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Mon, 30 Mar 2020 17:24:18 +0000 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 30 Mar 2020 10:24:25 -0700 From: Kirti Wankhede To: , Subject: [PATCH v17 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Mon, 30 Mar 2020 22:20:39 +0530 Message-ID: <1585587044-2408-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1585587044-2408-1-git-send-email-kwankhede@nvidia.com> References: <1585587044-2408-1-git-send-email-kwankhede@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1585588970; bh=gmeXbRuItwuzRSa4wja8NeNbAoIY5SLtg52zFZ81snk=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:X-NVConfidentiality:MIME-Version: Content-Type; b=PdT3FdBDDzumHBMmfU1POMHCTDTmnm5Vv+fllHthZV4cJl5z7oouqOHw2kEFMIyuQ MUsWM2KPA6gmbK2NNcyc5EkxgqybYIEoJSQJ77Sxbo36+OgBmb+y5+LmxWfyuEe4R4 Cz7pqAaglF43rFbJ+STzkAQEjFqa+UU2EN7Ut3fIjQkzz740OifDRyC10YKNPSzhlF xpJPeY481uPF+5esHphuPCqo11zidwjsAtIcFtbGe62uZdVn2PQ8JIuPNpfiyHw2RS 8ozBbgiZhkANXsINsA8dKDa9CDAZr6hJRhpuuPNg6ubFzTz1OjxjbLPkvjihL9IDj0 i9lo0RT1/HWmw== X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy] X-Received-From: 216.228.121.143 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com, yan.y.zhao@intel.com, kvm@vger.kernel.org, eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, Kirti Wankhede , eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" vfio_pfn.ref_count is always updated while holding iommu->lock, using atomic variable is overkill. Signed-off-by: Kirti Wankhede Reviewed-by: Neo Jia Reviewed-by: Eric Auger Reviewed-by: Cornelia Huck --- drivers/vfio/vfio_iommu_type1.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type= 1.c index 9fdfae1cb17a..70aeab921d0f 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -112,7 +112,7 @@ struct vfio_pfn { struct rb_node node; dma_addr_t iova; /* Device address */ unsigned long pfn; /* Host pfn */ - atomic_t ref_count; + unsigned int ref_count; }; =20 struct vfio_regions { @@ -233,7 +233,7 @@ static int vfio_add_to_pfn_list(struct vfio_dma *dma, d= ma_addr_t iova, =20 vpfn->iova =3D iova; vpfn->pfn =3D pfn; - atomic_set(&vpfn->ref_count, 1); + vpfn->ref_count =3D 1; vfio_link_pfn(dma, vpfn); return 0; } @@ -251,7 +251,7 @@ static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct v= fio_dma *dma, struct vfio_pfn *vpfn =3D vfio_find_vpfn(dma, iova); =20 if (vpfn) - atomic_inc(&vpfn->ref_count); + vpfn->ref_count++; return vpfn; } =20 @@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma,= struct vfio_pfn *vpfn) { int ret =3D 0; =20 - if (atomic_dec_and_test(&vpfn->ref_count)) { + vpfn->ref_count--; + if (!vpfn->ref_count) { ret =3D put_pfn(vpfn->pfn, dma->prot); vfio_remove_from_pfn_list(dma, vpfn); } --=20 2.7.0