linux-kernel - [PATCH v2] vfio/type1: avoid redundant PageReserved checking

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Date:   Wed, 28 Aug 2019 12:28:04 +0800
From:   Ben Luo <luoben@...ux.alibaba.com>
To:     alex.williamson@...hat.com, cohuck@...hat.com
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v2] vfio/type1: avoid redundant PageReserved checking

currently, if the page is not a tail of compound page, it will be
checked twice for the same thing.

Signed-off-by: Ben Luo <luoben@...ux.alibaba.com>
---
 drivers/vfio/vfio_iommu_type1.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 054391f..d0f7346 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -291,11 +291,10 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
 static bool is_invalid_reserved_pfn(unsigned long pfn)
 {
 	if (pfn_valid(pfn)) {
-		bool reserved;
 		struct page *tail = pfn_to_page(pfn);
 		struct page *head = compound_head(tail);
-		reserved = !!(PageReserved(head));
 		if (head != tail) {
+			bool reserved = PageReserved(head);
 			/*
 			 * "head" is not a dangling pointer
 			 * (compound_head takes care of that)
-- 
1.8.3.1