drm/i915/gem: Drop local vma->vm_file reference (f17b8980) · Commits · 戴 / test

drivers/gpu/drm/i915/gem/i915_gem_mman.c

+59 −0

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@
		* Copyright © 2014-2016 Intel Corporation
		*/

		#include <linux/anon_inodes.h>
		#include <linux/mman.h>
		#include <linux/pfn_t.h>
		#include <linux/sizes.h>
		@@ -686,6 +687,46 @@ static const struct vm_operations_struct vm_ops_cpu = {
		.close = vm_close,
		};

		static int singleton_release(struct inode inode, struct file file)
		{
		struct drm_i915_private *i915 = file->private_data;

		cmpxchg(&i915->gem.mmap_singleton, file, NULL);
		drm_dev_put(&i915->drm);

		return 0;
		}

		static const struct file_operations singleton_fops = {
		.owner = THIS_MODULE,
		.release = singleton_release,
		};

		static struct file mmap_singleton(struct drm_i915_private i915)
		{
		struct file *file;

		rcu_read_lock();
		file = i915->gem.mmap_singleton;
		if (file && !get_file_rcu(file))
		file = NULL;
		rcu_read_unlock();
		if (file)
		return file;

		file = anon_inode_getfile("i915.gem", &singleton_fops, i915, O_RDWR);
		if (IS_ERR(file))
		return file;

		/* Everyone shares a single global address space */
		file->f_mapping = i915->drm.anon_inode->i_mapping;

		smp_store_mb(i915->gem.mmap_singleton, file);
		drm_dev_get(&i915->drm);

		return file;
		}

		/*
		* This overcomes the limitation in drm_gem_mmap's assignment of a
		* drm_gem_object as the vma->vm_private_data. Since we need to
		@@ -699,6 +740,7 @@ int i915_gem_mmap(struct file filp, struct vm_area_struct vma)
		struct drm_device *dev = priv->minor->dev;
		struct i915_mmap_offset *mmo = NULL;
		struct drm_gem_object *obj = NULL;
		struct file *anon;

		if (drm_dev_is_unplugged(dev))
		return -ENODEV;
		@@ -747,9 +789,26 @@ int i915_gem_mmap(struct file filp, struct vm_area_struct vma)
		vma->vm_flags &= ~VM_MAYWRITE;
		}

		anon = mmap_singleton(to_i915(obj->dev));
		if (IS_ERR(anon)) {
		drm_gem_object_put_unlocked(obj);
		return PTR_ERR(anon);
		}

		vma->vm_flags \|= VM_PFNMAP \| VM_DONTEXPAND \| VM_DONTDUMP;
		vma->vm_private_data = mmo;

		/*
		* We keep the ref on mmo->obj, not vm_file, but we require
		* vma->vm_file->f_mapping, see vma_link(), for later revocation.
		* Our userspace is accustomed to having per-file resource cleanup
		* (i.e. contexts, objects and requests) on their close(fd), which
		* requires avoiding extraneous references to their filp, hence why
		* we prefer to use an anonymous file for their mmaps.
		*/
		fput(vma->vm_file);
		vma->vm_file = anon;

		switch (mmo->mmap_type) {
		case I915_MMAP_TYPE_WC:
		vma->vm_page_prot =

drivers/gpu/drm/i915/i915_drv.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -1252,6 +1252,16 @@ struct drm_i915_private {
		struct llist_head free_list;
		struct work_struct free_work;
		} contexts;

		/*
		* We replace the local file with a global mappings as the
		* backing storage for the mmap is on the device and not
		* on the struct file, and we do not want to prolong the
		* lifetime of the local fd. To minimise the number of
		* anonymous inodes we create, we use a global singleton to
		* share the global mapping.
		*/
		struct file *mmap_singleton;
		} gem;

		u8 pch_ssc_use;

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