From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, Will Deacon <will@kernel.org>
Cc: Qian Cai <cai@lca.pw>, Joerg Roedel <jroedel@suse.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Matthew Rosato <mjrosato@linux.ibm.com>,
Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH 1/4] vfio: Simplify vfio_create_group()
Date: Thu, 8 Sep 2022 15:44:58 -0300 [thread overview]
Message-ID: <1-v1-ef00ffecea52+2cb-iommu_group_lifetime_jgg@nvidia.com> (raw)
In-Reply-To: <0-v1-ef00ffecea52+2cb-iommu_group_lifetime_jgg@nvidia.com>
The vfio.group_lock is now only used to serialize vfio_group creation
and destruction, we don't need a micro-optimization of searching,
unlocking, then allocating and searching again. Just hold the lock
the whole time.
Rename the function to 'vfio_get_group()' to reflect that it doesn't
always create something.
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/vfio/vfio_main.c | 48 ++++++++++++++++------------------------
1 file changed, 19 insertions(+), 29 deletions(-)
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 77264d836d5200..4ab13808b536e1 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -319,17 +319,6 @@ __vfio_group_get_from_iommu(struct iommu_group *iommu_group)
return NULL;
}
-static struct vfio_group *
-vfio_group_get_from_iommu(struct iommu_group *iommu_group)
-{
- struct vfio_group *group;
-
- mutex_lock(&vfio.group_lock);
- group = __vfio_group_get_from_iommu(iommu_group);
- mutex_unlock(&vfio.group_lock);
- return group;
-}
-
static void vfio_group_release(struct device *dev)
{
struct vfio_group *group = container_of(dev, struct vfio_group, dev);
@@ -376,16 +365,26 @@ static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group,
return group;
}
-static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
- enum vfio_group_type type)
+/*
+ * Return a struct vfio_group * for the given iommu_group. If no vfio_group
+ * already exists then create a new one.
+ */
+static struct vfio_group *vfio_get_group(struct iommu_group *iommu_group,
+ enum vfio_group_type type)
{
struct vfio_group *group;
struct vfio_group *ret;
int err;
- group = vfio_group_alloc(iommu_group, type);
- if (IS_ERR(group))
- return group;
+ mutex_lock(&vfio.group_lock);
+
+ ret = __vfio_group_get_from_iommu(iommu_group);
+ if (ret)
+ goto err_unlock;
+
+ group = ret = vfio_group_alloc(iommu_group, type);
+ if (IS_ERR(ret))
+ goto err_unlock;
err = dev_set_name(&group->dev, "%s%d",
group->type == VFIO_NO_IOMMU ? "noiommu-" : "",
@@ -395,13 +394,6 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
goto err_put;
}
- mutex_lock(&vfio.group_lock);
-
- /* Did we race creating this group? */
- ret = __vfio_group_get_from_iommu(iommu_group);
- if (ret)
- goto err_unlock;
-
err = cdev_device_add(&group->cdev, &group->dev);
if (err) {
ret = ERR_PTR(err);
@@ -413,10 +405,10 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
mutex_unlock(&vfio.group_lock);
return group;
-err_unlock:
- mutex_unlock(&vfio.group_lock);
err_put:
put_device(&group->dev);
+err_unlock:
+ mutex_unlock(&vfio.group_lock);
return ret;
}
@@ -514,7 +506,7 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
if (ret)
goto out_put_group;
- group = vfio_create_group(iommu_group, type);
+ group = vfio_get_group(iommu_group, type);
if (IS_ERR(group)) {
ret = PTR_ERR(group);
goto out_remove_device;
@@ -564,9 +556,7 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
return ERR_PTR(-EINVAL);
}
- group = vfio_group_get_from_iommu(iommu_group);
- if (!group)
- group = vfio_create_group(iommu_group, VFIO_IOMMU);
+ group = vfio_get_group(iommu_group, VFIO_IOMMU);
/* The vfio_group holds a reference to the iommu_group */
iommu_group_put(iommu_group);
--
2.37.3
next prev parent reply other threads:[~2022-09-08 18:45 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-08 18:44 [PATCH 0/4] Fix splats releated to using the iommu_group after destroying devices Jason Gunthorpe
2022-09-08 18:44 ` Jason Gunthorpe [this message]
2022-09-20 19:45 ` [PATCH 1/4] vfio: Simplify vfio_create_group() Matthew Rosato
2022-09-08 18:44 ` [PATCH 2/4] vfio: Move the sanity check of the group to vfio_create_group() Jason Gunthorpe
2022-09-22 19:10 ` Alex Williamson
2022-09-22 19:36 ` Jason Gunthorpe
2022-09-22 21:23 ` Alex Williamson
2022-09-22 23:12 ` Jason Gunthorpe
2022-09-08 18:45 ` [PATCH 3/4] vfio: Follow a strict lifetime for struct iommu_group * Jason Gunthorpe
2022-09-20 19:32 ` Matthew Rosato
2022-09-08 18:45 ` [PATCH 4/4] iommu: Fix ordering of iommu_release_device() Jason Gunthorpe
2022-09-08 21:05 ` Robin Murphy
2022-09-08 21:27 ` Robin Murphy
2022-09-08 21:43 ` Jason Gunthorpe
2022-09-09 9:05 ` Robin Murphy
2022-09-09 13:25 ` Jason Gunthorpe
2022-09-09 17:57 ` Robin Murphy
2022-09-09 18:30 ` Jason Gunthorpe
2022-09-09 19:55 ` Robin Murphy
2022-09-09 23:45 ` Jason Gunthorpe
2022-09-12 11:13 ` Robin Murphy
2022-09-22 16:56 ` Jason Gunthorpe
2022-09-09 12:49 ` [PATCH 0/4] Fix splats releated to using the iommu_group after destroying devices Matthew Rosato
2022-09-09 16:24 ` Jason Gunthorpe
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