized. Previously it
was only possible to have NULL pointers from failure to allocate the
magazines in the IOVA domain initialization. The only other two functions
to modify these pointers - __iova_rcache_{get, insert}() - would already
ensure that these pointers were non-NULL if initially non-NULL.

As such, the mag NULL pointer checks in iova_magazine_full(),
iova_magazine_empty(), and iova_magazine_free_pfns() may be dropped.

Signed-off-by: John Garry <john.garry@...wei.com>
Reviewed-by: Robin Murphy <robin.murphy@....com>
Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>
---
 drivers/iommu/iova.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 47d1983dfa2a..580fdf669922 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -661,9 +661,6 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 	unsigned long flags;
 	int i;
 
-	if (!mag)
-		return;
-
 	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
 
 	for (i = 0 ; i < mag->size; ++i) {
@@ -683,12 +680,12 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
 
 static bool iova_magazine_full(struct iova_magazine *mag)
 {
-	return (mag && mag->size == IOVA_MAG_SIZE);
+	return mag->size == IOVA_MAG_SIZE;
 }
 
 static bool iova_magazine_empty(struct iova_magazine *mag)
 {
-	return (!mag || mag->size == 0);
+	return mag->size == 0;
 }
 
 static unsigned long iova_magazine_pop(struct iova_magazine *mag,
-- 
2.25.1