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authorYuqi Jin <jinyuqi@huawei.com>2020-08-27 11:43:54 +0300
committerJoerg Roedel <jroedel@suse.de>2020-09-04 13:11:06 +0300
commitba328f82613260a098de7b4aff58743cd8733507 (patch)
treee5640a2d5d96de57d1d679e81804ac45f1fec9c7 /drivers/iommu/iova.c
parent4604393ca0c6e4a73c04798c3f1d9878e70b7251 (diff)
downloadlinux-ba328f82613260a098de7b4aff58743cd8733507.tar.xz
iommu/iova: Replace cmpxchg with xchg in queue_iova
The performance of the atomic_xchg is better than atomic_cmpxchg because no comparison is required. While the value of @fq_timer_on can only be 0 or 1. Let's use atomic_xchg instead of atomic_cmpxchg here because we only need to check that the value changes from 0 to 1 or from 1 to 1. Signed-off-by: Yuqi Jin <jinyuqi@huawei.com> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Cc: Joerg Roedel <joro@8bytes.org> Link: https://lore.kernel.org/r/1598517834-30275-1-git-send-email-zhangshaokun@hisilicon.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu/iova.c')
-rw-r--r--drivers/iommu/iova.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 45a251da5453..30d969a4c5fd 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -579,7 +579,7 @@ void queue_iova(struct iova_domain *iovad,
/* Avoid false sharing as much as possible. */
if (!atomic_read(&iovad->fq_timer_on) &&
- !atomic_cmpxchg(&iovad->fq_timer_on, 0, 1))
+ !atomic_xchg(&iovad->fq_timer_on, 1))
mod_timer(&iovad->fq_timer,
jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
}